Case Reports

Paraneoplastic syndrome is a rare disorder involving manifestations of immune dysregulation triggered by malignancy. The immune system develops antibodies to the malignancy, which can cause cross reactivation with various tissues in the body, resulting in an autoimmune response. Paraneoplastic cerebellar degeneration (PCD) is a rare condition caused by immune-mediated damage to the Purkinje cells of the cerebellar tract. Symptoms may include gait instability, double vision, decreased fine motor skills, and ataxia, with progression to brainstem-associated symptoms, such as nystagmus, dysarthria, and dysphagia. Early detection and treatment of the underlying malignancy is critical to halt the progression of autoimmune-mediated destruction. We present a case of a young adult female patient with PCD caused by Purkinje cell cytoplasmic–Tr (PCA-Tr) antibody with Hodgkin lymphoma.

Case Presentation

A 20-year-old previously healthy active-duty female patient presented to the emergency department with acute worsening of chronic intermittent, recurrent episodes of lightheadedness and vertigo. Symptoms persisted for 9 months until acutely worsening over the 2 weeks prior to presentation. She reported left eye double vision but did not report seeing spots, photophobia, tinnitus, or headache. She felt off-balance, leaning on nearby objects to remain standing. Symptoms primarily occurred during ambulation; however, occasionally they happened at rest. Episodes lasted up to several minutes and occurred up to 15 times a day. The patient reported no fever, night sweats, unexplained weight loss, muscle aches, weakness, numbness or tingling, loss of bowel or bladder function, or rash. She had no recent illnesses, changes to medications, or recent travel. Oral intake to include food and water was adequate and unchanged. The patient had a remote history of mild concussions without loss of consciousness while playing sports 4 years previously. She reported no recent trauma. Nine months before, she received treatment for benign paroxysmal positional vertigo (BPPV) with the Epley maneuver with full resolution of symptoms lasting several days. She reported no prescription or over-the-counter medications, herbal remedies, or supplements. She reported no other medical or surgical history and no pertinent social or family history.

Physical examination revealed a nontoxic-appearing female patient with intermittent conversational dysarthria, saccadic pursuits, horizontal nystagmus with lateral gaze, and vertical nystagmus with vertical gaze. The patient exhibited dysdiadochokinesia, or impaired ability to perform rapid alternating hand movements with repetition. Finger-to-nose testing was impaired and heel-to-shin motion remained intact. A Romberg test was positive, and the patient had tandem gait instability. Strength testing, sensation, reflexes, and cranial nerves were otherwise intact. Initial laboratory testing was unremarkable except for mild normocytic anemia. Her infectious workup, including testing for venereal disease, HIV, COVID-19, and Coccidioidies was negative. Heavy metals analysis and urine drug screen were negative. Ophthalmology was consulted and workup revealed small amplitude downbeat nystagmus in primary gaze, sustained gaze evoked lateral beating jerk nystagmus with rebound nystagmus R>L gaze, but there was no evidence of afferent package defect and optic nerve function remained intact. Magnetic resonance imaging of the brain demonstrated cerebellar vermis hypoplasia with prominence of the superior cerebellar folia. Due to concerns for autoimmune encephalitis, a lumbar puncture was performed. Antibody testing revealed PCA-Tr antibodies, which is commonly associated with Hodgkin lymphoma, prompting further evaluation for malignancy.

Computed tomography (CT) of the chest with contrast demonstrated multiple mediastinal masses with a conglomeration of lymph nodes along the right paratracheal region. Further evaluation was performed with a positron emission tomography (PET)–CT, revealing a large conglomeration of hypermetabolic pretracheal, mediastinal, and right supraclavicular lymph that were suggestive of lymphoma. Mediastinoscopy with excisional lymph node biopsy was performed with immunohistochemical staining confirming diagnosis of a nodular sclerosing variant of Hodgkin lymphoma. The patient was treated with IV immunoglobulin at 0.4g/kg daily for 5 days. A central venous catheter was placed into the patient’s right internal jugular vein and a chemotherapy regimen of doxorubicin 46 mg, vinblastine 11 mg, bleomycin 19 units, and dacarbazine 700 mg was initiated. The patient’s symptoms improved with resolution of dysarthria; however, her visual impairment and gait instability persisted. Repeat PET-CT imaging 2 months later revealed interval improvement with decreased intensity and extent of the hypermetabolic lymph nodes and no new hypermetabolic foci.

Discussion

PCA-Tr antibodies affect the delta/notchlike epidermal growth factor–related receptor, expressed on the dendrites of cerebellar Purkinje cells.¹ These fibers are the only output neurons of the cerebellar cortex and are critical to the coordination of motor movements, accounting for the ataxia experienced by patients with this subtype of PCD.² The link between Hodgkin lymphoma and PCA-Tr antibodies has been established; however, most reports involve men with a median age of 61 years with lymphoma-associated symptoms (such as lymphadenopathy) or systemic symptoms (fever, night sweats, or weight loss) preceding neurologic manifestations in 80% of cases.³

Our patient was a young, previously healthy adult female who initially presented with vertigo, a common concern with frequently benign origins. Although there was temporary resolution of symptoms after Epley maneuvers, symptoms recurred and progressed over several months to include brainstem manifestations of nystagmus, diplopia, and dysarthria. Previous reports indicate that after remission of the Hodgkin lymphoma, PCA-Tr antibodies disappear and symptoms can improve or resolve.^4,5 Treatment has just begun for our patient and although there has been initial clinical improvement, given the chronicity of symptoms, it is unclear if complete resolution will be achieved.

Conclusions

PCD can result in debilitating neurologic dysfunction and may be associated with malignancy such as Hodgkin lymphoma. This case offers unique insight due to the patient’s demographics and presentation, which involved brainstem pathology typically associated with late-onset disease and preceded by constitutional symptoms. Clinical suspicion of this rare disorder should be considered in all ages, especially if symptoms are progressive or neurologic manifestations arise, as early detection and treatment of the underlying malignancy are paramount to the prevention of significant disability.

Paraneoplastic syndrome is a rare disorder involving manifestations of immune dysregulation triggered by malignancy. The immune system develops antibodies to the malignancy, which can cause cross reactivation with various tissues in the body, resulting in an autoimmune response. Paraneoplastic cerebellar degeneration (PCD) is a rare condition caused by immune-mediated damage to the Purkinje cells of the cerebellar tract. Symptoms may include gait instability, double vision, decreased fine motor skills, and ataxia, with progression to brainstem-associated symptoms, such as nystagmus, dysarthria, and dysphagia. Early detection and treatment of the underlying malignancy is critical to halt the progression of autoimmune-mediated destruction. We present a case of a young adult female patient with PCD caused by Purkinje cell cytoplasmic–Tr (PCA-Tr) antibody with Hodgkin lymphoma.

Case Presentation

A 20-year-old previously healthy active-duty female patient presented to the emergency department with acute worsening of chronic intermittent, recurrent episodes of lightheadedness and vertigo. Symptoms persisted for 9 months until acutely worsening over the 2 weeks prior to presentation. She reported left eye double vision but did not report seeing spots, photophobia, tinnitus, or headache. She felt off-balance, leaning on nearby objects to remain standing. Symptoms primarily occurred during ambulation; however, occasionally they happened at rest. Episodes lasted up to several minutes and occurred up to 15 times a day. The patient reported no fever, night sweats, unexplained weight loss, muscle aches, weakness, numbness or tingling, loss of bowel or bladder function, or rash. She had no recent illnesses, changes to medications, or recent travel. Oral intake to include food and water was adequate and unchanged. The patient had a remote history of mild concussions without loss of consciousness while playing sports 4 years previously. She reported no recent trauma. Nine months before, she received treatment for benign paroxysmal positional vertigo (BPPV) with the Epley maneuver with full resolution of symptoms lasting several days. She reported no prescription or over-the-counter medications, herbal remedies, or supplements. She reported no other medical or surgical history and no pertinent social or family history.

Physical examination revealed a nontoxic-appearing female patient with intermittent conversational dysarthria, saccadic pursuits, horizontal nystagmus with lateral gaze, and vertical nystagmus with vertical gaze. The patient exhibited dysdiadochokinesia, or impaired ability to perform rapid alternating hand movements with repetition. Finger-to-nose testing was impaired and heel-to-shin motion remained intact. A Romberg test was positive, and the patient had tandem gait instability. Strength testing, sensation, reflexes, and cranial nerves were otherwise intact. Initial laboratory testing was unremarkable except for mild normocytic anemia. Her infectious workup, including testing for venereal disease, HIV, COVID-19, and Coccidioidies was negative. Heavy metals analysis and urine drug screen were negative. Ophthalmology was consulted and workup revealed small amplitude downbeat nystagmus in primary gaze, sustained gaze evoked lateral beating jerk nystagmus with rebound nystagmus R>L gaze, but there was no evidence of afferent package defect and optic nerve function remained intact. Magnetic resonance imaging of the brain demonstrated cerebellar vermis hypoplasia with prominence of the superior cerebellar folia. Due to concerns for autoimmune encephalitis, a lumbar puncture was performed. Antibody testing revealed PCA-Tr antibodies, which is commonly associated with Hodgkin lymphoma, prompting further evaluation for malignancy.

Computed tomography (CT) of the chest with contrast demonstrated multiple mediastinal masses with a conglomeration of lymph nodes along the right paratracheal region. Further evaluation was performed with a positron emission tomography (PET)–CT, revealing a large conglomeration of hypermetabolic pretracheal, mediastinal, and right supraclavicular lymph that were suggestive of lymphoma. Mediastinoscopy with excisional lymph node biopsy was performed with immunohistochemical staining confirming diagnosis of a nodular sclerosing variant of Hodgkin lymphoma. The patient was treated with IV immunoglobulin at 0.4g/kg daily for 5 days. A central venous catheter was placed into the patient’s right internal jugular vein and a chemotherapy regimen of doxorubicin 46 mg, vinblastine 11 mg, bleomycin 19 units, and dacarbazine 700 mg was initiated. The patient’s symptoms improved with resolution of dysarthria; however, her visual impairment and gait instability persisted. Repeat PET-CT imaging 2 months later revealed interval improvement with decreased intensity and extent of the hypermetabolic lymph nodes and no new hypermetabolic foci.

Discussion

PCA-Tr antibodies affect the delta/notchlike epidermal growth factor–related receptor, expressed on the dendrites of cerebellar Purkinje cells.¹ These fibers are the only output neurons of the cerebellar cortex and are critical to the coordination of motor movements, accounting for the ataxia experienced by patients with this subtype of PCD.² The link between Hodgkin lymphoma and PCA-Tr antibodies has been established; however, most reports involve men with a median age of 61 years with lymphoma-associated symptoms (such as lymphadenopathy) or systemic symptoms (fever, night sweats, or weight loss) preceding neurologic manifestations in 80% of cases.³

Our patient was a young, previously healthy adult female who initially presented with vertigo, a common concern with frequently benign origins. Although there was temporary resolution of symptoms after Epley maneuvers, symptoms recurred and progressed over several months to include brainstem manifestations of nystagmus, diplopia, and dysarthria. Previous reports indicate that after remission of the Hodgkin lymphoma, PCA-Tr antibodies disappear and symptoms can improve or resolve.^4,5 Treatment has just begun for our patient and although there has been initial clinical improvement, given the chronicity of symptoms, it is unclear if complete resolution will be achieved.

Conclusions

PCD can result in debilitating neurologic dysfunction and may be associated with malignancy such as Hodgkin lymphoma. This case offers unique insight due to the patient’s demographics and presentation, which involved brainstem pathology typically associated with late-onset disease and preceded by constitutional symptoms. Clinical suspicion of this rare disorder should be considered in all ages, especially if symptoms are progressive or neurologic manifestations arise, as early detection and treatment of the underlying malignancy are paramount to the prevention of significant disability.

Paraneoplastic syndrome is a rare disorder involving manifestations of immune dysregulation triggered by malignancy. The immune system develops antibodies to the malignancy, which can cause cross reactivation with various tissues in the body, resulting in an autoimmune response. Paraneoplastic cerebellar degeneration (PCD) is a rare condition caused by immune-mediated damage to the Purkinje cells of the cerebellar tract. Symptoms may include gait instability, double vision, decreased fine motor skills, and ataxia, with progression to brainstem-associated symptoms, such as nystagmus, dysarthria, and dysphagia. Early detection and treatment of the underlying malignancy is critical to halt the progression of autoimmune-mediated destruction. We present a case of a young adult female patient with PCD caused by Purkinje cell cytoplasmic–Tr (PCA-Tr) antibody with Hodgkin lymphoma.

Case Presentation

A 20-year-old previously healthy active-duty female patient presented to the emergency department with acute worsening of chronic intermittent, recurrent episodes of lightheadedness and vertigo. Symptoms persisted for 9 months until acutely worsening over the 2 weeks prior to presentation. She reported left eye double vision but did not report seeing spots, photophobia, tinnitus, or headache. She felt off-balance, leaning on nearby objects to remain standing. Symptoms primarily occurred during ambulation; however, occasionally they happened at rest. Episodes lasted up to several minutes and occurred up to 15 times a day. The patient reported no fever, night sweats, unexplained weight loss, muscle aches, weakness, numbness or tingling, loss of bowel or bladder function, or rash. She had no recent illnesses, changes to medications, or recent travel. Oral intake to include food and water was adequate and unchanged. The patient had a remote history of mild concussions without loss of consciousness while playing sports 4 years previously. She reported no recent trauma. Nine months before, she received treatment for benign paroxysmal positional vertigo (BPPV) with the Epley maneuver with full resolution of symptoms lasting several days. She reported no prescription or over-the-counter medications, herbal remedies, or supplements. She reported no other medical or surgical history and no pertinent social or family history.

Physical examination revealed a nontoxic-appearing female patient with intermittent conversational dysarthria, saccadic pursuits, horizontal nystagmus with lateral gaze, and vertical nystagmus with vertical gaze. The patient exhibited dysdiadochokinesia, or impaired ability to perform rapid alternating hand movements with repetition. Finger-to-nose testing was impaired and heel-to-shin motion remained intact. A Romberg test was positive, and the patient had tandem gait instability. Strength testing, sensation, reflexes, and cranial nerves were otherwise intact. Initial laboratory testing was unremarkable except for mild normocytic anemia. Her infectious workup, including testing for venereal disease, HIV, COVID-19, and Coccidioidies was negative. Heavy metals analysis and urine drug screen were negative. Ophthalmology was consulted and workup revealed small amplitude downbeat nystagmus in primary gaze, sustained gaze evoked lateral beating jerk nystagmus with rebound nystagmus R>L gaze, but there was no evidence of afferent package defect and optic nerve function remained intact. Magnetic resonance imaging of the brain demonstrated cerebellar vermis hypoplasia with prominence of the superior cerebellar folia. Due to concerns for autoimmune encephalitis, a lumbar puncture was performed. Antibody testing revealed PCA-Tr antibodies, which is commonly associated with Hodgkin lymphoma, prompting further evaluation for malignancy.

Computed tomography (CT) of the chest with contrast demonstrated multiple mediastinal masses with a conglomeration of lymph nodes along the right paratracheal region. Further evaluation was performed with a positron emission tomography (PET)–CT, revealing a large conglomeration of hypermetabolic pretracheal, mediastinal, and right supraclavicular lymph that were suggestive of lymphoma. Mediastinoscopy with excisional lymph node biopsy was performed with immunohistochemical staining confirming diagnosis of a nodular sclerosing variant of Hodgkin lymphoma. The patient was treated with IV immunoglobulin at 0.4g/kg daily for 5 days. A central venous catheter was placed into the patient’s right internal jugular vein and a chemotherapy regimen of doxorubicin 46 mg, vinblastine 11 mg, bleomycin 19 units, and dacarbazine 700 mg was initiated. The patient’s symptoms improved with resolution of dysarthria; however, her visual impairment and gait instability persisted. Repeat PET-CT imaging 2 months later revealed interval improvement with decreased intensity and extent of the hypermetabolic lymph nodes and no new hypermetabolic foci.

Discussion

PCA-Tr antibodies affect the delta/notchlike epidermal growth factor–related receptor, expressed on the dendrites of cerebellar Purkinje cells.¹ These fibers are the only output neurons of the cerebellar cortex and are critical to the coordination of motor movements, accounting for the ataxia experienced by patients with this subtype of PCD.² The link between Hodgkin lymphoma and PCA-Tr antibodies has been established; however, most reports involve men with a median age of 61 years with lymphoma-associated symptoms (such as lymphadenopathy) or systemic symptoms (fever, night sweats, or weight loss) preceding neurologic manifestations in 80% of cases.³

Our patient was a young, previously healthy adult female who initially presented with vertigo, a common concern with frequently benign origins. Although there was temporary resolution of symptoms after Epley maneuvers, symptoms recurred and progressed over several months to include brainstem manifestations of nystagmus, diplopia, and dysarthria. Previous reports indicate that after remission of the Hodgkin lymphoma, PCA-Tr antibodies disappear and symptoms can improve or resolve.^4,5 Treatment has just begun for our patient and although there has been initial clinical improvement, given the chronicity of symptoms, it is unclear if complete resolution will be achieved.

Conclusions

PCD can result in debilitating neurologic dysfunction and may be associated with malignancy such as Hodgkin lymphoma. This case offers unique insight due to the patient’s demographics and presentation, which involved brainstem pathology typically associated with late-onset disease and preceded by constitutional symptoms. Clinical suspicion of this rare disorder should be considered in all ages, especially if symptoms are progressive or neurologic manifestations arise, as early detection and treatment of the underlying malignancy are paramount to the prevention of significant disability.

Insulin injection therapy is one of the most widely used health care interventions to manage both type 1 and type 2 diabetes mellitus (T1DM/T2DM). Globally, more than 150 to 200 million people inject insulin into their upper posterior arms, buttocks, anterior and lateral thighs, or abdomen.^1,2 In an ideal world, every patient would be using the correct site and rotating their insulin injection sites in accordance with health care professional (HCP) recommendations—systematic injections in one general body location, at least 1 cm away from the previous injection.² Unfortunately, same-site insulin injection (repeatedly in the same region within 1 cm of previous injections) is a common mistake made by patients with DM—in one study, 63% of participants either did not rotate sites correctly or failed to do so at all.

Insulin-resistant cutaneous complications may occur as a result of same-site insulin injections. The most common is lipohypertrophy, reported in some studies in nearly 50% of patients with DM on insulin therapy.⁴ Other common cutaneous complications include lipoatrophy and amyloidosis. Injection-site acanthosis nigricans, although uncommon, has been reported in 18 cases in the literature.

Most articles suggest that same-site insulin injections decrease local insulin sensitivity and result in tissue hypertrophy because of the anabolic properties of insulin and increase in insulin binding to insulin-like growth factor-1 (IGF-1) receptor.^5-20 The hyperkeratotic growth and varying insulin absorption rates associated with these cutaneous complications increase chances of either hyper- or hypoglycemic episodes in patients.^10,11,13 It is the responsibility of the DM care professional to provide proper insulin-injection technique education and perform routine inspection of injection sites to reduce cutaneous complications of insulin therapy. The purpose of this article is to (1) describe a case of acanthosis nigricans resulting from insulin injection at the same site; (2) review case reports in the literature describing injection-site acanthosis nigricans resulting from same-site insulin injections; (3) describe localized cutaneous complications associated with the use of insulin; and (4) discuss clinical implications and lessons learned from the literature.

Case Presentation

A 75-year-old patient with an 8-year history of T2DM, as well as stable coronary artery disease, atrial fibrillation, hypertension, hyperlipidemia, chronic obstructive pulmonary disease, and stage 3 chronic kidney disease, presented with 2 discrete abdominal hyperpigmented plaques. At the time of the initial clinic visit, the patient was taking metformin 1000 mg twice daily and insulin glargine 40 units once daily. When insulin was initiated 7 years prior, the patient received neutral protamine Hagedorn (NPH) insulin for the first year and transitioned to insulin glargine. After 4 years of insulin therapy, insulin aspart was added and discontinued after 2 years. The patient’s hemoglobin A_1c (HbA_1c) was 6.8%, suggesting good glycemic control.

The patient reported 5 years of progressive, asymptomatic hyperpigmentation of the skin surrounding his insulin glargine injection sites and injecting in these same sites daily without rotation. He reported no additional skin changes or symptoms. He had noticed no skin changes while using NPH insulin during his first year of insulin therapy. On examination, the abdominal wall skin demonstrated 2 well-demarcated, nearly black, soft, velvety plaques, measuring 9 × 8 cm on the left side and 4 × 3.5 cm on the right, suggesting acanthosis nigricans (Figure 1A). The remainder of the skin examination, including the flexures, was normal. Of note, the patient received biweekly intramuscular testosterone injections in the gluteal region for secondary hypogonadism with no adverse dermatologic effects. A skin punch biopsy was performed and revealed epidermal papillomatosis and hyperkeratosis, confirming the clinical diagnosis of acanthosis nigricans (Figure 2).

After a review of insulin-injection technique at his clinic visit, the patient started rotating insulin injection sites over his entire abdomen, and the acanthosis nigricans partially improved. A few months later, the patient stopped rotating the insulin injection site, and the acanthosis nigricans worsened again. Because of worsening glycemic control, the patient was then started on insulin aspart. He did not develop any skin changes at the insulin aspart injection site, although he was not rotating its site of injection.

Subsequently, with reeducation and proper injection-site rotation, the patient had resolution of his acanthosis nigricans (Figure 1b).

Discussion

A review of the literature revealed 18 reported cases of acanthosis nigricans at sites of repeated insulin injection (Table).^5-20 Acanthosis nigricans at the site of insulin injection afflicts patients of any age, with cases observed in patients aged 14 to 75 years. Sixteen (84%) of 19 cases were male. Fourteen cases (73%) had T2DM; the rest of the patients had T1DM. The duration of insulin injection therapy prior to onset ranged from immediate to 13 years (median 4 years). Fourteen cases (73%) were reported on the abdomen; however, other sites, such as thighs and upper arm, also were reported. Lesions size varied from 12 to 360 cm². Two cases had associated amyloidosis. The average HbA_1c reported at presentation was 10%. Following insulin injection-site rotation, most of the cases reported improvement of both glycemic control and acanthosis nigricans appearance.

In the case described by Kudo and colleagues, a 59-year-old male patient with T2DM had been injecting insulin into the same spot on his abdomen for 10 years. He developed acanthosis nigricans and an amyloidoma so large and firm that it bent the needle when he injected insulin.¹¹

Most of the cases we found in the literature were after 2005 and associated with the use of human or analog insulin. These cases may be related to a bias, as cases may be easier to find in digital archives in the later years, when human or analog insulins have been in common use. Also noteworthy, in cases that reported dosage, most were not very high, and the highest daily dose was 240 IU/d. Ten reports of injection-site acanthosis nigricans were in dermatology journals; only 5 reports were in endocrinology journals and 3 in general medical journals, indicating possible less awareness of this phenomenon in other HCPs who care for patients with DM.

Complications of Same-Site Injections

Acanthosis nigricans. Commonly found in the armpits, neck folds, and groin, acanthosis nigricans is known as one of the calling cards for insulin resistance, obesity, and hyperinsulinemia.²¹ Acanthosis nigricans can be seen in people with or without DM and is not limited to those on insulin therapy. However, same-site insulin injections for 4 to 6 years also may result in injection-site acanthosis nigricans–like lesions because of factors such as insulin exposure at the local tissue level.¹⁶

Acanthosis nigricans development is characterized by hyperpigmented, hyperkeratotic, velvety, and sometimes verrucous plaques.⁶ Acanthosis nigricans surrounding repeated injection sites is hypothesized to develop as a result of localized hyperinsulinemia secondary to insulin resistance, which increases the stimulation of IGF, thereby causing epidermal hypertrophy.^5-20 If insulin injection therapy continues to be administered through the acanthosis nigricans lesion, it results in decreased insulin absorption, leading to poor glycemic control.¹³

Acanthosis nigricans associated with insulin injection is reversible. After rotation of injection sites, lesions either decrease in size or severity of appearance.^5-8,11 Also, by avoiding injection into the hyperkeratotic plaques and using normal subcutaneous tissue for injection, patients’ response to insulin improves, as measured by HbA_1c and by decreased daily insulin requirement.^{6-8,10,12,18-20}

Lipohypertrophy. This is characterized by an increase in localized adipose tissue and is the most common cutaneous complication of insulin therapy.² Lipohypertrophy presents as a firm, rubbery mass in the location of same-site insulin injections.²² Development of lipohypertrophy is suspected to be the result of either (1) anabolic effect of insulin on local adipocytes, promoting fat and protein synthesis; (2) an autoimmune response by immunoglobulin (Ig) G or IgE antibodies to insulin, immune response to insulin of different species, or to insulin injection techniques; or (3) repeated trauma to the injection site from repeated needle usage.^4,23

In a study assessing the prevalence of lipohypertrophy and its relation to insulin technique, 49.1% of participants with lipohypertrophy had glycemic variability compared with 6.5% of participants without lipohypertrophy.³ Johansson and colleagues described an impairment of insulin absorption in lipohypertrophic tissues, causing a 25% lower plasma insulin concentration compared with that of normal tissues.⁴ These findings suggest a significant effect of lipohypertrophy on insulin absorption—unnecessarily increasing insulin consumption and worsening glycemic control.

Primary prevention measures include injection site inspection and patient education about rotation and abstaining from needle reuse.²² If a patient already has signs of lipohypertrophy, data supports education and insulin injection technique practice as simple and effective means to reduce insulin action variability and increase glycemic control.²⁴

Lipoatrophy. Lipoatrophy is described as a local loss of subcutaneous adipose tissue often in the face, buttocks, legs and arm regions and can be rooted in genetic, immune, or drug-associated etiologies.²⁵ Insulin-induced lipoatrophy is suspected to be the result of tumor necrosis factor-α hyperproduction in reaction to insulin crystal presence at the injection site.^26,27 Overall, lipoatrophy development has decreased since the use of recombinant human insulin and analog insulin therapy.²⁸ The decrease is hypothesized to be due to increased subcutaneous tissue absorption rate of human insulin and its analog, decreasing overall adipocyte exposure to localized high insulin concentration.²⁷ Treatments for same-site insulin-derived lipoatrophy include changing injection sites and preparation of insulin.²⁶ When injection into the lipoatrophic site was avoided, glycemic control and lipoatrophy appearance improved.²⁶

Amyloidosis. Amyloidosis indicates the presence of an extracellular bundle of insoluble polymeric protein fibrils in tissues and organs.²⁹ Insulin-induced amyloidosis presents as a hard mass or ball near the injection site.²⁹ Insulin is one of many hormones that can form amyloid fibrils, and there have been several dozen cases reported of amyloid formation at the site of insulin injection.^29-31 Although insulin-derived amyloidosis is rare, it may be misdiagnosed as lipohypertrophy due to a lack of histopathologic testing or general awareness of the complication.²⁹

In a case series of 7 patients with amyloidosis, all patients had a mean HbA_1c of 9.3% (range, 8.5-10.2%) and averaged 1 IU/kg bodyweight before intervention.³⁰ After the discovery of the mass, participants were instructed to avoid injection into the amyloidoma, and average insulin requirements decreased to 0.48 IU/kg body weight (P = .40).³⁰ Patients with amyloidosis who rotated their injection sites experienced better glycemic control and decreased insulin requirements.³⁰

Pathophysiology of Localized Insulin Resistance

Insulin regulates glucose homeostasis in skeletal muscle and adipose tissue, increases hepatic and adipocyte lipid synthesis, and decreases adipocyte fatty acid release.³² Generalized insulin resistance occurs when target tissues have decreased glucose uptake in response to circulating insulin.³² Insulin resistance increases the amount of free insulin in surrounding tissues. At high concentrations, insulin fosters tissue growth by binding to IGF-1 receptors, stimulating hypertrophy and reproduction of keratinocytes and fibroblasts.³³ This pathophysiology helps explain the origin of localized acanthosis nigricans at same-site insulin injections.

Conclusions

Cutaneous complications are a local adverse effect of long-term failure to rotate insulin injection sites. Our case serves as a call to action for HCPs to improve education regarding insulin injection-site rotation, conduct routine injection-site inspection, and actively document cases as they occur to increase public awareness of these important complications.

If a patient with DM presents with unexplained poor glycemic control, consider questioning the patient about injection-site location and how often they are rotating the insulin injection site. Inspect the site for cutaneous complications. Of note, if a patient has a cutaneous complication due to insulin injection, adjust or decrease the insulin dosage when rotating sites to mitigate the risk of hypoglycemic episodes.

Improvement of glycemic control, cosmetic appearance of injection site, and insulin use all begin with skin inspection, injection technique education, and periodic review by a HCP.

Insulin injection therapy is one of the most widely used health care interventions to manage both type 1 and type 2 diabetes mellitus (T1DM/T2DM). Globally, more than 150 to 200 million people inject insulin into their upper posterior arms, buttocks, anterior and lateral thighs, or abdomen.^1,2 In an ideal world, every patient would be using the correct site and rotating their insulin injection sites in accordance with health care professional (HCP) recommendations—systematic injections in one general body location, at least 1 cm away from the previous injection.² Unfortunately, same-site insulin injection (repeatedly in the same region within 1 cm of previous injections) is a common mistake made by patients with DM—in one study, 63% of participants either did not rotate sites correctly or failed to do so at all.

Insulin-resistant cutaneous complications may occur as a result of same-site insulin injections. The most common is lipohypertrophy, reported in some studies in nearly 50% of patients with DM on insulin therapy.⁴ Other common cutaneous complications include lipoatrophy and amyloidosis. Injection-site acanthosis nigricans, although uncommon, has been reported in 18 cases in the literature.

Most articles suggest that same-site insulin injections decrease local insulin sensitivity and result in tissue hypertrophy because of the anabolic properties of insulin and increase in insulin binding to insulin-like growth factor-1 (IGF-1) receptor.^5-20 The hyperkeratotic growth and varying insulin absorption rates associated with these cutaneous complications increase chances of either hyper- or hypoglycemic episodes in patients.^10,11,13 It is the responsibility of the DM care professional to provide proper insulin-injection technique education and perform routine inspection of injection sites to reduce cutaneous complications of insulin therapy. The purpose of this article is to (1) describe a case of acanthosis nigricans resulting from insulin injection at the same site; (2) review case reports in the literature describing injection-site acanthosis nigricans resulting from same-site insulin injections; (3) describe localized cutaneous complications associated with the use of insulin; and (4) discuss clinical implications and lessons learned from the literature.

Case Presentation

A 75-year-old patient with an 8-year history of T2DM, as well as stable coronary artery disease, atrial fibrillation, hypertension, hyperlipidemia, chronic obstructive pulmonary disease, and stage 3 chronic kidney disease, presented with 2 discrete abdominal hyperpigmented plaques. At the time of the initial clinic visit, the patient was taking metformin 1000 mg twice daily and insulin glargine 40 units once daily. When insulin was initiated 7 years prior, the patient received neutral protamine Hagedorn (NPH) insulin for the first year and transitioned to insulin glargine. After 4 years of insulin therapy, insulin aspart was added and discontinued after 2 years. The patient’s hemoglobin A_1c (HbA_1c) was 6.8%, suggesting good glycemic control.

The patient reported 5 years of progressive, asymptomatic hyperpigmentation of the skin surrounding his insulin glargine injection sites and injecting in these same sites daily without rotation. He reported no additional skin changes or symptoms. He had noticed no skin changes while using NPH insulin during his first year of insulin therapy. On examination, the abdominal wall skin demonstrated 2 well-demarcated, nearly black, soft, velvety plaques, measuring 9 × 8 cm on the left side and 4 × 3.5 cm on the right, suggesting acanthosis nigricans (Figure 1A). The remainder of the skin examination, including the flexures, was normal. Of note, the patient received biweekly intramuscular testosterone injections in the gluteal region for secondary hypogonadism with no adverse dermatologic effects. A skin punch biopsy was performed and revealed epidermal papillomatosis and hyperkeratosis, confirming the clinical diagnosis of acanthosis nigricans (Figure 2).

After a review of insulin-injection technique at his clinic visit, the patient started rotating insulin injection sites over his entire abdomen, and the acanthosis nigricans partially improved. A few months later, the patient stopped rotating the insulin injection site, and the acanthosis nigricans worsened again. Because of worsening glycemic control, the patient was then started on insulin aspart. He did not develop any skin changes at the insulin aspart injection site, although he was not rotating its site of injection.

Subsequently, with reeducation and proper injection-site rotation, the patient had resolution of his acanthosis nigricans (Figure 1b).

Discussion

A review of the literature revealed 18 reported cases of acanthosis nigricans at sites of repeated insulin injection (Table).^5-20 Acanthosis nigricans at the site of insulin injection afflicts patients of any age, with cases observed in patients aged 14 to 75 years. Sixteen (84%) of 19 cases were male. Fourteen cases (73%) had T2DM; the rest of the patients had T1DM. The duration of insulin injection therapy prior to onset ranged from immediate to 13 years (median 4 years). Fourteen cases (73%) were reported on the abdomen; however, other sites, such as thighs and upper arm, also were reported. Lesions size varied from 12 to 360 cm². Two cases had associated amyloidosis. The average HbA_1c reported at presentation was 10%. Following insulin injection-site rotation, most of the cases reported improvement of both glycemic control and acanthosis nigricans appearance.

In the case described by Kudo and colleagues, a 59-year-old male patient with T2DM had been injecting insulin into the same spot on his abdomen for 10 years. He developed acanthosis nigricans and an amyloidoma so large and firm that it bent the needle when he injected insulin.¹¹

Most of the cases we found in the literature were after 2005 and associated with the use of human or analog insulin. These cases may be related to a bias, as cases may be easier to find in digital archives in the later years, when human or analog insulins have been in common use. Also noteworthy, in cases that reported dosage, most were not very high, and the highest daily dose was 240 IU/d. Ten reports of injection-site acanthosis nigricans were in dermatology journals; only 5 reports were in endocrinology journals and 3 in general medical journals, indicating possible less awareness of this phenomenon in other HCPs who care for patients with DM.

Complications of Same-Site Injections

Acanthosis nigricans. Commonly found in the armpits, neck folds, and groin, acanthosis nigricans is known as one of the calling cards for insulin resistance, obesity, and hyperinsulinemia.²¹ Acanthosis nigricans can be seen in people with or without DM and is not limited to those on insulin therapy. However, same-site insulin injections for 4 to 6 years also may result in injection-site acanthosis nigricans–like lesions because of factors such as insulin exposure at the local tissue level.¹⁶

Acanthosis nigricans development is characterized by hyperpigmented, hyperkeratotic, velvety, and sometimes verrucous plaques.⁶ Acanthosis nigricans surrounding repeated injection sites is hypothesized to develop as a result of localized hyperinsulinemia secondary to insulin resistance, which increases the stimulation of IGF, thereby causing epidermal hypertrophy.^5-20 If insulin injection therapy continues to be administered through the acanthosis nigricans lesion, it results in decreased insulin absorption, leading to poor glycemic control.¹³

Acanthosis nigricans associated with insulin injection is reversible. After rotation of injection sites, lesions either decrease in size or severity of appearance.^5-8,11 Also, by avoiding injection into the hyperkeratotic plaques and using normal subcutaneous tissue for injection, patients’ response to insulin improves, as measured by HbA_1c and by decreased daily insulin requirement.^{6-8,10,12,18-20}

Lipohypertrophy. This is characterized by an increase in localized adipose tissue and is the most common cutaneous complication of insulin therapy.² Lipohypertrophy presents as a firm, rubbery mass in the location of same-site insulin injections.²² Development of lipohypertrophy is suspected to be the result of either (1) anabolic effect of insulin on local adipocytes, promoting fat and protein synthesis; (2) an autoimmune response by immunoglobulin (Ig) G or IgE antibodies to insulin, immune response to insulin of different species, or to insulin injection techniques; or (3) repeated trauma to the injection site from repeated needle usage.^4,23

In a study assessing the prevalence of lipohypertrophy and its relation to insulin technique, 49.1% of participants with lipohypertrophy had glycemic variability compared with 6.5% of participants without lipohypertrophy.³ Johansson and colleagues described an impairment of insulin absorption in lipohypertrophic tissues, causing a 25% lower plasma insulin concentration compared with that of normal tissues.⁴ These findings suggest a significant effect of lipohypertrophy on insulin absorption—unnecessarily increasing insulin consumption and worsening glycemic control.

Primary prevention measures include injection site inspection and patient education about rotation and abstaining from needle reuse.²² If a patient already has signs of lipohypertrophy, data supports education and insulin injection technique practice as simple and effective means to reduce insulin action variability and increase glycemic control.²⁴

Lipoatrophy. Lipoatrophy is described as a local loss of subcutaneous adipose tissue often in the face, buttocks, legs and arm regions and can be rooted in genetic, immune, or drug-associated etiologies.²⁵ Insulin-induced lipoatrophy is suspected to be the result of tumor necrosis factor-α hyperproduction in reaction to insulin crystal presence at the injection site.^26,27 Overall, lipoatrophy development has decreased since the use of recombinant human insulin and analog insulin therapy.²⁸ The decrease is hypothesized to be due to increased subcutaneous tissue absorption rate of human insulin and its analog, decreasing overall adipocyte exposure to localized high insulin concentration.²⁷ Treatments for same-site insulin-derived lipoatrophy include changing injection sites and preparation of insulin.²⁶ When injection into the lipoatrophic site was avoided, glycemic control and lipoatrophy appearance improved.²⁶

Amyloidosis. Amyloidosis indicates the presence of an extracellular bundle of insoluble polymeric protein fibrils in tissues and organs.²⁹ Insulin-induced amyloidosis presents as a hard mass or ball near the injection site.²⁹ Insulin is one of many hormones that can form amyloid fibrils, and there have been several dozen cases reported of amyloid formation at the site of insulin injection.^29-31 Although insulin-derived amyloidosis is rare, it may be misdiagnosed as lipohypertrophy due to a lack of histopathologic testing or general awareness of the complication.²⁹

In a case series of 7 patients with amyloidosis, all patients had a mean HbA_1c of 9.3% (range, 8.5-10.2%) and averaged 1 IU/kg bodyweight before intervention.³⁰ After the discovery of the mass, participants were instructed to avoid injection into the amyloidoma, and average insulin requirements decreased to 0.48 IU/kg body weight (P = .40).³⁰ Patients with amyloidosis who rotated their injection sites experienced better glycemic control and decreased insulin requirements.³⁰

Pathophysiology of Localized Insulin Resistance

Insulin regulates glucose homeostasis in skeletal muscle and adipose tissue, increases hepatic and adipocyte lipid synthesis, and decreases adipocyte fatty acid release.³² Generalized insulin resistance occurs when target tissues have decreased glucose uptake in response to circulating insulin.³² Insulin resistance increases the amount of free insulin in surrounding tissues. At high concentrations, insulin fosters tissue growth by binding to IGF-1 receptors, stimulating hypertrophy and reproduction of keratinocytes and fibroblasts.³³ This pathophysiology helps explain the origin of localized acanthosis nigricans at same-site insulin injections.

Conclusions

Cutaneous complications are a local adverse effect of long-term failure to rotate insulin injection sites. Our case serves as a call to action for HCPs to improve education regarding insulin injection-site rotation, conduct routine injection-site inspection, and actively document cases as they occur to increase public awareness of these important complications.

If a patient with DM presents with unexplained poor glycemic control, consider questioning the patient about injection-site location and how often they are rotating the insulin injection site. Inspect the site for cutaneous complications. Of note, if a patient has a cutaneous complication due to insulin injection, adjust or decrease the insulin dosage when rotating sites to mitigate the risk of hypoglycemic episodes.

Improvement of glycemic control, cosmetic appearance of injection site, and insulin use all begin with skin inspection, injection technique education, and periodic review by a HCP.

Insulin injection therapy is one of the most widely used health care interventions to manage both type 1 and type 2 diabetes mellitus (T1DM/T2DM). Globally, more than 150 to 200 million people inject insulin into their upper posterior arms, buttocks, anterior and lateral thighs, or abdomen.^1,2 In an ideal world, every patient would be using the correct site and rotating their insulin injection sites in accordance with health care professional (HCP) recommendations—systematic injections in one general body location, at least 1 cm away from the previous injection.² Unfortunately, same-site insulin injection (repeatedly in the same region within 1 cm of previous injections) is a common mistake made by patients with DM—in one study, 63% of participants either did not rotate sites correctly or failed to do so at all.

Insulin-resistant cutaneous complications may occur as a result of same-site insulin injections. The most common is lipohypertrophy, reported in some studies in nearly 50% of patients with DM on insulin therapy.⁴ Other common cutaneous complications include lipoatrophy and amyloidosis. Injection-site acanthosis nigricans, although uncommon, has been reported in 18 cases in the literature.

Most articles suggest that same-site insulin injections decrease local insulin sensitivity and result in tissue hypertrophy because of the anabolic properties of insulin and increase in insulin binding to insulin-like growth factor-1 (IGF-1) receptor.^5-20 The hyperkeratotic growth and varying insulin absorption rates associated with these cutaneous complications increase chances of either hyper- or hypoglycemic episodes in patients.^10,11,13 It is the responsibility of the DM care professional to provide proper insulin-injection technique education and perform routine inspection of injection sites to reduce cutaneous complications of insulin therapy. The purpose of this article is to (1) describe a case of acanthosis nigricans resulting from insulin injection at the same site; (2) review case reports in the literature describing injection-site acanthosis nigricans resulting from same-site insulin injections; (3) describe localized cutaneous complications associated with the use of insulin; and (4) discuss clinical implications and lessons learned from the literature.

Case Presentation

A 75-year-old patient with an 8-year history of T2DM, as well as stable coronary artery disease, atrial fibrillation, hypertension, hyperlipidemia, chronic obstructive pulmonary disease, and stage 3 chronic kidney disease, presented with 2 discrete abdominal hyperpigmented plaques. At the time of the initial clinic visit, the patient was taking metformin 1000 mg twice daily and insulin glargine 40 units once daily. When insulin was initiated 7 years prior, the patient received neutral protamine Hagedorn (NPH) insulin for the first year and transitioned to insulin glargine. After 4 years of insulin therapy, insulin aspart was added and discontinued after 2 years. The patient’s hemoglobin A_1c (HbA_1c) was 6.8%, suggesting good glycemic control.

The patient reported 5 years of progressive, asymptomatic hyperpigmentation of the skin surrounding his insulin glargine injection sites and injecting in these same sites daily without rotation. He reported no additional skin changes or symptoms. He had noticed no skin changes while using NPH insulin during his first year of insulin therapy. On examination, the abdominal wall skin demonstrated 2 well-demarcated, nearly black, soft, velvety plaques, measuring 9 × 8 cm on the left side and 4 × 3.5 cm on the right, suggesting acanthosis nigricans (Figure 1A). The remainder of the skin examination, including the flexures, was normal. Of note, the patient received biweekly intramuscular testosterone injections in the gluteal region for secondary hypogonadism with no adverse dermatologic effects. A skin punch biopsy was performed and revealed epidermal papillomatosis and hyperkeratosis, confirming the clinical diagnosis of acanthosis nigricans (Figure 2).

After a review of insulin-injection technique at his clinic visit, the patient started rotating insulin injection sites over his entire abdomen, and the acanthosis nigricans partially improved. A few months later, the patient stopped rotating the insulin injection site, and the acanthosis nigricans worsened again. Because of worsening glycemic control, the patient was then started on insulin aspart. He did not develop any skin changes at the insulin aspart injection site, although he was not rotating its site of injection.

Subsequently, with reeducation and proper injection-site rotation, the patient had resolution of his acanthosis nigricans (Figure 1b).

Discussion

A review of the literature revealed 18 reported cases of acanthosis nigricans at sites of repeated insulin injection (Table).^5-20 Acanthosis nigricans at the site of insulin injection afflicts patients of any age, with cases observed in patients aged 14 to 75 years. Sixteen (84%) of 19 cases were male. Fourteen cases (73%) had T2DM; the rest of the patients had T1DM. The duration of insulin injection therapy prior to onset ranged from immediate to 13 years (median 4 years). Fourteen cases (73%) were reported on the abdomen; however, other sites, such as thighs and upper arm, also were reported. Lesions size varied from 12 to 360 cm². Two cases had associated amyloidosis. The average HbA_1c reported at presentation was 10%. Following insulin injection-site rotation, most of the cases reported improvement of both glycemic control and acanthosis nigricans appearance.

In the case described by Kudo and colleagues, a 59-year-old male patient with T2DM had been injecting insulin into the same spot on his abdomen for 10 years. He developed acanthosis nigricans and an amyloidoma so large and firm that it bent the needle when he injected insulin.¹¹

Most of the cases we found in the literature were after 2005 and associated with the use of human or analog insulin. These cases may be related to a bias, as cases may be easier to find in digital archives in the later years, when human or analog insulins have been in common use. Also noteworthy, in cases that reported dosage, most were not very high, and the highest daily dose was 240 IU/d. Ten reports of injection-site acanthosis nigricans were in dermatology journals; only 5 reports were in endocrinology journals and 3 in general medical journals, indicating possible less awareness of this phenomenon in other HCPs who care for patients with DM.

Complications of Same-Site Injections

Acanthosis nigricans. Commonly found in the armpits, neck folds, and groin, acanthosis nigricans is known as one of the calling cards for insulin resistance, obesity, and hyperinsulinemia.²¹ Acanthosis nigricans can be seen in people with or without DM and is not limited to those on insulin therapy. However, same-site insulin injections for 4 to 6 years also may result in injection-site acanthosis nigricans–like lesions because of factors such as insulin exposure at the local tissue level.¹⁶

Acanthosis nigricans development is characterized by hyperpigmented, hyperkeratotic, velvety, and sometimes verrucous plaques.⁶ Acanthosis nigricans surrounding repeated injection sites is hypothesized to develop as a result of localized hyperinsulinemia secondary to insulin resistance, which increases the stimulation of IGF, thereby causing epidermal hypertrophy.^5-20 If insulin injection therapy continues to be administered through the acanthosis nigricans lesion, it results in decreased insulin absorption, leading to poor glycemic control.¹³

Acanthosis nigricans associated with insulin injection is reversible. After rotation of injection sites, lesions either decrease in size or severity of appearance.^5-8,11 Also, by avoiding injection into the hyperkeratotic plaques and using normal subcutaneous tissue for injection, patients’ response to insulin improves, as measured by HbA_1c and by decreased daily insulin requirement.^{6-8,10,12,18-20}

Lipohypertrophy. This is characterized by an increase in localized adipose tissue and is the most common cutaneous complication of insulin therapy.² Lipohypertrophy presents as a firm, rubbery mass in the location of same-site insulin injections.²² Development of lipohypertrophy is suspected to be the result of either (1) anabolic effect of insulin on local adipocytes, promoting fat and protein synthesis; (2) an autoimmune response by immunoglobulin (Ig) G or IgE antibodies to insulin, immune response to insulin of different species, or to insulin injection techniques; or (3) repeated trauma to the injection site from repeated needle usage.^4,23

In a study assessing the prevalence of lipohypertrophy and its relation to insulin technique, 49.1% of participants with lipohypertrophy had glycemic variability compared with 6.5% of participants without lipohypertrophy.³ Johansson and colleagues described an impairment of insulin absorption in lipohypertrophic tissues, causing a 25% lower plasma insulin concentration compared with that of normal tissues.⁴ These findings suggest a significant effect of lipohypertrophy on insulin absorption—unnecessarily increasing insulin consumption and worsening glycemic control.

Primary prevention measures include injection site inspection and patient education about rotation and abstaining from needle reuse.²² If a patient already has signs of lipohypertrophy, data supports education and insulin injection technique practice as simple and effective means to reduce insulin action variability and increase glycemic control.²⁴

Lipoatrophy. Lipoatrophy is described as a local loss of subcutaneous adipose tissue often in the face, buttocks, legs and arm regions and can be rooted in genetic, immune, or drug-associated etiologies.²⁵ Insulin-induced lipoatrophy is suspected to be the result of tumor necrosis factor-α hyperproduction in reaction to insulin crystal presence at the injection site.^26,27 Overall, lipoatrophy development has decreased since the use of recombinant human insulin and analog insulin therapy.²⁸ The decrease is hypothesized to be due to increased subcutaneous tissue absorption rate of human insulin and its analog, decreasing overall adipocyte exposure to localized high insulin concentration.²⁷ Treatments for same-site insulin-derived lipoatrophy include changing injection sites and preparation of insulin.²⁶ When injection into the lipoatrophic site was avoided, glycemic control and lipoatrophy appearance improved.²⁶

Amyloidosis. Amyloidosis indicates the presence of an extracellular bundle of insoluble polymeric protein fibrils in tissues and organs.²⁹ Insulin-induced amyloidosis presents as a hard mass or ball near the injection site.²⁹ Insulin is one of many hormones that can form amyloid fibrils, and there have been several dozen cases reported of amyloid formation at the site of insulin injection.^29-31 Although insulin-derived amyloidosis is rare, it may be misdiagnosed as lipohypertrophy due to a lack of histopathologic testing or general awareness of the complication.²⁹

In a case series of 7 patients with amyloidosis, all patients had a mean HbA_1c of 9.3% (range, 8.5-10.2%) and averaged 1 IU/kg bodyweight before intervention.³⁰ After the discovery of the mass, participants were instructed to avoid injection into the amyloidoma, and average insulin requirements decreased to 0.48 IU/kg body weight (P = .40).³⁰ Patients with amyloidosis who rotated their injection sites experienced better glycemic control and decreased insulin requirements.³⁰

Pathophysiology of Localized Insulin Resistance

Insulin regulates glucose homeostasis in skeletal muscle and adipose tissue, increases hepatic and adipocyte lipid synthesis, and decreases adipocyte fatty acid release.³² Generalized insulin resistance occurs when target tissues have decreased glucose uptake in response to circulating insulin.³² Insulin resistance increases the amount of free insulin in surrounding tissues. At high concentrations, insulin fosters tissue growth by binding to IGF-1 receptors, stimulating hypertrophy and reproduction of keratinocytes and fibroblasts.³³ This pathophysiology helps explain the origin of localized acanthosis nigricans at same-site insulin injections.

Conclusions

Cutaneous complications are a local adverse effect of long-term failure to rotate insulin injection sites. Our case serves as a call to action for HCPs to improve education regarding insulin injection-site rotation, conduct routine injection-site inspection, and actively document cases as they occur to increase public awareness of these important complications.

If a patient with DM presents with unexplained poor glycemic control, consider questioning the patient about injection-site location and how often they are rotating the insulin injection site. Inspect the site for cutaneous complications. Of note, if a patient has a cutaneous complication due to insulin injection, adjust or decrease the insulin dosage when rotating sites to mitigate the risk of hypoglycemic episodes.

Improvement of glycemic control, cosmetic appearance of injection site, and insulin use all begin with skin inspection, injection technique education, and periodic review by a HCP.

Pancytopenia is a condition in which all 3 hematologic cell lines are lower than expected in the blood, often representing either an increase in cellular destruction or decrease in bone marrow production. Destruction often occurs in the setting of autoimmune conditions (eg, systemic lupus erythematosus, rheumatoid arthritis) or splenic sequestration, often affecting erythrocytes and platelets more than leukocytes. Decreased production represents central etiologies, which are often due to nutritional deficiencies, infections, drug toxicities, or malabsorption.¹ Pancytopenia secondary to vitamin B₁₂ deficiency is rare, accounting for about 5% of the hematologic manifestations of symptomatic vitamin B₁₂ deficient patients.²

Pernicious anemia, named for a once lethal disease, is a form of vitamin B₁₂ (cobalamin) deficiency that results from an autoimmune (type II hypersensitivity) reaction to gastric parietal cells or intrinsic factor. Antibodies bind to gastric parietal cells and reduce gastric acid production, leading to atrophic gastritis, or they bind intrinsic factor and block the binding and absorption of vitamin B₁₂ in the gastrointestinal tract. While first described in the 1820s, it was not until a century later when scientists were studying hematopoiesis in response to the heavy casualty burden from battlefield exsanguination in World War I that dogs fed raw liver were noted to have significantly better blood regeneration response than those fed cooked liver. This discovery led physicians Minot and Murphy to use raw liver to treat pernicious anemia and found that jaundice improved, reticulocyte counts increased, and hemoglobin (Hb) concentration improved, resulting in the duo becoming the first American recipients of the Nobel Prize in physiology or medicine.³ It was ultimately determined in 1948 by chemists Folkers and Todd that the active ingredient in raw liver responsible for this phenomenon was vitamin B₁₂.⁴

Case Presentation

A 24-year-old active-duty female patient presented in late December 2020 to a theater hospital in Djibouti after a witnessed syncopal episode. She had a history of Hashimoto thyroiditis and was taking levothyroxine sodium 75 mcg daily. The patient reported gluten intolerance, which was never formally evaluated. The syncopal episode lasted a few seconds and was not associated with any prodromal or postictal symptoms. No seizure activity was observed, and she had no history of syncopal episodes. She reported that she had been feeling ill 24 to 48 hours prior, with nausea, fatigue, decreased oral intake, decreased urine output, and 2 episodes of nonbilious, nonbloody emesis.

When the patient arrived, she was tachycardic with heart rate in the 130s beats per minute (baseline, 100-110 beats per minute), febrile (103 °F), and had systolic blood pressure (SBP) in the low 100s (baseline, SBP 120s-130s). An electrocardiogram and chest radiographs were unremarkable. Her complete blood count (CBC) could not be processed due to Hb and platelet levels too low to detect on assay (Table 2). Lactate dehydrogenase (LDH) was elevated at > 1000 U/L with mild elevation in liver enzymes (aspartate aminotransferase, 98 U/L; alanine aminotransferase, 51 U/L) and prolonged partial thromboplastin time 70 seconds. She did not report any increased bleeding or bruising. The peripheral blood smear demonstrated pancytopenia, without any schistocytes, and she was started on broad-spectrum antibiotics for presumed sepsis from urinary source and possible TTP.

The patient received 5 units of packed red blood cells, transfusion of platelets, and 2 doses of vitamin B₁₂ in Djibouti with clinical improvement and resolution of orthostasis, hypotension, tachycardia, and fever. Her final posttransfusion CBC showed a Hb level of 11.2 g/dL, white blood cell (WBC) count of 1.7 K/µL, and platelet count of 23 K/µL (Table 3). Two days later her Hb level was 9.0 g/dL, WBC count 1.8 K/µL, and platelet count was 12 K/µL. She was evacuated via air to Landstuhl Regional Medical Center (LRMC) in Germany within 48 hours of presentation, given limited testing capabilities and persistent anemia and thrombocytopenia, refractory to transfusion, concerning for aplastic anemia or acute leukemia.

On arrival at LRMC, she was transfused 1 unit of platelets and given 3 doses of intramuscular vitamin B₁₂ for undetectable levels (< 50 pg/mL) at presentation. An extensive infectious workup was obtained, which did not reveal any viral, bacterial, or parasitic causes. The patient also had a bone marrow biopsy performed at a civilian site, which revealed hypocellular bone marrow. She was transferred to Walter Reed National Military Medical Center (WRNMMC) for further workup and evaluation, given the infectious workup, which was negative. Concern for hematologic malignancy remained. At the time of her arrival, the laboratory values had drastically improved with vitamin supplementation. The patient’s absolute reticulocyte count indicated adequate bone marrow response and because of her improvement, a repeat bone marrow biopsy was not performed.

Intrinsic factor antibodies were elevated (34.5 AU/mL; reference range, 0.0-1.1), which confirmed that this patient’s underlying etiology was secondary to pernicious anemia. The patient continued to improve and repeat vitamin B₁₂ and folate levels revealed that she was responding to therapy. At discharge, intramuscular vitamin B₁₂ injections were planned to continue monthly, indefinitely per guidelines. Oral supplementation is typically avoided due to poor absorption.

Of note, during her inpatient admission at WRNMMC, further evaluation of reported gluten intolerance was performed, which revealed a negative celiac disease panel (IgG/IgA tissue transglutaminase antibodies). On discharge, she was to establish care with gastroenterology for further evaluation, likely including endoscopic evaluation, at her next duty station. She was able to resume full travel and duty functions on discharge from WRNMMC.

Discussion

We highlight a complex case of pancytopenia secondary to pernicious anemia in a deployed service member. With limited resources downrange, the workup of pancytopenia can be resource intensive, expensive, and time sensitive, which can have detrimental impacts on medical readiness. Additionally, undiagnosed coagulopathies can have lethal consequences in a deployed service member where bleeding risk may be elevated depending on the mission. The differential for pancytopenia is vast, and given its relative rarity in pernicious anemia, the HCP must use key components of the history and laboratory results to narrow the differential (eAppendix).¹⁰

Pernicious anemia commonly presents as an isolated anemia. In a study looking at the hematologic manifestations of 201 cohort patients with well-documented vitamin B₁₂ deficiency, 5% had symptomatic pancytopenia and 1.5% had a hemolytic anemia.² The majority (> 67%) of hematologic abnormalities were correctable with cobalamin replacement.² In our case, the solider presented with symptomatic anemia, manifesting as syncope, and was found to have transfusion-resistant pancytopenia.She had a hemolytic anemia with an LDH > 1000 U/L, haptoglobin < 3 mg/dL, and mild transaminitis with hyperbilirubinemia (1.8 mg/dL). No schistocytes were observed on peripheral smear, suggesting intramedullary hemolysis, which is believed to be due to the destruction of megaloblastic cells by macrophages in bone marrow.¹¹ A French study found high LDH levels and low reticulocyte counts to be strongly suggestive of vitamin B₁₂ deficiency and helpful in differentiating pernicious anemia from TTP, given that bone marrow response to anemia in TTP is preserved.⁸

While vitamin B₁₂ deficiency is not often associated with hemolytic anemia, multiple cases have been reported in the literature.⁶ Screening for vitamin B₁₂ deficiency may have shortened this patient’s clinical course and limited the need for air evacuation to a stateside quaternary medical center. However, testing for cobalamin levels in overseas deployed environments is difficult, timely, and costly. New technologies, such as optical sensors, can detect vitamin B₁₂ levels in the blood in < 1 minute and offer portable, low-cost options that may be useful in the deployed military setting.¹²

Diet plays a key role in this case, since the patient had a reported history of gluten intolerance, although it was never documented or evaluated prior to this presentation. Prior to deployment, the patient ate mostly rice, potatoes, and vegetables. While deployed in an austere environment, food options were limited. These conditions forced her to intermittently consume gluten products, which led to gastrointestinal issues, exacerbating her nutritional deficiencies. In the 2 months before her first syncopal episode, she reported worsening fatigue that impacted her ability to exercise. Vitamin B₁₂ stores often take years to deplete, suggesting that she had a chronic nutritional deficiency before deployment. Another possibility was that she developed an autoimmune gastritis that acutely worsened in the setting of poor nutritional intake. Her history of Hashimoto thyroiditis is also important, as up to one-third of patients with autoimmune thyroid disease have been associated with pernicious anemia (range, 3%-32%) with certain shared human leukocyte antigen alleles implicated in autoimmune gastritis.^13,14

Conclusions

This rare case of pernicious anemia presenting as pancytopenia illustrates the challenge in working up pancytopenia, especially in austere military environments with limited testing capabilities. Screening for chronic dietary and nutritional deficiency is important in a service member, raising the question of what role predeployment screening may have and what dietary accommodations may be available during overseas deployments, which can potentially dampen inflammation of the gastrointestinal tract, especially for those with preexisting autoimmune gastrointestinal conditions. Also, newer technology allows portable, low-cost testing of cobalamin and may aid in its diagnosis. In patients who are anemic with low vitamin B₁₂, HCPs can begin vitamin B₁₂ supplementation while continuing the workup (eg, antibody testing, endoscopy). If the patient responds appropriately, further workup becomes less urgent, therefore, decreasing resource use and increasing military readiness. When hemolysis is present, a low reticulocyte count can be beneficial to help differentiate this condition from TTP, a life-threatening condition that must also be ruled out or treated. Pernicious anemia should be on the differential in any patients with autoimmune conditions presenting with cytopenias, especially in those with a history of autoimmune thyroid disorders.

Pancytopenia is a condition in which all 3 hematologic cell lines are lower than expected in the blood, often representing either an increase in cellular destruction or decrease in bone marrow production. Destruction often occurs in the setting of autoimmune conditions (eg, systemic lupus erythematosus, rheumatoid arthritis) or splenic sequestration, often affecting erythrocytes and platelets more than leukocytes. Decreased production represents central etiologies, which are often due to nutritional deficiencies, infections, drug toxicities, or malabsorption.¹ Pancytopenia secondary to vitamin B₁₂ deficiency is rare, accounting for about 5% of the hematologic manifestations of symptomatic vitamin B₁₂ deficient patients.²

Pernicious anemia, named for a once lethal disease, is a form of vitamin B₁₂ (cobalamin) deficiency that results from an autoimmune (type II hypersensitivity) reaction to gastric parietal cells or intrinsic factor. Antibodies bind to gastric parietal cells and reduce gastric acid production, leading to atrophic gastritis, or they bind intrinsic factor and block the binding and absorption of vitamin B₁₂ in the gastrointestinal tract. While first described in the 1820s, it was not until a century later when scientists were studying hematopoiesis in response to the heavy casualty burden from battlefield exsanguination in World War I that dogs fed raw liver were noted to have significantly better blood regeneration response than those fed cooked liver. This discovery led physicians Minot and Murphy to use raw liver to treat pernicious anemia and found that jaundice improved, reticulocyte counts increased, and hemoglobin (Hb) concentration improved, resulting in the duo becoming the first American recipients of the Nobel Prize in physiology or medicine.³ It was ultimately determined in 1948 by chemists Folkers and Todd that the active ingredient in raw liver responsible for this phenomenon was vitamin B₁₂.⁴

Case Presentation

A 24-year-old active-duty female patient presented in late December 2020 to a theater hospital in Djibouti after a witnessed syncopal episode. She had a history of Hashimoto thyroiditis and was taking levothyroxine sodium 75 mcg daily. The patient reported gluten intolerance, which was never formally evaluated. The syncopal episode lasted a few seconds and was not associated with any prodromal or postictal symptoms. No seizure activity was observed, and she had no history of syncopal episodes. She reported that she had been feeling ill 24 to 48 hours prior, with nausea, fatigue, decreased oral intake, decreased urine output, and 2 episodes of nonbilious, nonbloody emesis.

When the patient arrived, she was tachycardic with heart rate in the 130s beats per minute (baseline, 100-110 beats per minute), febrile (103 °F), and had systolic blood pressure (SBP) in the low 100s (baseline, SBP 120s-130s). An electrocardiogram and chest radiographs were unremarkable. Her complete blood count (CBC) could not be processed due to Hb and platelet levels too low to detect on assay (Table 2). Lactate dehydrogenase (LDH) was elevated at > 1000 U/L with mild elevation in liver enzymes (aspartate aminotransferase, 98 U/L; alanine aminotransferase, 51 U/L) and prolonged partial thromboplastin time 70 seconds. She did not report any increased bleeding or bruising. The peripheral blood smear demonstrated pancytopenia, without any schistocytes, and she was started on broad-spectrum antibiotics for presumed sepsis from urinary source and possible TTP.

The patient received 5 units of packed red blood cells, transfusion of platelets, and 2 doses of vitamin B₁₂ in Djibouti with clinical improvement and resolution of orthostasis, hypotension, tachycardia, and fever. Her final posttransfusion CBC showed a Hb level of 11.2 g/dL, white blood cell (WBC) count of 1.7 K/µL, and platelet count of 23 K/µL (Table 3). Two days later her Hb level was 9.0 g/dL, WBC count 1.8 K/µL, and platelet count was 12 K/µL. She was evacuated via air to Landstuhl Regional Medical Center (LRMC) in Germany within 48 hours of presentation, given limited testing capabilities and persistent anemia and thrombocytopenia, refractory to transfusion, concerning for aplastic anemia or acute leukemia.

On arrival at LRMC, she was transfused 1 unit of platelets and given 3 doses of intramuscular vitamin B₁₂ for undetectable levels (< 50 pg/mL) at presentation. An extensive infectious workup was obtained, which did not reveal any viral, bacterial, or parasitic causes. The patient also had a bone marrow biopsy performed at a civilian site, which revealed hypocellular bone marrow. She was transferred to Walter Reed National Military Medical Center (WRNMMC) for further workup and evaluation, given the infectious workup, which was negative. Concern for hematologic malignancy remained. At the time of her arrival, the laboratory values had drastically improved with vitamin supplementation. The patient’s absolute reticulocyte count indicated adequate bone marrow response and because of her improvement, a repeat bone marrow biopsy was not performed.

Intrinsic factor antibodies were elevated (34.5 AU/mL; reference range, 0.0-1.1), which confirmed that this patient’s underlying etiology was secondary to pernicious anemia. The patient continued to improve and repeat vitamin B₁₂ and folate levels revealed that she was responding to therapy. At discharge, intramuscular vitamin B₁₂ injections were planned to continue monthly, indefinitely per guidelines. Oral supplementation is typically avoided due to poor absorption.

Of note, during her inpatient admission at WRNMMC, further evaluation of reported gluten intolerance was performed, which revealed a negative celiac disease panel (IgG/IgA tissue transglutaminase antibodies). On discharge, she was to establish care with gastroenterology for further evaluation, likely including endoscopic evaluation, at her next duty station. She was able to resume full travel and duty functions on discharge from WRNMMC.

Discussion

We highlight a complex case of pancytopenia secondary to pernicious anemia in a deployed service member. With limited resources downrange, the workup of pancytopenia can be resource intensive, expensive, and time sensitive, which can have detrimental impacts on medical readiness. Additionally, undiagnosed coagulopathies can have lethal consequences in a deployed service member where bleeding risk may be elevated depending on the mission. The differential for pancytopenia is vast, and given its relative rarity in pernicious anemia, the HCP must use key components of the history and laboratory results to narrow the differential (eAppendix).¹⁰

Pernicious anemia commonly presents as an isolated anemia. In a study looking at the hematologic manifestations of 201 cohort patients with well-documented vitamin B₁₂ deficiency, 5% had symptomatic pancytopenia and 1.5% had a hemolytic anemia.² The majority (> 67%) of hematologic abnormalities were correctable with cobalamin replacement.² In our case, the solider presented with symptomatic anemia, manifesting as syncope, and was found to have transfusion-resistant pancytopenia.She had a hemolytic anemia with an LDH > 1000 U/L, haptoglobin < 3 mg/dL, and mild transaminitis with hyperbilirubinemia (1.8 mg/dL). No schistocytes were observed on peripheral smear, suggesting intramedullary hemolysis, which is believed to be due to the destruction of megaloblastic cells by macrophages in bone marrow.¹¹ A French study found high LDH levels and low reticulocyte counts to be strongly suggestive of vitamin B₁₂ deficiency and helpful in differentiating pernicious anemia from TTP, given that bone marrow response to anemia in TTP is preserved.⁸

While vitamin B₁₂ deficiency is not often associated with hemolytic anemia, multiple cases have been reported in the literature.⁶ Screening for vitamin B₁₂ deficiency may have shortened this patient’s clinical course and limited the need for air evacuation to a stateside quaternary medical center. However, testing for cobalamin levels in overseas deployed environments is difficult, timely, and costly. New technologies, such as optical sensors, can detect vitamin B₁₂ levels in the blood in < 1 minute and offer portable, low-cost options that may be useful in the deployed military setting.¹²

Diet plays a key role in this case, since the patient had a reported history of gluten intolerance, although it was never documented or evaluated prior to this presentation. Prior to deployment, the patient ate mostly rice, potatoes, and vegetables. While deployed in an austere environment, food options were limited. These conditions forced her to intermittently consume gluten products, which led to gastrointestinal issues, exacerbating her nutritional deficiencies. In the 2 months before her first syncopal episode, she reported worsening fatigue that impacted her ability to exercise. Vitamin B₁₂ stores often take years to deplete, suggesting that she had a chronic nutritional deficiency before deployment. Another possibility was that she developed an autoimmune gastritis that acutely worsened in the setting of poor nutritional intake. Her history of Hashimoto thyroiditis is also important, as up to one-third of patients with autoimmune thyroid disease have been associated with pernicious anemia (range, 3%-32%) with certain shared human leukocyte antigen alleles implicated in autoimmune gastritis.^13,14

Conclusions

This rare case of pernicious anemia presenting as pancytopenia illustrates the challenge in working up pancytopenia, especially in austere military environments with limited testing capabilities. Screening for chronic dietary and nutritional deficiency is important in a service member, raising the question of what role predeployment screening may have and what dietary accommodations may be available during overseas deployments, which can potentially dampen inflammation of the gastrointestinal tract, especially for those with preexisting autoimmune gastrointestinal conditions. Also, newer technology allows portable, low-cost testing of cobalamin and may aid in its diagnosis. In patients who are anemic with low vitamin B₁₂, HCPs can begin vitamin B₁₂ supplementation while continuing the workup (eg, antibody testing, endoscopy). If the patient responds appropriately, further workup becomes less urgent, therefore, decreasing resource use and increasing military readiness. When hemolysis is present, a low reticulocyte count can be beneficial to help differentiate this condition from TTP, a life-threatening condition that must also be ruled out or treated. Pernicious anemia should be on the differential in any patients with autoimmune conditions presenting with cytopenias, especially in those with a history of autoimmune thyroid disorders.

Pancytopenia is a condition in which all 3 hematologic cell lines are lower than expected in the blood, often representing either an increase in cellular destruction or decrease in bone marrow production. Destruction often occurs in the setting of autoimmune conditions (eg, systemic lupus erythematosus, rheumatoid arthritis) or splenic sequestration, often affecting erythrocytes and platelets more than leukocytes. Decreased production represents central etiologies, which are often due to nutritional deficiencies, infections, drug toxicities, or malabsorption.¹ Pancytopenia secondary to vitamin B₁₂ deficiency is rare, accounting for about 5% of the hematologic manifestations of symptomatic vitamin B₁₂ deficient patients.²

Pernicious anemia, named for a once lethal disease, is a form of vitamin B₁₂ (cobalamin) deficiency that results from an autoimmune (type II hypersensitivity) reaction to gastric parietal cells or intrinsic factor. Antibodies bind to gastric parietal cells and reduce gastric acid production, leading to atrophic gastritis, or they bind intrinsic factor and block the binding and absorption of vitamin B₁₂ in the gastrointestinal tract. While first described in the 1820s, it was not until a century later when scientists were studying hematopoiesis in response to the heavy casualty burden from battlefield exsanguination in World War I that dogs fed raw liver were noted to have significantly better blood regeneration response than those fed cooked liver. This discovery led physicians Minot and Murphy to use raw liver to treat pernicious anemia and found that jaundice improved, reticulocyte counts increased, and hemoglobin (Hb) concentration improved, resulting in the duo becoming the first American recipients of the Nobel Prize in physiology or medicine.³ It was ultimately determined in 1948 by chemists Folkers and Todd that the active ingredient in raw liver responsible for this phenomenon was vitamin B₁₂.⁴

Case Presentation

A 24-year-old active-duty female patient presented in late December 2020 to a theater hospital in Djibouti after a witnessed syncopal episode. She had a history of Hashimoto thyroiditis and was taking levothyroxine sodium 75 mcg daily. The patient reported gluten intolerance, which was never formally evaluated. The syncopal episode lasted a few seconds and was not associated with any prodromal or postictal symptoms. No seizure activity was observed, and she had no history of syncopal episodes. She reported that she had been feeling ill 24 to 48 hours prior, with nausea, fatigue, decreased oral intake, decreased urine output, and 2 episodes of nonbilious, nonbloody emesis.

When the patient arrived, she was tachycardic with heart rate in the 130s beats per minute (baseline, 100-110 beats per minute), febrile (103 °F), and had systolic blood pressure (SBP) in the low 100s (baseline, SBP 120s-130s). An electrocardiogram and chest radiographs were unremarkable. Her complete blood count (CBC) could not be processed due to Hb and platelet levels too low to detect on assay (Table 2). Lactate dehydrogenase (LDH) was elevated at > 1000 U/L with mild elevation in liver enzymes (aspartate aminotransferase, 98 U/L; alanine aminotransferase, 51 U/L) and prolonged partial thromboplastin time 70 seconds. She did not report any increased bleeding or bruising. The peripheral blood smear demonstrated pancytopenia, without any schistocytes, and she was started on broad-spectrum antibiotics for presumed sepsis from urinary source and possible TTP.

The patient received 5 units of packed red blood cells, transfusion of platelets, and 2 doses of vitamin B₁₂ in Djibouti with clinical improvement and resolution of orthostasis, hypotension, tachycardia, and fever. Her final posttransfusion CBC showed a Hb level of 11.2 g/dL, white blood cell (WBC) count of 1.7 K/µL, and platelet count of 23 K/µL (Table 3). Two days later her Hb level was 9.0 g/dL, WBC count 1.8 K/µL, and platelet count was 12 K/µL. She was evacuated via air to Landstuhl Regional Medical Center (LRMC) in Germany within 48 hours of presentation, given limited testing capabilities and persistent anemia and thrombocytopenia, refractory to transfusion, concerning for aplastic anemia or acute leukemia.

On arrival at LRMC, she was transfused 1 unit of platelets and given 3 doses of intramuscular vitamin B₁₂ for undetectable levels (< 50 pg/mL) at presentation. An extensive infectious workup was obtained, which did not reveal any viral, bacterial, or parasitic causes. The patient also had a bone marrow biopsy performed at a civilian site, which revealed hypocellular bone marrow. She was transferred to Walter Reed National Military Medical Center (WRNMMC) for further workup and evaluation, given the infectious workup, which was negative. Concern for hematologic malignancy remained. At the time of her arrival, the laboratory values had drastically improved with vitamin supplementation. The patient’s absolute reticulocyte count indicated adequate bone marrow response and because of her improvement, a repeat bone marrow biopsy was not performed.

Intrinsic factor antibodies were elevated (34.5 AU/mL; reference range, 0.0-1.1), which confirmed that this patient’s underlying etiology was secondary to pernicious anemia. The patient continued to improve and repeat vitamin B₁₂ and folate levels revealed that she was responding to therapy. At discharge, intramuscular vitamin B₁₂ injections were planned to continue monthly, indefinitely per guidelines. Oral supplementation is typically avoided due to poor absorption.

Of note, during her inpatient admission at WRNMMC, further evaluation of reported gluten intolerance was performed, which revealed a negative celiac disease panel (IgG/IgA tissue transglutaminase antibodies). On discharge, she was to establish care with gastroenterology for further evaluation, likely including endoscopic evaluation, at her next duty station. She was able to resume full travel and duty functions on discharge from WRNMMC.

Discussion

We highlight a complex case of pancytopenia secondary to pernicious anemia in a deployed service member. With limited resources downrange, the workup of pancytopenia can be resource intensive, expensive, and time sensitive, which can have detrimental impacts on medical readiness. Additionally, undiagnosed coagulopathies can have lethal consequences in a deployed service member where bleeding risk may be elevated depending on the mission. The differential for pancytopenia is vast, and given its relative rarity in pernicious anemia, the HCP must use key components of the history and laboratory results to narrow the differential (eAppendix).¹⁰

Pernicious anemia commonly presents as an isolated anemia. In a study looking at the hematologic manifestations of 201 cohort patients with well-documented vitamin B₁₂ deficiency, 5% had symptomatic pancytopenia and 1.5% had a hemolytic anemia.² The majority (> 67%) of hematologic abnormalities were correctable with cobalamin replacement.² In our case, the solider presented with symptomatic anemia, manifesting as syncope, and was found to have transfusion-resistant pancytopenia.She had a hemolytic anemia with an LDH > 1000 U/L, haptoglobin < 3 mg/dL, and mild transaminitis with hyperbilirubinemia (1.8 mg/dL). No schistocytes were observed on peripheral smear, suggesting intramedullary hemolysis, which is believed to be due to the destruction of megaloblastic cells by macrophages in bone marrow.¹¹ A French study found high LDH levels and low reticulocyte counts to be strongly suggestive of vitamin B₁₂ deficiency and helpful in differentiating pernicious anemia from TTP, given that bone marrow response to anemia in TTP is preserved.⁸

While vitamin B₁₂ deficiency is not often associated with hemolytic anemia, multiple cases have been reported in the literature.⁶ Screening for vitamin B₁₂ deficiency may have shortened this patient’s clinical course and limited the need for air evacuation to a stateside quaternary medical center. However, testing for cobalamin levels in overseas deployed environments is difficult, timely, and costly. New technologies, such as optical sensors, can detect vitamin B₁₂ levels in the blood in < 1 minute and offer portable, low-cost options that may be useful in the deployed military setting.¹²

Diet plays a key role in this case, since the patient had a reported history of gluten intolerance, although it was never documented or evaluated prior to this presentation. Prior to deployment, the patient ate mostly rice, potatoes, and vegetables. While deployed in an austere environment, food options were limited. These conditions forced her to intermittently consume gluten products, which led to gastrointestinal issues, exacerbating her nutritional deficiencies. In the 2 months before her first syncopal episode, she reported worsening fatigue that impacted her ability to exercise. Vitamin B₁₂ stores often take years to deplete, suggesting that she had a chronic nutritional deficiency before deployment. Another possibility was that she developed an autoimmune gastritis that acutely worsened in the setting of poor nutritional intake. Her history of Hashimoto thyroiditis is also important, as up to one-third of patients with autoimmune thyroid disease have been associated with pernicious anemia (range, 3%-32%) with certain shared human leukocyte antigen alleles implicated in autoimmune gastritis.^13,14

Conclusions

This rare case of pernicious anemia presenting as pancytopenia illustrates the challenge in working up pancytopenia, especially in austere military environments with limited testing capabilities. Screening for chronic dietary and nutritional deficiency is important in a service member, raising the question of what role predeployment screening may have and what dietary accommodations may be available during overseas deployments, which can potentially dampen inflammation of the gastrointestinal tract, especially for those with preexisting autoimmune gastrointestinal conditions. Also, newer technology allows portable, low-cost testing of cobalamin and may aid in its diagnosis. In patients who are anemic with low vitamin B₁₂, HCPs can begin vitamin B₁₂ supplementation while continuing the workup (eg, antibody testing, endoscopy). If the patient responds appropriately, further workup becomes less urgent, therefore, decreasing resource use and increasing military readiness. When hemolysis is present, a low reticulocyte count can be beneficial to help differentiate this condition from TTP, a life-threatening condition that must also be ruled out or treated. Pernicious anemia should be on the differential in any patients with autoimmune conditions presenting with cytopenias, especially in those with a history of autoimmune thyroid disorders.

As a class of drugs, proteasome inhibitors are known to rarely cause drug-induced thrombotic microangiopathy (DITMA). In particular, carfilzomib is a second-generation, irreversible proteasome inhibitor approved for the treatment of relapsed, refractory multiple myeloma (MM) in combination with other therapeutic agents.¹ Although generally well tolerated, carfilzomib has been associated with serious adverse events such as cardiovascular toxicity and DITMA.^2-4 Thrombotic microangiopathy (TMA) is a life-threatening disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, and end-organ damage.⁵ Its occurrence secondary to carfilzomib has been reported only rarely in clinical trials of MM, and the most effective management of the disorder as well as the concurrent risk factors that contribute to its development remain incompletely understood.^6,7 As a result, given both the expanding use of carfilzomib in practice and the morbidity of TMA, descriptions of carfilzomib-induced TMA from the real-world setting continue to provide important contributions to our understanding of the disorder.

At our US Department of Veterans Affairs (VA) medical center, 2 patients developed severe carfilzomib-induced TMA within days of one another. The presentation of simultaneous cases was highly unexpected and offered the unique opportunity to compare clinical features in real time. Here, we describe our 2 cases in detail, review their presentations and management in the context of the prior literature, and discuss potential insights gained into the disease.

Case Presentation

Case 1

A 78-year-old male patient was diagnosed with monoclonal gammopathy of undetermined significance in 2012 that progressed to Revised International Staging System stage II IgG-κ MM in 2016 due to worsening anemia with a hemoglobin level < 10 g/dL (Table 1). He was treated initially with 8 cycles of first-line bortezomib, lenalidomide, and dexamethasone, to which he achieved a partial response with > 50% reduction in serum M-protein. He then received 3 cycles of maintenance bortezomib until relapse, at which time he was switched to second-line therapy consisting of carfilzomib 20 mg/m² on days 1 and 2 and 56 mg/m² on days 8, 9, 15, and 16 for cycle 1, followed by 56 mg/m² on days 1, 2, 8, 9, 15, and 16 for subsequent cycles plus dexamethasone 20 mg twice weekly every 28 days.

After the patient received cycle 3, day 1 of carfilzomib, he developed subjective fevers, chills, and diarrhea. He missed his day 2 infusion and instead presented to the VA emergency department, where his vital signs were stable and laboratory tests were notable for the following levels: leukocytosis of20.3 K/µL (91.7% neutrophils), hemoglobin 12.4 g/dL (prior 13.5 g/dL), platelet count 171 K/µL, and creatinine 1.39 mg/dL (prior 1.13 g/dL). A chest X-ray demonstrated diffuse bilateral opacities concerning for edema vs infection, and he was started empirically on vancomycin, piperacillin-tazobactam, and azithromycin. His outpatient medications, which included acyclovir, aspirin, finasteride, oxybutynin, ranitidine, omega-3 fatty acids, fish oil, vitamin D, and senna, were continued as indicated.

On hospital day 2, the patient’s platelet count dropped to 81 K/µL and creatinine level rose to 1.78 mg/dL. He developed dark urine (urinalysis [UA] 3+ blood, 6-11 red blood cells per high power field [RBC/HPF]) and had laboratory tests suggestive of hemolysis, including lactic dehydrogenase (LDH) > 1,200 IU/L (reference range, 60-250 IU/L), haptoglobin < 30 mg/dL (reference range, 44-215 mg/dL), total bilirubin 3.2 mg/dL (reference range, 0.2-1.3 mg/dL; indirect bilirubin, 2.6 mg/dL), and a peripheral blood smear demonstrating moderate microangiopathy (Figure 1).

Case 2

A 59-year-old male patient, diagnosed in 2013 with ISS stage I IgG-κ MM after presenting with compression fractures, completed 8 cycles of cyclophosphamide, bortezomib, and dexamethasone before undergoing autologous hematopoietic stem cell transplantation with complete response (Table 1). He subsequently received single-agent maintenance bortezomib until relapse nearly 2 years later, at which time he started second-line carfilzomib 20 mg/m² on days 1 and 2 and 27 mg/m² on days 8, 9, 15, and 16 for cycle 1, followed by 27 mg/m² on days 8, 9, 15, and 16 for cycles 2 to 8, lenalidomide 25 mg on days 1 to 21, and dexamethasone 40 mg weekly every 28 days. Serum free light chain levels normalized after 9 cycles, and he subsequently began maintenance carfilzomib 70 mg/m² on days 1 and 15 plus lenalidomide 10 mg on days 1 to 21 every 28 days.

On the morning before admission, the patient received C6D17 of maintenance carfilzomib, which had been delayed from day 15 because of the holiday. Later that evening, he developed nausea, vomiting, and fever of 101.3 °F. He presented to the VA emergency department and was tachycardic (108 beats per minute) and hypotensive (86/55 mm Hg). Laboratory tests were notable for hemoglobin level 9.9 g/dL (prior 11.6 g/dL), platelet count 270 K/µL, and creatinine level 1.86 mg/dL (prior 1.12 mg/dL). A respiratory viral panel was positive for influenza A, and antimicrobial agents were eventually broadened to piperacillin-tazobactam, azithromycin, and oseltamivir. His outpatient medications, which included acyclovir, zoledronic acid, sulfamethoxazole/trimethoprim, aspirin, amlodipine, atorvastatin, omeprazole, zolpidem, calcium, vitamin D, loratadine, ascorbic acid, and prochlorperazine, were continued as indicated.

On hospital day 2, the patient’s platelet count declined from 211 to 57 K/µL. He developed tea-colored urine (UA 2+ blood, 0-2 RBC/HPF) and had laboratory tests suggestive of hemolysis, including LDH 910 IU/L (reference range, 60-250 IU/L), total bilirubin 3.3 mg/dL (reference range, 0.2-1.3 mg/dL; no direct or indirect available), and a peripheral blood smear demonstrating moderate microangiopathy. Although haptoglobin level was normal at this time (206 mg/dL; reference range, 44-215 mg/dL), it decreased to 42 mg/dL by the following day. Additional workup included a negative direct Coombs and a DIC panel showing elevated fibrinogen (596 mg/dL; reference range, 200-400 mg/dL) and mildly elevated INR (1.16). Blood cultures remained negative, and a 22-pathogen GI PCR panel identified no viral or bacterial pathogens, including E coli O157:H7. C3 (114 mg/dL; reference range, 90-180 mg/dL) and C4 (40 mg/dL; reference range, 16-47 mg/dL) complement levels were both normal.

Based on these findings, empiric treatment was started with plasma exchange and pulse-dosed steroids. The patient received 3 cycles of plasma exchange until the results of the ADAMTS13 activity ruled out TTP (63% enzyme activity). Over the next 6 days, his platelet count reached a nadir of 6 K/µL and creatinine level peaked at 10.36 mg/dL, necessitating the initiation of hemodialysis. Given severe renal insufficiency, a diagnosis of atypical HUS was again considered, and eculizumab 900 mg was administered on days 9 and 16 with stabilization of renal function. By the time of discharge on day 17, the patient’s creatinine level had decreased to 4.17 mg/dL and platelet count was 164 K/µL. Creatinine level normalized to 1.02 mg/dL by day 72.

Outpatient genetic testing through the BloodCenter of Wisconsin Diagnostic Laboratories was negative for gene mutations associated with atypical HUS. Approximately 1 month after discharge, the patient resumed maintenance lenalidomide alone without reinitiation of proteasome inhibitor therapy.

Discussion

In this case series, we describe the uncommon drug-related adverse event of TMA occurring in 2 patients with MM after receiving carfilzomib. Although the incidence of TMA disorders is low, reaching up to 2.8% in patients receiving carfilzomib plus cyclophosphamide and dexamethasone in the phase 2 CARDAMON trial, our experience suggests that a high index of suspicion for carfilzomib-induced TMA is warranted in the real-world setting.⁸ TMA syndromes, including TTP, HUS, and DITMA, are characterized by microvascular endothelial injury and thrombosis leading to thrombocytopenia and microangiopathic hemolytic anemia.^5,9 Several drug culprits of DITMA are recognized, including quinine, gemcitabine, tacrolimus, and proteasome inhibitors (bortezomib, carfilzomib, ixazomib).^10-12 In a real-world series of patients receiving proteasome inhibitor therapy, either carfilzomib (n=8) or bortezomib (n=3), common clinical features of DITMA included thrombocytopenia, microangiopathic hemolytic anemia, gastrointestinal symptoms, and renal insufficiency with or without a need for hemodialysis.² Although DITMA has been described primarily as an early event, its occurrence after 12 months of proteasome inhibitor therapy has also been reported, both in this series and elsewhere, thereby suggesting an ongoing risk for DITMA throughout the duration of carfilzomib treatment.^2,13

The diagnosis of DITMA can be challenging given its nonspecific symptoms that overlap with other TMA syndromes. Previous studies have proposed that for a drug to be associated with DITMA, there should be: (1) evidence of clinical and/or pathologic findings of TMA; (2) exclusion of alternative causes of TMA; (3) no other new drug exposures other than the suspected culprit medication; and (4) a lack of recurrence of TMA in absence of the drug.¹⁰ In the case of patients with MM, other causes of TMA have also been described, including the underlying plasma cell disorder itself and stem cell transplantation.¹⁴ In the 2 cases we have described, these alternative causes were considered unlikely given that only 1 patient underwent transplantation remotely and neither had a previous history of TMA secondary to their disease. With respect to other TMA syndromes, ADAMTS13 levels > 10% and negative stool studies for E coli O157:H7 suggested against TTP or typical HUS, respectively. No other drug culprits were identified, and the close timing between the receipt of carfilzomib and symptom onset supported a causal relationship.

Because specific therapies are lacking, management of DITMA has traditionally included drug discontinuation and supportive care for end-organ injury.⁵ The terminal complement inhibitor, eculizumab, improves hematologic abnormalities and renal function in patients with atypical HUS but its use for treating patients with DITMA is not standard.¹⁵ Therefore, the decision to administer eculizumab to our 2 patients was driven by their severe renal insufficiency without improvement after plasma exchange, which suggested a phenotype similar to atypical HUS. After administration of eculizumab, renal function stabilized and then gradually improved over weeks to months, a time course similar to that described in cases of patients with DITMA secondary to other anticancer therapies treated with eculizumab.¹⁶ Although these results suggest a potential role for eculizumab in proteasome inhibitor–induced TMA, distinguishing the benefit of eculizumab over drug discontinuation alone remains challenging, and well-designed prospective investigations are needed.

Conclusions

DITMA is a known risk of proteasome inhibitors and is listed as a safety warning in the prescribing information for bortezomib, carfilzomib, and ixazomib.¹² Given the overall rarity of this adverse event, the simultaneous presentation of our 2 cases was unexpected and underscores the need for heightened awareness in clinical practice. In addition, while no underlying complement mutations were identified, eculizumab was used in both cases to successfully stabilize renal function. Further research investigating the efficacy of eculizumab and the role of complement activation in proteasome inhibitor–induced TMA will be valuable.

Acknowledgments

The authors would like to thank the patients whose histories are reported in this manuscript as well as the physicians and staff who provided care during the hospitalizations and beyond. We also thank Oscar Silva, MD, PhD, for his assistance in reviewing and formatting the peripheral blood smear images.

As a class of drugs, proteasome inhibitors are known to rarely cause drug-induced thrombotic microangiopathy (DITMA). In particular, carfilzomib is a second-generation, irreversible proteasome inhibitor approved for the treatment of relapsed, refractory multiple myeloma (MM) in combination with other therapeutic agents.¹ Although generally well tolerated, carfilzomib has been associated with serious adverse events such as cardiovascular toxicity and DITMA.^2-4 Thrombotic microangiopathy (TMA) is a life-threatening disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, and end-organ damage.⁵ Its occurrence secondary to carfilzomib has been reported only rarely in clinical trials of MM, and the most effective management of the disorder as well as the concurrent risk factors that contribute to its development remain incompletely understood.^6,7 As a result, given both the expanding use of carfilzomib in practice and the morbidity of TMA, descriptions of carfilzomib-induced TMA from the real-world setting continue to provide important contributions to our understanding of the disorder.

At our US Department of Veterans Affairs (VA) medical center, 2 patients developed severe carfilzomib-induced TMA within days of one another. The presentation of simultaneous cases was highly unexpected and offered the unique opportunity to compare clinical features in real time. Here, we describe our 2 cases in detail, review their presentations and management in the context of the prior literature, and discuss potential insights gained into the disease.

Case Presentation

Case 1

A 78-year-old male patient was diagnosed with monoclonal gammopathy of undetermined significance in 2012 that progressed to Revised International Staging System stage II IgG-κ MM in 2016 due to worsening anemia with a hemoglobin level < 10 g/dL (Table 1). He was treated initially with 8 cycles of first-line bortezomib, lenalidomide, and dexamethasone, to which he achieved a partial response with > 50% reduction in serum M-protein. He then received 3 cycles of maintenance bortezomib until relapse, at which time he was switched to second-line therapy consisting of carfilzomib 20 mg/m² on days 1 and 2 and 56 mg/m² on days 8, 9, 15, and 16 for cycle 1, followed by 56 mg/m² on days 1, 2, 8, 9, 15, and 16 for subsequent cycles plus dexamethasone 20 mg twice weekly every 28 days.

After the patient received cycle 3, day 1 of carfilzomib, he developed subjective fevers, chills, and diarrhea. He missed his day 2 infusion and instead presented to the VA emergency department, where his vital signs were stable and laboratory tests were notable for the following levels: leukocytosis of20.3 K/µL (91.7% neutrophils), hemoglobin 12.4 g/dL (prior 13.5 g/dL), platelet count 171 K/µL, and creatinine 1.39 mg/dL (prior 1.13 g/dL). A chest X-ray demonstrated diffuse bilateral opacities concerning for edema vs infection, and he was started empirically on vancomycin, piperacillin-tazobactam, and azithromycin. His outpatient medications, which included acyclovir, aspirin, finasteride, oxybutynin, ranitidine, omega-3 fatty acids, fish oil, vitamin D, and senna, were continued as indicated.

On hospital day 2, the patient’s platelet count dropped to 81 K/µL and creatinine level rose to 1.78 mg/dL. He developed dark urine (urinalysis [UA] 3+ blood, 6-11 red blood cells per high power field [RBC/HPF]) and had laboratory tests suggestive of hemolysis, including lactic dehydrogenase (LDH) > 1,200 IU/L (reference range, 60-250 IU/L), haptoglobin < 30 mg/dL (reference range, 44-215 mg/dL), total bilirubin 3.2 mg/dL (reference range, 0.2-1.3 mg/dL; indirect bilirubin, 2.6 mg/dL), and a peripheral blood smear demonstrating moderate microangiopathy (Figure 1).

Case 2

A 59-year-old male patient, diagnosed in 2013 with ISS stage I IgG-κ MM after presenting with compression fractures, completed 8 cycles of cyclophosphamide, bortezomib, and dexamethasone before undergoing autologous hematopoietic stem cell transplantation with complete response (Table 1). He subsequently received single-agent maintenance bortezomib until relapse nearly 2 years later, at which time he started second-line carfilzomib 20 mg/m² on days 1 and 2 and 27 mg/m² on days 8, 9, 15, and 16 for cycle 1, followed by 27 mg/m² on days 8, 9, 15, and 16 for cycles 2 to 8, lenalidomide 25 mg on days 1 to 21, and dexamethasone 40 mg weekly every 28 days. Serum free light chain levels normalized after 9 cycles, and he subsequently began maintenance carfilzomib 70 mg/m² on days 1 and 15 plus lenalidomide 10 mg on days 1 to 21 every 28 days.

On the morning before admission, the patient received C6D17 of maintenance carfilzomib, which had been delayed from day 15 because of the holiday. Later that evening, he developed nausea, vomiting, and fever of 101.3 °F. He presented to the VA emergency department and was tachycardic (108 beats per minute) and hypotensive (86/55 mm Hg). Laboratory tests were notable for hemoglobin level 9.9 g/dL (prior 11.6 g/dL), platelet count 270 K/µL, and creatinine level 1.86 mg/dL (prior 1.12 mg/dL). A respiratory viral panel was positive for influenza A, and antimicrobial agents were eventually broadened to piperacillin-tazobactam, azithromycin, and oseltamivir. His outpatient medications, which included acyclovir, zoledronic acid, sulfamethoxazole/trimethoprim, aspirin, amlodipine, atorvastatin, omeprazole, zolpidem, calcium, vitamin D, loratadine, ascorbic acid, and prochlorperazine, were continued as indicated.

On hospital day 2, the patient’s platelet count declined from 211 to 57 K/µL. He developed tea-colored urine (UA 2+ blood, 0-2 RBC/HPF) and had laboratory tests suggestive of hemolysis, including LDH 910 IU/L (reference range, 60-250 IU/L), total bilirubin 3.3 mg/dL (reference range, 0.2-1.3 mg/dL; no direct or indirect available), and a peripheral blood smear demonstrating moderate microangiopathy. Although haptoglobin level was normal at this time (206 mg/dL; reference range, 44-215 mg/dL), it decreased to 42 mg/dL by the following day. Additional workup included a negative direct Coombs and a DIC panel showing elevated fibrinogen (596 mg/dL; reference range, 200-400 mg/dL) and mildly elevated INR (1.16). Blood cultures remained negative, and a 22-pathogen GI PCR panel identified no viral or bacterial pathogens, including E coli O157:H7. C3 (114 mg/dL; reference range, 90-180 mg/dL) and C4 (40 mg/dL; reference range, 16-47 mg/dL) complement levels were both normal.

Based on these findings, empiric treatment was started with plasma exchange and pulse-dosed steroids. The patient received 3 cycles of plasma exchange until the results of the ADAMTS13 activity ruled out TTP (63% enzyme activity). Over the next 6 days, his platelet count reached a nadir of 6 K/µL and creatinine level peaked at 10.36 mg/dL, necessitating the initiation of hemodialysis. Given severe renal insufficiency, a diagnosis of atypical HUS was again considered, and eculizumab 900 mg was administered on days 9 and 16 with stabilization of renal function. By the time of discharge on day 17, the patient’s creatinine level had decreased to 4.17 mg/dL and platelet count was 164 K/µL. Creatinine level normalized to 1.02 mg/dL by day 72.

Outpatient genetic testing through the BloodCenter of Wisconsin Diagnostic Laboratories was negative for gene mutations associated with atypical HUS. Approximately 1 month after discharge, the patient resumed maintenance lenalidomide alone without reinitiation of proteasome inhibitor therapy.

Discussion

In this case series, we describe the uncommon drug-related adverse event of TMA occurring in 2 patients with MM after receiving carfilzomib. Although the incidence of TMA disorders is low, reaching up to 2.8% in patients receiving carfilzomib plus cyclophosphamide and dexamethasone in the phase 2 CARDAMON trial, our experience suggests that a high index of suspicion for carfilzomib-induced TMA is warranted in the real-world setting.⁸ TMA syndromes, including TTP, HUS, and DITMA, are characterized by microvascular endothelial injury and thrombosis leading to thrombocytopenia and microangiopathic hemolytic anemia.^5,9 Several drug culprits of DITMA are recognized, including quinine, gemcitabine, tacrolimus, and proteasome inhibitors (bortezomib, carfilzomib, ixazomib).^10-12 In a real-world series of patients receiving proteasome inhibitor therapy, either carfilzomib (n=8) or bortezomib (n=3), common clinical features of DITMA included thrombocytopenia, microangiopathic hemolytic anemia, gastrointestinal symptoms, and renal insufficiency with or without a need for hemodialysis.² Although DITMA has been described primarily as an early event, its occurrence after 12 months of proteasome inhibitor therapy has also been reported, both in this series and elsewhere, thereby suggesting an ongoing risk for DITMA throughout the duration of carfilzomib treatment.^2,13

The diagnosis of DITMA can be challenging given its nonspecific symptoms that overlap with other TMA syndromes. Previous studies have proposed that for a drug to be associated with DITMA, there should be: (1) evidence of clinical and/or pathologic findings of TMA; (2) exclusion of alternative causes of TMA; (3) no other new drug exposures other than the suspected culprit medication; and (4) a lack of recurrence of TMA in absence of the drug.¹⁰ In the case of patients with MM, other causes of TMA have also been described, including the underlying plasma cell disorder itself and stem cell transplantation.¹⁴ In the 2 cases we have described, these alternative causes were considered unlikely given that only 1 patient underwent transplantation remotely and neither had a previous history of TMA secondary to their disease. With respect to other TMA syndromes, ADAMTS13 levels > 10% and negative stool studies for E coli O157:H7 suggested against TTP or typical HUS, respectively. No other drug culprits were identified, and the close timing between the receipt of carfilzomib and symptom onset supported a causal relationship.

Because specific therapies are lacking, management of DITMA has traditionally included drug discontinuation and supportive care for end-organ injury.⁵ The terminal complement inhibitor, eculizumab, improves hematologic abnormalities and renal function in patients with atypical HUS but its use for treating patients with DITMA is not standard.¹⁵ Therefore, the decision to administer eculizumab to our 2 patients was driven by their severe renal insufficiency without improvement after plasma exchange, which suggested a phenotype similar to atypical HUS. After administration of eculizumab, renal function stabilized and then gradually improved over weeks to months, a time course similar to that described in cases of patients with DITMA secondary to other anticancer therapies treated with eculizumab.¹⁶ Although these results suggest a potential role for eculizumab in proteasome inhibitor–induced TMA, distinguishing the benefit of eculizumab over drug discontinuation alone remains challenging, and well-designed prospective investigations are needed.

Conclusions

DITMA is a known risk of proteasome inhibitors and is listed as a safety warning in the prescribing information for bortezomib, carfilzomib, and ixazomib.¹² Given the overall rarity of this adverse event, the simultaneous presentation of our 2 cases was unexpected and underscores the need for heightened awareness in clinical practice. In addition, while no underlying complement mutations were identified, eculizumab was used in both cases to successfully stabilize renal function. Further research investigating the efficacy of eculizumab and the role of complement activation in proteasome inhibitor–induced TMA will be valuable.

Acknowledgments

The authors would like to thank the patients whose histories are reported in this manuscript as well as the physicians and staff who provided care during the hospitalizations and beyond. We also thank Oscar Silva, MD, PhD, for his assistance in reviewing and formatting the peripheral blood smear images.

As a class of drugs, proteasome inhibitors are known to rarely cause drug-induced thrombotic microangiopathy (DITMA). In particular, carfilzomib is a second-generation, irreversible proteasome inhibitor approved for the treatment of relapsed, refractory multiple myeloma (MM) in combination with other therapeutic agents.¹ Although generally well tolerated, carfilzomib has been associated with serious adverse events such as cardiovascular toxicity and DITMA.^2-4 Thrombotic microangiopathy (TMA) is a life-threatening disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, and end-organ damage.⁵ Its occurrence secondary to carfilzomib has been reported only rarely in clinical trials of MM, and the most effective management of the disorder as well as the concurrent risk factors that contribute to its development remain incompletely understood.^6,7 As a result, given both the expanding use of carfilzomib in practice and the morbidity of TMA, descriptions of carfilzomib-induced TMA from the real-world setting continue to provide important contributions to our understanding of the disorder.

At our US Department of Veterans Affairs (VA) medical center, 2 patients developed severe carfilzomib-induced TMA within days of one another. The presentation of simultaneous cases was highly unexpected and offered the unique opportunity to compare clinical features in real time. Here, we describe our 2 cases in detail, review their presentations and management in the context of the prior literature, and discuss potential insights gained into the disease.

Case Presentation

Case 1

A 78-year-old male patient was diagnosed with monoclonal gammopathy of undetermined significance in 2012 that progressed to Revised International Staging System stage II IgG-κ MM in 2016 due to worsening anemia with a hemoglobin level < 10 g/dL (Table 1). He was treated initially with 8 cycles of first-line bortezomib, lenalidomide, and dexamethasone, to which he achieved a partial response with > 50% reduction in serum M-protein. He then received 3 cycles of maintenance bortezomib until relapse, at which time he was switched to second-line therapy consisting of carfilzomib 20 mg/m² on days 1 and 2 and 56 mg/m² on days 8, 9, 15, and 16 for cycle 1, followed by 56 mg/m² on days 1, 2, 8, 9, 15, and 16 for subsequent cycles plus dexamethasone 20 mg twice weekly every 28 days.

After the patient received cycle 3, day 1 of carfilzomib, he developed subjective fevers, chills, and diarrhea. He missed his day 2 infusion and instead presented to the VA emergency department, where his vital signs were stable and laboratory tests were notable for the following levels: leukocytosis of20.3 K/µL (91.7% neutrophils), hemoglobin 12.4 g/dL (prior 13.5 g/dL), platelet count 171 K/µL, and creatinine 1.39 mg/dL (prior 1.13 g/dL). A chest X-ray demonstrated diffuse bilateral opacities concerning for edema vs infection, and he was started empirically on vancomycin, piperacillin-tazobactam, and azithromycin. His outpatient medications, which included acyclovir, aspirin, finasteride, oxybutynin, ranitidine, omega-3 fatty acids, fish oil, vitamin D, and senna, were continued as indicated.

On hospital day 2, the patient’s platelet count dropped to 81 K/µL and creatinine level rose to 1.78 mg/dL. He developed dark urine (urinalysis [UA] 3+ blood, 6-11 red blood cells per high power field [RBC/HPF]) and had laboratory tests suggestive of hemolysis, including lactic dehydrogenase (LDH) > 1,200 IU/L (reference range, 60-250 IU/L), haptoglobin < 30 mg/dL (reference range, 44-215 mg/dL), total bilirubin 3.2 mg/dL (reference range, 0.2-1.3 mg/dL; indirect bilirubin, 2.6 mg/dL), and a peripheral blood smear demonstrating moderate microangiopathy (Figure 1).

Case 2

A 59-year-old male patient, diagnosed in 2013 with ISS stage I IgG-κ MM after presenting with compression fractures, completed 8 cycles of cyclophosphamide, bortezomib, and dexamethasone before undergoing autologous hematopoietic stem cell transplantation with complete response (Table 1). He subsequently received single-agent maintenance bortezomib until relapse nearly 2 years later, at which time he started second-line carfilzomib 20 mg/m² on days 1 and 2 and 27 mg/m² on days 8, 9, 15, and 16 for cycle 1, followed by 27 mg/m² on days 8, 9, 15, and 16 for cycles 2 to 8, lenalidomide 25 mg on days 1 to 21, and dexamethasone 40 mg weekly every 28 days. Serum free light chain levels normalized after 9 cycles, and he subsequently began maintenance carfilzomib 70 mg/m² on days 1 and 15 plus lenalidomide 10 mg on days 1 to 21 every 28 days.

On the morning before admission, the patient received C6D17 of maintenance carfilzomib, which had been delayed from day 15 because of the holiday. Later that evening, he developed nausea, vomiting, and fever of 101.3 °F. He presented to the VA emergency department and was tachycardic (108 beats per minute) and hypotensive (86/55 mm Hg). Laboratory tests were notable for hemoglobin level 9.9 g/dL (prior 11.6 g/dL), platelet count 270 K/µL, and creatinine level 1.86 mg/dL (prior 1.12 mg/dL). A respiratory viral panel was positive for influenza A, and antimicrobial agents were eventually broadened to piperacillin-tazobactam, azithromycin, and oseltamivir. His outpatient medications, which included acyclovir, zoledronic acid, sulfamethoxazole/trimethoprim, aspirin, amlodipine, atorvastatin, omeprazole, zolpidem, calcium, vitamin D, loratadine, ascorbic acid, and prochlorperazine, were continued as indicated.

On hospital day 2, the patient’s platelet count declined from 211 to 57 K/µL. He developed tea-colored urine (UA 2+ blood, 0-2 RBC/HPF) and had laboratory tests suggestive of hemolysis, including LDH 910 IU/L (reference range, 60-250 IU/L), total bilirubin 3.3 mg/dL (reference range, 0.2-1.3 mg/dL; no direct or indirect available), and a peripheral blood smear demonstrating moderate microangiopathy. Although haptoglobin level was normal at this time (206 mg/dL; reference range, 44-215 mg/dL), it decreased to 42 mg/dL by the following day. Additional workup included a negative direct Coombs and a DIC panel showing elevated fibrinogen (596 mg/dL; reference range, 200-400 mg/dL) and mildly elevated INR (1.16). Blood cultures remained negative, and a 22-pathogen GI PCR panel identified no viral or bacterial pathogens, including E coli O157:H7. C3 (114 mg/dL; reference range, 90-180 mg/dL) and C4 (40 mg/dL; reference range, 16-47 mg/dL) complement levels were both normal.

Based on these findings, empiric treatment was started with plasma exchange and pulse-dosed steroids. The patient received 3 cycles of plasma exchange until the results of the ADAMTS13 activity ruled out TTP (63% enzyme activity). Over the next 6 days, his platelet count reached a nadir of 6 K/µL and creatinine level peaked at 10.36 mg/dL, necessitating the initiation of hemodialysis. Given severe renal insufficiency, a diagnosis of atypical HUS was again considered, and eculizumab 900 mg was administered on days 9 and 16 with stabilization of renal function. By the time of discharge on day 17, the patient’s creatinine level had decreased to 4.17 mg/dL and platelet count was 164 K/µL. Creatinine level normalized to 1.02 mg/dL by day 72.

Outpatient genetic testing through the BloodCenter of Wisconsin Diagnostic Laboratories was negative for gene mutations associated with atypical HUS. Approximately 1 month after discharge, the patient resumed maintenance lenalidomide alone without reinitiation of proteasome inhibitor therapy.

Discussion

In this case series, we describe the uncommon drug-related adverse event of TMA occurring in 2 patients with MM after receiving carfilzomib. Although the incidence of TMA disorders is low, reaching up to 2.8% in patients receiving carfilzomib plus cyclophosphamide and dexamethasone in the phase 2 CARDAMON trial, our experience suggests that a high index of suspicion for carfilzomib-induced TMA is warranted in the real-world setting.⁸ TMA syndromes, including TTP, HUS, and DITMA, are characterized by microvascular endothelial injury and thrombosis leading to thrombocytopenia and microangiopathic hemolytic anemia.^5,9 Several drug culprits of DITMA are recognized, including quinine, gemcitabine, tacrolimus, and proteasome inhibitors (bortezomib, carfilzomib, ixazomib).^10-12 In a real-world series of patients receiving proteasome inhibitor therapy, either carfilzomib (n=8) or bortezomib (n=3), common clinical features of DITMA included thrombocytopenia, microangiopathic hemolytic anemia, gastrointestinal symptoms, and renal insufficiency with or without a need for hemodialysis.² Although DITMA has been described primarily as an early event, its occurrence after 12 months of proteasome inhibitor therapy has also been reported, both in this series and elsewhere, thereby suggesting an ongoing risk for DITMA throughout the duration of carfilzomib treatment.^2,13

The diagnosis of DITMA can be challenging given its nonspecific symptoms that overlap with other TMA syndromes. Previous studies have proposed that for a drug to be associated with DITMA, there should be: (1) evidence of clinical and/or pathologic findings of TMA; (2) exclusion of alternative causes of TMA; (3) no other new drug exposures other than the suspected culprit medication; and (4) a lack of recurrence of TMA in absence of the drug.¹⁰ In the case of patients with MM, other causes of TMA have also been described, including the underlying plasma cell disorder itself and stem cell transplantation.¹⁴ In the 2 cases we have described, these alternative causes were considered unlikely given that only 1 patient underwent transplantation remotely and neither had a previous history of TMA secondary to their disease. With respect to other TMA syndromes, ADAMTS13 levels > 10% and negative stool studies for E coli O157:H7 suggested against TTP or typical HUS, respectively. No other drug culprits were identified, and the close timing between the receipt of carfilzomib and symptom onset supported a causal relationship.

Because specific therapies are lacking, management of DITMA has traditionally included drug discontinuation and supportive care for end-organ injury.⁵ The terminal complement inhibitor, eculizumab, improves hematologic abnormalities and renal function in patients with atypical HUS but its use for treating patients with DITMA is not standard.¹⁵ Therefore, the decision to administer eculizumab to our 2 patients was driven by their severe renal insufficiency without improvement after plasma exchange, which suggested a phenotype similar to atypical HUS. After administration of eculizumab, renal function stabilized and then gradually improved over weeks to months, a time course similar to that described in cases of patients with DITMA secondary to other anticancer therapies treated with eculizumab.¹⁶ Although these results suggest a potential role for eculizumab in proteasome inhibitor–induced TMA, distinguishing the benefit of eculizumab over drug discontinuation alone remains challenging, and well-designed prospective investigations are needed.

Conclusions

DITMA is a known risk of proteasome inhibitors and is listed as a safety warning in the prescribing information for bortezomib, carfilzomib, and ixazomib.¹² Given the overall rarity of this adverse event, the simultaneous presentation of our 2 cases was unexpected and underscores the need for heightened awareness in clinical practice. In addition, while no underlying complement mutations were identified, eculizumab was used in both cases to successfully stabilize renal function. Further research investigating the efficacy of eculizumab and the role of complement activation in proteasome inhibitor–induced TMA will be valuable.

Acknowledgments

The authors would like to thank the patients whose histories are reported in this manuscript as well as the physicians and staff who provided care during the hospitalizations and beyond. We also thank Oscar Silva, MD, PhD, for his assistance in reviewing and formatting the peripheral blood smear images.

Rheumatologic conditions and infections may imitate each other, often making diagnosis challenging. Therefore, it is imperative to obtain adequate histories and have a keen eye for these potentially confounding differential diagnoses. Immunosuppressants used in managing rheumatologic etiologies have detrimental consequences in undiagnosed underlying infections. Consequently, worsening symptoms with standard therapy should raise awareness to a different diagnosis.

Nontuberculous mycobacteria (NTM) are slow-growing organisms difficult to yield in culture. Initial negative synovial fluid stains and cultures when suspecting NTM infectious arthritis or tenosynovitis should not exclude the diagnosis if there is a strong clinical scenario. The identification of Mycobacterium marinum (M marinum) infection in the hand is of utmost importance given that delayed treatment may cause significant and even permanent disability.

We present the case of a 73-year-old male patient with progressively worsening right-hand tenosynovitis who was evaluated for crystal-induced and sarcoid arthropathies in the setting of negative synovial biopsy cultures but was subsequently diagnosed with M marinum infectious tenosynovitis after a second surgical debridement.

Case Presentation

A 73-year-old male patient with history of type 2 diabetes mellitus, hypertension, hyperlipidemia, hypothyroidism, bilateral knee osteoarthritis, obstructive sleep apnea, and posttraumatic stress disorder presented to the emergency department (ED) with right wrist swelling and pain for 4 days. The patient reported that he was working in his garden when symptoms started. He did not recall any skin abrasions or wounds, insect bites, thorn punctures, trauma, or exposure to swimming pools or fish tanks. Patient was afebrile, and vital signs were within normal range. On physical examination, there was erythema, swelling, and tenderness in the dorsum of the right hand and over the dorsal aspect of the fourth metacarpophalangeal joint (Figure 1). The skin was intact.

Symptoms had not responded to 7 days of cefalexin nor to a short course of oral steroids. Leukocytosis of 14.35 × 10⁹/L (reference range, 3.90-9.90 × 10⁹/L) with neutrophilia at 11.10 × 10^9/L (reference range, 1.73-6.37 × 10⁹/L) was noted. Sedimentation rate and C-reactive protein levels were normal. Right-hand X-ray was remarkable for chondrocalcinosis in the triangular fibrocartilage. Right upper extremity magnetic resonance imaging (MRI) revealed diffuse inflammation in the right wrist and hand (Figure 2). There was no evidence of septic arthritis or osteomyelitis. Consequently, orthopedic service recommended no surgical intervention. Additionally, the patient had preserved range of motion that further indicated tenosynovitis, which could be medically managed with antibiotics, rather than a septic joint.

One dose of IV piperacillin/tazobactam was given at the ED, and he was admitted to the internal medicine ward with right hand and wrist cellulitis and indolent suppurative tenosynovitis. Empiric IV ceftriaxone and vancomycin were started as per infectious disease (ID) service with adequate response defined as a reduction of the swelling, erythema, and tenderness of the right hand and wrist. Differential diagnosis included sporotrichosis, nocardia vs NTM infection.

Interventional radiology was consulted for right wrist drainage. However, only 1 mL of fluid was obtained. Synovial fluid was sent for cell count and differential, crystal analysis, bacterial cultures, fungal cultures, and acid-fast bacilli (AFB) stains and culture. Neutrophils were 43% and lymphocytes were 57%. Crystal analysis was negative. Bacterial culture and mycology were negative. AFB stain and culture results were negative after 6 weeks. Based on gardening history and risk of thorn exposure and low suspicion for common bacterial pathogens, ID service switched antibiotics to moxifloxacin, minocycline, and linezolid for broad coverage to complete 3 weeks as outpatient. The patient reported significantly improved pain and handgrip with notable decrease in swelling. Nonetheless, 3 weeks after completing antibiotics, the right-hand pain recurred, raising concern for complex regional syndrome vs crystalline arthropathy.

Discussion

M marinum is an NTM found in bodies of water and marine settings. Infection arises after direct contact of lacerated skin with contaminated water. In a review article of 5 cases of M marinum tenosynovitis, they found that all individuals had wounds with exposure to fish or shrimp while in the water or while handling seafood.¹ The incidence of this infection is infrequent, estimated to be 0.04 cases per 100,000, with only about 25% of these cases presenting as tenosynovitis.² The incubation period ranges from 2 to 4 weeks.³ Late identification of this organism is common because of its slow development. For example, presentation from first exposure to symptom onset may take as long as 32 days.¹ In addition, in the same review, surgical intervention occurred in 63 days.¹ It has been reported that AFB stains are positive in just 9% of cases, which confounds diagnosis even more.⁴ After synovial tissue culture is obtained, it takes approximately 6 weeks for the organism to grow. Moreover, diagnosis may take longer if it is not suspected.⁵

Four types of M marinum infections have been described.⁵ The status of the immune system plays a role in how the manifestations present. The first type is limited, which is seen in immunocompetent persons, characterized by skin involvement, such as erythematous nodular lesions, that may improve on their own in months or years.⁴ Conversely, in immunosuppressed patients, the second type of infection may cause sporotrichoid spreading described as following lymphangitic pattern. The third type presents with musculoskeletal findings, such as arthritis, tenosynovitis, bursitis, or osteomyelitis, as seen in our patient. The fourth type consists of systemic manifestations.⁵ Medications that lower the immune system, such as corticosteroids, chemotherapy, and biologic disease modifying agents, may increase the risk for developing this entity.⁴ Specifically, antitumor necrosis factor inhibitors have been historically associated with mycobacterium infections.⁶

Patients are frequently diagnosed with soft tissue infection, such as abscesses or cellulitis, as in our case. They may at times be found to have other musculoskeletal conditions such as trigger finger.¹ Other similar presenting entities are psoriatic arthritis, rheumatoid arthritis, and remitting seronegative arthritis.⁴ These clinical resemblances complicate the scenario, especially when initial cultures are negative, as the treatment for these rheumatic diseases is immunosuppression, which adversely impact the fastidious infection. In our case, the improved swelling and range of motion after the 3-week course of empiric antibiotics for suppurative tenosynovitis was initially reassuring that the previous infection had been successfully treated. Subsequently, the presence of chondrocalcinosis in the triangular fibrocartilage in the right-hand X-rays, persistent pain, and the tophi-like appearance of the right third proximal interphalangeal nodule raised concerns for crystalline arthropathies, such as calcium pyrophosphate deposition vs gout. Nonetheless, given the lack of response to low-dose steroids, an ongoing infectious process was strongly considered.

Sarcoidosis was a concern after the first synovial biopsy revealed noncaseating granulomas and negative stains and cultures. Sarcoid tenosynovitis is rare with only 22 cases described as per a 2015 report.⁷ Musculoskeletal involvement in sarcoidosis has been reported in 1 to 13% of sarcoid patients.⁷ Once again, unresponsiveness to steroids led to another synovial biopsy for culture due to potential infection. Akin to other cases, more than one surgical debridement was required to diagnose our patient.

Conclusions

Our case reinforces the vital role of history gathering in establishing diagnoses. It underscores the value of clinical suspicion especially in patients unresponsive to standard treatment for inflammatory arthritis, namely corticosteroids. Tissue biopsy with culture for AFB is crucial for accurate diagnosis in NTM infection, which may imitate rheumatic inflammatory arthritis. Clinicians should be keenly aware of this fastidious, indolent organism in the setting of persistent localized tenosynovitis.

Rheumatologic conditions and infections may imitate each other, often making diagnosis challenging. Therefore, it is imperative to obtain adequate histories and have a keen eye for these potentially confounding differential diagnoses. Immunosuppressants used in managing rheumatologic etiologies have detrimental consequences in undiagnosed underlying infections. Consequently, worsening symptoms with standard therapy should raise awareness to a different diagnosis.

Nontuberculous mycobacteria (NTM) are slow-growing organisms difficult to yield in culture. Initial negative synovial fluid stains and cultures when suspecting NTM infectious arthritis or tenosynovitis should not exclude the diagnosis if there is a strong clinical scenario. The identification of Mycobacterium marinum (M marinum) infection in the hand is of utmost importance given that delayed treatment may cause significant and even permanent disability.

We present the case of a 73-year-old male patient with progressively worsening right-hand tenosynovitis who was evaluated for crystal-induced and sarcoid arthropathies in the setting of negative synovial biopsy cultures but was subsequently diagnosed with M marinum infectious tenosynovitis after a second surgical debridement.

Case Presentation

A 73-year-old male patient with history of type 2 diabetes mellitus, hypertension, hyperlipidemia, hypothyroidism, bilateral knee osteoarthritis, obstructive sleep apnea, and posttraumatic stress disorder presented to the emergency department (ED) with right wrist swelling and pain for 4 days. The patient reported that he was working in his garden when symptoms started. He did not recall any skin abrasions or wounds, insect bites, thorn punctures, trauma, or exposure to swimming pools or fish tanks. Patient was afebrile, and vital signs were within normal range. On physical examination, there was erythema, swelling, and tenderness in the dorsum of the right hand and over the dorsal aspect of the fourth metacarpophalangeal joint (Figure 1). The skin was intact.

Symptoms had not responded to 7 days of cefalexin nor to a short course of oral steroids. Leukocytosis of 14.35 × 10⁹/L (reference range, 3.90-9.90 × 10⁹/L) with neutrophilia at 11.10 × 10^9/L (reference range, 1.73-6.37 × 10⁹/L) was noted. Sedimentation rate and C-reactive protein levels were normal. Right-hand X-ray was remarkable for chondrocalcinosis in the triangular fibrocartilage. Right upper extremity magnetic resonance imaging (MRI) revealed diffuse inflammation in the right wrist and hand (Figure 2). There was no evidence of septic arthritis or osteomyelitis. Consequently, orthopedic service recommended no surgical intervention. Additionally, the patient had preserved range of motion that further indicated tenosynovitis, which could be medically managed with antibiotics, rather than a septic joint.

One dose of IV piperacillin/tazobactam was given at the ED, and he was admitted to the internal medicine ward with right hand and wrist cellulitis and indolent suppurative tenosynovitis. Empiric IV ceftriaxone and vancomycin were started as per infectious disease (ID) service with adequate response defined as a reduction of the swelling, erythema, and tenderness of the right hand and wrist. Differential diagnosis included sporotrichosis, nocardia vs NTM infection.

Interventional radiology was consulted for right wrist drainage. However, only 1 mL of fluid was obtained. Synovial fluid was sent for cell count and differential, crystal analysis, bacterial cultures, fungal cultures, and acid-fast bacilli (AFB) stains and culture. Neutrophils were 43% and lymphocytes were 57%. Crystal analysis was negative. Bacterial culture and mycology were negative. AFB stain and culture results were negative after 6 weeks. Based on gardening history and risk of thorn exposure and low suspicion for common bacterial pathogens, ID service switched antibiotics to moxifloxacin, minocycline, and linezolid for broad coverage to complete 3 weeks as outpatient. The patient reported significantly improved pain and handgrip with notable decrease in swelling. Nonetheless, 3 weeks after completing antibiotics, the right-hand pain recurred, raising concern for complex regional syndrome vs crystalline arthropathy.

Discussion

M marinum is an NTM found in bodies of water and marine settings. Infection arises after direct contact of lacerated skin with contaminated water. In a review article of 5 cases of M marinum tenosynovitis, they found that all individuals had wounds with exposure to fish or shrimp while in the water or while handling seafood.¹ The incidence of this infection is infrequent, estimated to be 0.04 cases per 100,000, with only about 25% of these cases presenting as tenosynovitis.² The incubation period ranges from 2 to 4 weeks.³ Late identification of this organism is common because of its slow development. For example, presentation from first exposure to symptom onset may take as long as 32 days.¹ In addition, in the same review, surgical intervention occurred in 63 days.¹ It has been reported that AFB stains are positive in just 9% of cases, which confounds diagnosis even more.⁴ After synovial tissue culture is obtained, it takes approximately 6 weeks for the organism to grow. Moreover, diagnosis may take longer if it is not suspected.⁵

Four types of M marinum infections have been described.⁵ The status of the immune system plays a role in how the manifestations present. The first type is limited, which is seen in immunocompetent persons, characterized by skin involvement, such as erythematous nodular lesions, that may improve on their own in months or years.⁴ Conversely, in immunosuppressed patients, the second type of infection may cause sporotrichoid spreading described as following lymphangitic pattern. The third type presents with musculoskeletal findings, such as arthritis, tenosynovitis, bursitis, or osteomyelitis, as seen in our patient. The fourth type consists of systemic manifestations.⁵ Medications that lower the immune system, such as corticosteroids, chemotherapy, and biologic disease modifying agents, may increase the risk for developing this entity.⁴ Specifically, antitumor necrosis factor inhibitors have been historically associated with mycobacterium infections.⁶

Patients are frequently diagnosed with soft tissue infection, such as abscesses or cellulitis, as in our case. They may at times be found to have other musculoskeletal conditions such as trigger finger.¹ Other similar presenting entities are psoriatic arthritis, rheumatoid arthritis, and remitting seronegative arthritis.⁴ These clinical resemblances complicate the scenario, especially when initial cultures are negative, as the treatment for these rheumatic diseases is immunosuppression, which adversely impact the fastidious infection. In our case, the improved swelling and range of motion after the 3-week course of empiric antibiotics for suppurative tenosynovitis was initially reassuring that the previous infection had been successfully treated. Subsequently, the presence of chondrocalcinosis in the triangular fibrocartilage in the right-hand X-rays, persistent pain, and the tophi-like appearance of the right third proximal interphalangeal nodule raised concerns for crystalline arthropathies, such as calcium pyrophosphate deposition vs gout. Nonetheless, given the lack of response to low-dose steroids, an ongoing infectious process was strongly considered.

Sarcoidosis was a concern after the first synovial biopsy revealed noncaseating granulomas and negative stains and cultures. Sarcoid tenosynovitis is rare with only 22 cases described as per a 2015 report.⁷ Musculoskeletal involvement in sarcoidosis has been reported in 1 to 13% of sarcoid patients.⁷ Once again, unresponsiveness to steroids led to another synovial biopsy for culture due to potential infection. Akin to other cases, more than one surgical debridement was required to diagnose our patient.

Conclusions

Our case reinforces the vital role of history gathering in establishing diagnoses. It underscores the value of clinical suspicion especially in patients unresponsive to standard treatment for inflammatory arthritis, namely corticosteroids. Tissue biopsy with culture for AFB is crucial for accurate diagnosis in NTM infection, which may imitate rheumatic inflammatory arthritis. Clinicians should be keenly aware of this fastidious, indolent organism in the setting of persistent localized tenosynovitis.

Rheumatologic conditions and infections may imitate each other, often making diagnosis challenging. Therefore, it is imperative to obtain adequate histories and have a keen eye for these potentially confounding differential diagnoses. Immunosuppressants used in managing rheumatologic etiologies have detrimental consequences in undiagnosed underlying infections. Consequently, worsening symptoms with standard therapy should raise awareness to a different diagnosis.

Nontuberculous mycobacteria (NTM) are slow-growing organisms difficult to yield in culture. Initial negative synovial fluid stains and cultures when suspecting NTM infectious arthritis or tenosynovitis should not exclude the diagnosis if there is a strong clinical scenario. The identification of Mycobacterium marinum (M marinum) infection in the hand is of utmost importance given that delayed treatment may cause significant and even permanent disability.

We present the case of a 73-year-old male patient with progressively worsening right-hand tenosynovitis who was evaluated for crystal-induced and sarcoid arthropathies in the setting of negative synovial biopsy cultures but was subsequently diagnosed with M marinum infectious tenosynovitis after a second surgical debridement.

Case Presentation

A 73-year-old male patient with history of type 2 diabetes mellitus, hypertension, hyperlipidemia, hypothyroidism, bilateral knee osteoarthritis, obstructive sleep apnea, and posttraumatic stress disorder presented to the emergency department (ED) with right wrist swelling and pain for 4 days. The patient reported that he was working in his garden when symptoms started. He did not recall any skin abrasions or wounds, insect bites, thorn punctures, trauma, or exposure to swimming pools or fish tanks. Patient was afebrile, and vital signs were within normal range. On physical examination, there was erythema, swelling, and tenderness in the dorsum of the right hand and over the dorsal aspect of the fourth metacarpophalangeal joint (Figure 1). The skin was intact.

Symptoms had not responded to 7 days of cefalexin nor to a short course of oral steroids. Leukocytosis of 14.35 × 10⁹/L (reference range, 3.90-9.90 × 10⁹/L) with neutrophilia at 11.10 × 10^9/L (reference range, 1.73-6.37 × 10⁹/L) was noted. Sedimentation rate and C-reactive protein levels were normal. Right-hand X-ray was remarkable for chondrocalcinosis in the triangular fibrocartilage. Right upper extremity magnetic resonance imaging (MRI) revealed diffuse inflammation in the right wrist and hand (Figure 2). There was no evidence of septic arthritis or osteomyelitis. Consequently, orthopedic service recommended no surgical intervention. Additionally, the patient had preserved range of motion that further indicated tenosynovitis, which could be medically managed with antibiotics, rather than a septic joint.

One dose of IV piperacillin/tazobactam was given at the ED, and he was admitted to the internal medicine ward with right hand and wrist cellulitis and indolent suppurative tenosynovitis. Empiric IV ceftriaxone and vancomycin were started as per infectious disease (ID) service with adequate response defined as a reduction of the swelling, erythema, and tenderness of the right hand and wrist. Differential diagnosis included sporotrichosis, nocardia vs NTM infection.

Interventional radiology was consulted for right wrist drainage. However, only 1 mL of fluid was obtained. Synovial fluid was sent for cell count and differential, crystal analysis, bacterial cultures, fungal cultures, and acid-fast bacilli (AFB) stains and culture. Neutrophils were 43% and lymphocytes were 57%. Crystal analysis was negative. Bacterial culture and mycology were negative. AFB stain and culture results were negative after 6 weeks. Based on gardening history and risk of thorn exposure and low suspicion for common bacterial pathogens, ID service switched antibiotics to moxifloxacin, minocycline, and linezolid for broad coverage to complete 3 weeks as outpatient. The patient reported significantly improved pain and handgrip with notable decrease in swelling. Nonetheless, 3 weeks after completing antibiotics, the right-hand pain recurred, raising concern for complex regional syndrome vs crystalline arthropathy.

Discussion

M marinum is an NTM found in bodies of water and marine settings. Infection arises after direct contact of lacerated skin with contaminated water. In a review article of 5 cases of M marinum tenosynovitis, they found that all individuals had wounds with exposure to fish or shrimp while in the water or while handling seafood.¹ The incidence of this infection is infrequent, estimated to be 0.04 cases per 100,000, with only about 25% of these cases presenting as tenosynovitis.² The incubation period ranges from 2 to 4 weeks.³ Late identification of this organism is common because of its slow development. For example, presentation from first exposure to symptom onset may take as long as 32 days.¹ In addition, in the same review, surgical intervention occurred in 63 days.¹ It has been reported that AFB stains are positive in just 9% of cases, which confounds diagnosis even more.⁴ After synovial tissue culture is obtained, it takes approximately 6 weeks for the organism to grow. Moreover, diagnosis may take longer if it is not suspected.⁵

Four types of M marinum infections have been described.⁵ The status of the immune system plays a role in how the manifestations present. The first type is limited, which is seen in immunocompetent persons, characterized by skin involvement, such as erythematous nodular lesions, that may improve on their own in months or years.⁴ Conversely, in immunosuppressed patients, the second type of infection may cause sporotrichoid spreading described as following lymphangitic pattern. The third type presents with musculoskeletal findings, such as arthritis, tenosynovitis, bursitis, or osteomyelitis, as seen in our patient. The fourth type consists of systemic manifestations.⁵ Medications that lower the immune system, such as corticosteroids, chemotherapy, and biologic disease modifying agents, may increase the risk for developing this entity.⁴ Specifically, antitumor necrosis factor inhibitors have been historically associated with mycobacterium infections.⁶

Patients are frequently diagnosed with soft tissue infection, such as abscesses or cellulitis, as in our case. They may at times be found to have other musculoskeletal conditions such as trigger finger.¹ Other similar presenting entities are psoriatic arthritis, rheumatoid arthritis, and remitting seronegative arthritis.⁴ These clinical resemblances complicate the scenario, especially when initial cultures are negative, as the treatment for these rheumatic diseases is immunosuppression, which adversely impact the fastidious infection. In our case, the improved swelling and range of motion after the 3-week course of empiric antibiotics for suppurative tenosynovitis was initially reassuring that the previous infection had been successfully treated. Subsequently, the presence of chondrocalcinosis in the triangular fibrocartilage in the right-hand X-rays, persistent pain, and the tophi-like appearance of the right third proximal interphalangeal nodule raised concerns for crystalline arthropathies, such as calcium pyrophosphate deposition vs gout. Nonetheless, given the lack of response to low-dose steroids, an ongoing infectious process was strongly considered.

Sarcoidosis was a concern after the first synovial biopsy revealed noncaseating granulomas and negative stains and cultures. Sarcoid tenosynovitis is rare with only 22 cases described as per a 2015 report.⁷ Musculoskeletal involvement in sarcoidosis has been reported in 1 to 13% of sarcoid patients.⁷ Once again, unresponsiveness to steroids led to another synovial biopsy for culture due to potential infection. Akin to other cases, more than one surgical debridement was required to diagnose our patient.

Conclusions

Our case reinforces the vital role of history gathering in establishing diagnoses. It underscores the value of clinical suspicion especially in patients unresponsive to standard treatment for inflammatory arthritis, namely corticosteroids. Tissue biopsy with culture for AFB is crucial for accurate diagnosis in NTM infection, which may imitate rheumatic inflammatory arthritis. Clinicians should be keenly aware of this fastidious, indolent organism in the setting of persistent localized tenosynovitis.

The brachial plexus is a group of interwoven nerves arising from the cervical spinal cord and coursing through the neck, shoulder, and axilla with terminal branches extending to the distal arm.¹ Disorders of the brachial plexus are more rare than other isolated peripheral nerve disorders, trauma being the most common etiology.¹ Traction, neoplasms, radiation exposure, external compression, and inflammatory processes, such as Parsonage-Turner syndrome, have also been described as less common etiologies.²

Rhabdomyolysis, a condition in which muscle breakdown occurs, is an uncommon and perhaps underrecognized cause of brachial plexopathy. Rhabdomyolysis is often caused by muscle overuse, trauma, prolonged immobilization, drugs, or toxins. Substances indicated as precipitating factors include alcohol, opioids, cocaine, and amphetamines.^3,4 As rhabdomyolysis progresses, swelling and edema can compress surrounding structures. Therefore, in cases of rhabdomyolysis involving the muscles of the neck and shoulder girdle, external compression of the brachial plexus can potentially cause brachial plexopathy. Rare cases of this phenomenon occurring as a sequela of substance use have been described.^1,5-9 Few cases have been reported in the literature.

The following case report describes a patient who experienced rhabdomyolysis following use of crack cocaine contaminated with fentanyl, which subsequently caused bilateral brachial plexopathy. 

Case Presentation

A 68-year-old male patient with a history of polysubstance use disorder presented to the emergency department with complete loss of sensory and motor function of both arms. He had fallen asleep on his couch the previous evening with his arms crossed over his chest in the prone position. He reported using crack cocaine earlier that day that was later discovered to be contaminated with fentanyl. The patient reported using no other substances, including alcohol. When he woke about 7 hours later, the patient’s arms were completely paralyzed.

On admission, the patient presented with an agitated mental status. The patient presented with 0/5 strength bilaterally in the upper extremities (UEs) accompanied by numbness and tingling. Radial pulses were palpable in both arms. All UE reflexes were absent, but patellar reflex was intact bilaterally. On hospital day 2, the patient was awake, alert, and oriented to person, place, and time and could provide a full history. The patient’s cranial nerves were intact with shoulder shrug testing mildly weak at 4/5 strength. The patient had 0/5 strength bilaterally and bilateral absent reflexes in the UEs. Sensation was markedly decreased, as he was unable to feel temperature, pinprick sensation, or general touch in both UEs. Coordination of the UEs could not be tested due to weakness. No response could be elicited from the median or ulnar nerve bilaterally on somatosensory evoked potential study. The lower extremities were intact to movement, sensation, coordination, and reflexes.

Serum electrolytes and glucose levels were normal. The creatine phosphokinase (CPK) level was elevated at 21,292 IU/L. Creatinine and blood urea nitrogen levels were elevated at 1.7 mg/dL and 32 mg/dL, respectively. Serum B12, thyroid-stimulating hormone, and hemoglobin A_1c levels were normal. Urine drug screen was positive for cocaine metabolite and fentanyl but negative for other substances, including alcohol. The patient stated emphatically he had only used crack cocaine, so it was presumed that the crack cocaine had been contaminated with fentanyl.

Computed tomography (CT) of the head was normal and revealed no acute intracranial process. Further imaging studies included magnetic resonance imaging (MRI) of the brain and spinal cord and subsequently of the brachial plexus. There was no evidence of a spinal cord or intracranial lesion. However, there was abnormal signal in the lower neck greater on the right side suggesting an edematous inflammatory process involving part of the shoulder girdle musculature. This included the trapezius, levator scapula, rhomboid, and serratus anterior muscles, as well as prominent fluid signal in the right supraclavicular fossa. The abnormal signal was less prominent on the left and involved the serratus anterior muscle. To a lesser extent, there also was involvement of the distal attachment site of the anterior and middle scalene muscles on the right greater than the left. It is presumed that muscular edema resulted in partial narrowing of the thoracic outlet bilaterally with corresponding mass effect on the traversing brachial plexus, resulting in the patient’s symptoms (Figure).

Discussion

Rhabdomyolysis is a condition defined by myocyte necrosis that results in release of cellular contents and local edema. Inciting events may be traumatic, metabolic, ischemic, or substance induced. Common substances indicated include cocaine, amphetamines, acetaminophen, opioids, and alcohol.¹⁰ It classically presents with muscle pain and a marked elevation in serum CPK level, but other metabolic disturbances, acute kidney injury, or toxic hepatitis may also occur. A more uncommon sequela of rhabdomyolysis is plexopathy caused by edematous swelling and compression of the surrounding structures.

Rare cases of brachial plexopathy caused by rhabdomyolysis following substance use have been described. In many of these cases, rhabdomyolysis occurred after alcohol use with or without concurrent use of prescription opioids or heroin.^7-9 One case following use of 3,4-methylenedioxy-N-methylamptamine (MDMA) and marijuana use was reported.¹ Another case of concurrent brachial plexopathy and Horner syndrome in a 29-year-old male patient following ingestion of alcohol and opioids has also been described.⁵ The rate of occurrence of this phenomenon in the general population is unknown.

In the case of our patient, cocaine metabolite and fentanyl were the only substances found on urine drug screen. The patient had used crack cocaine that had presumably been contaminated with fentanyl, a high potency synthetic opioid. The rate of fentanyl contamination of street drugs is variable. It is a subject of high concern, considering the increasing rates of synthetic opioid overdose-related deaths. According to the US Centers for Disease Control and Prevention, synthetic opioids have played a role in the increasing rates of cocaine-related overdose deaths. Conversely, in more than half of all overdose deaths involving fentanyl derivatives, patients also tested positive for cocaine, methamphetamine, or heroin. In recent studies conducted in various cities in the northeastern US, rates of fentanyl metabolite detection were much higher than rates of reported fentanyl use.¹¹ Cases of crack cocaine contamination with fentanyl derivatives have been reported in Canada and Washington.¹²

The pathophysiology of rhabdomyolysis caused by substance use has not been definitively identified, but it is hypothesized that the cause is 2-fold. The first insult is the direct toxicity of the substances to myocytes.^8,9 The second factor is prolonged immobilization in a position that compresses the affected musculature and blood supply, causing both mechanical stress and ischemia to the muscles and brachial plexus. This prolonged immobilization can frequently follow use of substances, such as alcohol or opioids.⁹ Cases have been reported wherein rhabdomyolysis causing brachial plexopathy occurred despite relatively normal positioning of the arms and shoulders during sleep.⁹ In our case, the patient had fallen asleep with his arms crossed over his chest in the prone position with his head turned, though he could not recall to which side. Although he stated that he had slept in this position regularly, the effects of fentanyl may have prevented the patient from waking to adjust his posture. This position had potential to compress the musculature of the neck and shoulders and restrict blood flow, resulting in the focal rhabdomyolysis seen in this patient. In theory, the position could also cause a stretch injury of the brachial plexus, although a pure stretch injury would more likely present unilaterally and without evidence of rhabdomyolysis.

Chronic ethanol use may have been a major contributor by both sensitizing the muscles to toxicity of other substances and induction of CYP450 enzymes that are normally responsible for metabolizing other drugs.⁸ Alcohol also inhibits gluconeogenesis and leads to hyperpolarization of myocytes, further contributing to their susceptibility to damage.⁹ Our patient had a prior history of alcohol use years before this event, but not at the time of this event.

Our patient had other known risk factors for rhabdomyolysis, including his long-term statin therapy, but it is unclear whether these were contributing factors in his case.¹⁰ Of the medications that are known to cause rhabdomyolysis, statins are among the most commonly described, although the mechanism through which this process occurs is not clear. A case of rhabdomyolysis following use of cocaine and heroin in a patient on long-standing statin therapy has been described.¹³ Our review of the literature found no cases of statin-induced rhabdomyolysis associated with brachial plexopathy. It is possible that concurrent statin therapy has an additive effect to other substances in inducing rhabdomyolysis.

Parsonage-Turner syndrome, also known as neuralgic amyotrophy, should also be included in the differential diagnosis. While there have been multiple etiologies proposed for Parsonage-Turner syndrome, it is generally thought to begin as a primary inflammatory process targeting the brachial plexus. One case report describes Parsonage-Turner syndrome progressing to secondary rhabdomyolysis.⁶ In this case, no primary etiology was identified, so the Parsonage-Turner syndrome diagnosis was made with secondary rhabdomyolysis.⁶ We believe it is possible that this case and others may have been misdiagnosed as Parsonage-Turner syndrome.

Conclusions

This case report adds to the literature describing focal rhabdomyolysis causing secondary bilateral brachial plexopathy after substance use. Further research is needed to establish a definitive pathophysiology as well as treatment guidelines. Evidence-based treatment could mean better outcomes and quicker recoveries for future patients with this condition.

The brachial plexus is a group of interwoven nerves arising from the cervical spinal cord and coursing through the neck, shoulder, and axilla with terminal branches extending to the distal arm.¹ Disorders of the brachial plexus are more rare than other isolated peripheral nerve disorders, trauma being the most common etiology.¹ Traction, neoplasms, radiation exposure, external compression, and inflammatory processes, such as Parsonage-Turner syndrome, have also been described as less common etiologies.²

Rhabdomyolysis, a condition in which muscle breakdown occurs, is an uncommon and perhaps underrecognized cause of brachial plexopathy. Rhabdomyolysis is often caused by muscle overuse, trauma, prolonged immobilization, drugs, or toxins. Substances indicated as precipitating factors include alcohol, opioids, cocaine, and amphetamines.^3,4 As rhabdomyolysis progresses, swelling and edema can compress surrounding structures. Therefore, in cases of rhabdomyolysis involving the muscles of the neck and shoulder girdle, external compression of the brachial plexus can potentially cause brachial plexopathy. Rare cases of this phenomenon occurring as a sequela of substance use have been described.^1,5-9 Few cases have been reported in the literature.

The following case report describes a patient who experienced rhabdomyolysis following use of crack cocaine contaminated with fentanyl, which subsequently caused bilateral brachial plexopathy. 

Case Presentation

A 68-year-old male patient with a history of polysubstance use disorder presented to the emergency department with complete loss of sensory and motor function of both arms. He had fallen asleep on his couch the previous evening with his arms crossed over his chest in the prone position. He reported using crack cocaine earlier that day that was later discovered to be contaminated with fentanyl. The patient reported using no other substances, including alcohol. When he woke about 7 hours later, the patient’s arms were completely paralyzed.

On admission, the patient presented with an agitated mental status. The patient presented with 0/5 strength bilaterally in the upper extremities (UEs) accompanied by numbness and tingling. Radial pulses were palpable in both arms. All UE reflexes were absent, but patellar reflex was intact bilaterally. On hospital day 2, the patient was awake, alert, and oriented to person, place, and time and could provide a full history. The patient’s cranial nerves were intact with shoulder shrug testing mildly weak at 4/5 strength. The patient had 0/5 strength bilaterally and bilateral absent reflexes in the UEs. Sensation was markedly decreased, as he was unable to feel temperature, pinprick sensation, or general touch in both UEs. Coordination of the UEs could not be tested due to weakness. No response could be elicited from the median or ulnar nerve bilaterally on somatosensory evoked potential study. The lower extremities were intact to movement, sensation, coordination, and reflexes.

Serum electrolytes and glucose levels were normal. The creatine phosphokinase (CPK) level was elevated at 21,292 IU/L. Creatinine and blood urea nitrogen levels were elevated at 1.7 mg/dL and 32 mg/dL, respectively. Serum B12, thyroid-stimulating hormone, and hemoglobin A_1c levels were normal. Urine drug screen was positive for cocaine metabolite and fentanyl but negative for other substances, including alcohol. The patient stated emphatically he had only used crack cocaine, so it was presumed that the crack cocaine had been contaminated with fentanyl.

Computed tomography (CT) of the head was normal and revealed no acute intracranial process. Further imaging studies included magnetic resonance imaging (MRI) of the brain and spinal cord and subsequently of the brachial plexus. There was no evidence of a spinal cord or intracranial lesion. However, there was abnormal signal in the lower neck greater on the right side suggesting an edematous inflammatory process involving part of the shoulder girdle musculature. This included the trapezius, levator scapula, rhomboid, and serratus anterior muscles, as well as prominent fluid signal in the right supraclavicular fossa. The abnormal signal was less prominent on the left and involved the serratus anterior muscle. To a lesser extent, there also was involvement of the distal attachment site of the anterior and middle scalene muscles on the right greater than the left. It is presumed that muscular edema resulted in partial narrowing of the thoracic outlet bilaterally with corresponding mass effect on the traversing brachial plexus, resulting in the patient’s symptoms (Figure).

Discussion

Rhabdomyolysis is a condition defined by myocyte necrosis that results in release of cellular contents and local edema. Inciting events may be traumatic, metabolic, ischemic, or substance induced. Common substances indicated include cocaine, amphetamines, acetaminophen, opioids, and alcohol.¹⁰ It classically presents with muscle pain and a marked elevation in serum CPK level, but other metabolic disturbances, acute kidney injury, or toxic hepatitis may also occur. A more uncommon sequela of rhabdomyolysis is plexopathy caused by edematous swelling and compression of the surrounding structures.

Rare cases of brachial plexopathy caused by rhabdomyolysis following substance use have been described. In many of these cases, rhabdomyolysis occurred after alcohol use with or without concurrent use of prescription opioids or heroin.^7-9 One case following use of 3,4-methylenedioxy-N-methylamptamine (MDMA) and marijuana use was reported.¹ Another case of concurrent brachial plexopathy and Horner syndrome in a 29-year-old male patient following ingestion of alcohol and opioids has also been described.⁵ The rate of occurrence of this phenomenon in the general population is unknown.

In the case of our patient, cocaine metabolite and fentanyl were the only substances found on urine drug screen. The patient had used crack cocaine that had presumably been contaminated with fentanyl, a high potency synthetic opioid. The rate of fentanyl contamination of street drugs is variable. It is a subject of high concern, considering the increasing rates of synthetic opioid overdose-related deaths. According to the US Centers for Disease Control and Prevention, synthetic opioids have played a role in the increasing rates of cocaine-related overdose deaths. Conversely, in more than half of all overdose deaths involving fentanyl derivatives, patients also tested positive for cocaine, methamphetamine, or heroin. In recent studies conducted in various cities in the northeastern US, rates of fentanyl metabolite detection were much higher than rates of reported fentanyl use.¹¹ Cases of crack cocaine contamination with fentanyl derivatives have been reported in Canada and Washington.¹²

The pathophysiology of rhabdomyolysis caused by substance use has not been definitively identified, but it is hypothesized that the cause is 2-fold. The first insult is the direct toxicity of the substances to myocytes.^8,9 The second factor is prolonged immobilization in a position that compresses the affected musculature and blood supply, causing both mechanical stress and ischemia to the muscles and brachial plexus. This prolonged immobilization can frequently follow use of substances, such as alcohol or opioids.⁹ Cases have been reported wherein rhabdomyolysis causing brachial plexopathy occurred despite relatively normal positioning of the arms and shoulders during sleep.⁹ In our case, the patient had fallen asleep with his arms crossed over his chest in the prone position with his head turned, though he could not recall to which side. Although he stated that he had slept in this position regularly, the effects of fentanyl may have prevented the patient from waking to adjust his posture. This position had potential to compress the musculature of the neck and shoulders and restrict blood flow, resulting in the focal rhabdomyolysis seen in this patient. In theory, the position could also cause a stretch injury of the brachial plexus, although a pure stretch injury would more likely present unilaterally and without evidence of rhabdomyolysis.

Chronic ethanol use may have been a major contributor by both sensitizing the muscles to toxicity of other substances and induction of CYP450 enzymes that are normally responsible for metabolizing other drugs.⁸ Alcohol also inhibits gluconeogenesis and leads to hyperpolarization of myocytes, further contributing to their susceptibility to damage.⁹ Our patient had a prior history of alcohol use years before this event, but not at the time of this event.

Our patient had other known risk factors for rhabdomyolysis, including his long-term statin therapy, but it is unclear whether these were contributing factors in his case.¹⁰ Of the medications that are known to cause rhabdomyolysis, statins are among the most commonly described, although the mechanism through which this process occurs is not clear. A case of rhabdomyolysis following use of cocaine and heroin in a patient on long-standing statin therapy has been described.¹³ Our review of the literature found no cases of statin-induced rhabdomyolysis associated with brachial plexopathy. It is possible that concurrent statin therapy has an additive effect to other substances in inducing rhabdomyolysis.

Parsonage-Turner syndrome, also known as neuralgic amyotrophy, should also be included in the differential diagnosis. While there have been multiple etiologies proposed for Parsonage-Turner syndrome, it is generally thought to begin as a primary inflammatory process targeting the brachial plexus. One case report describes Parsonage-Turner syndrome progressing to secondary rhabdomyolysis.⁶ In this case, no primary etiology was identified, so the Parsonage-Turner syndrome diagnosis was made with secondary rhabdomyolysis.⁶ We believe it is possible that this case and others may have been misdiagnosed as Parsonage-Turner syndrome.

Conclusions

This case report adds to the literature describing focal rhabdomyolysis causing secondary bilateral brachial plexopathy after substance use. Further research is needed to establish a definitive pathophysiology as well as treatment guidelines. Evidence-based treatment could mean better outcomes and quicker recoveries for future patients with this condition.

The brachial plexus is a group of interwoven nerves arising from the cervical spinal cord and coursing through the neck, shoulder, and axilla with terminal branches extending to the distal arm.¹ Disorders of the brachial plexus are more rare than other isolated peripheral nerve disorders, trauma being the most common etiology.¹ Traction, neoplasms, radiation exposure, external compression, and inflammatory processes, such as Parsonage-Turner syndrome, have also been described as less common etiologies.²

Rhabdomyolysis, a condition in which muscle breakdown occurs, is an uncommon and perhaps underrecognized cause of brachial plexopathy. Rhabdomyolysis is often caused by muscle overuse, trauma, prolonged immobilization, drugs, or toxins. Substances indicated as precipitating factors include alcohol, opioids, cocaine, and amphetamines.^3,4 As rhabdomyolysis progresses, swelling and edema can compress surrounding structures. Therefore, in cases of rhabdomyolysis involving the muscles of the neck and shoulder girdle, external compression of the brachial plexus can potentially cause brachial plexopathy. Rare cases of this phenomenon occurring as a sequela of substance use have been described.^1,5-9 Few cases have been reported in the literature.

The following case report describes a patient who experienced rhabdomyolysis following use of crack cocaine contaminated with fentanyl, which subsequently caused bilateral brachial plexopathy. 

Case Presentation

A 68-year-old male patient with a history of polysubstance use disorder presented to the emergency department with complete loss of sensory and motor function of both arms. He had fallen asleep on his couch the previous evening with his arms crossed over his chest in the prone position. He reported using crack cocaine earlier that day that was later discovered to be contaminated with fentanyl. The patient reported using no other substances, including alcohol. When he woke about 7 hours later, the patient’s arms were completely paralyzed.

On admission, the patient presented with an agitated mental status. The patient presented with 0/5 strength bilaterally in the upper extremities (UEs) accompanied by numbness and tingling. Radial pulses were palpable in both arms. All UE reflexes were absent, but patellar reflex was intact bilaterally. On hospital day 2, the patient was awake, alert, and oriented to person, place, and time and could provide a full history. The patient’s cranial nerves were intact with shoulder shrug testing mildly weak at 4/5 strength. The patient had 0/5 strength bilaterally and bilateral absent reflexes in the UEs. Sensation was markedly decreased, as he was unable to feel temperature, pinprick sensation, or general touch in both UEs. Coordination of the UEs could not be tested due to weakness. No response could be elicited from the median or ulnar nerve bilaterally on somatosensory evoked potential study. The lower extremities were intact to movement, sensation, coordination, and reflexes.

Serum electrolytes and glucose levels were normal. The creatine phosphokinase (CPK) level was elevated at 21,292 IU/L. Creatinine and blood urea nitrogen levels were elevated at 1.7 mg/dL and 32 mg/dL, respectively. Serum B12, thyroid-stimulating hormone, and hemoglobin A_1c levels were normal. Urine drug screen was positive for cocaine metabolite and fentanyl but negative for other substances, including alcohol. The patient stated emphatically he had only used crack cocaine, so it was presumed that the crack cocaine had been contaminated with fentanyl.

Computed tomography (CT) of the head was normal and revealed no acute intracranial process. Further imaging studies included magnetic resonance imaging (MRI) of the brain and spinal cord and subsequently of the brachial plexus. There was no evidence of a spinal cord or intracranial lesion. However, there was abnormal signal in the lower neck greater on the right side suggesting an edematous inflammatory process involving part of the shoulder girdle musculature. This included the trapezius, levator scapula, rhomboid, and serratus anterior muscles, as well as prominent fluid signal in the right supraclavicular fossa. The abnormal signal was less prominent on the left and involved the serratus anterior muscle. To a lesser extent, there also was involvement of the distal attachment site of the anterior and middle scalene muscles on the right greater than the left. It is presumed that muscular edema resulted in partial narrowing of the thoracic outlet bilaterally with corresponding mass effect on the traversing brachial plexus, resulting in the patient’s symptoms (Figure).

Discussion

Rhabdomyolysis is a condition defined by myocyte necrosis that results in release of cellular contents and local edema. Inciting events may be traumatic, metabolic, ischemic, or substance induced. Common substances indicated include cocaine, amphetamines, acetaminophen, opioids, and alcohol.¹⁰ It classically presents with muscle pain and a marked elevation in serum CPK level, but other metabolic disturbances, acute kidney injury, or toxic hepatitis may also occur. A more uncommon sequela of rhabdomyolysis is plexopathy caused by edematous swelling and compression of the surrounding structures.

Rare cases of brachial plexopathy caused by rhabdomyolysis following substance use have been described. In many of these cases, rhabdomyolysis occurred after alcohol use with or without concurrent use of prescription opioids or heroin.^7-9 One case following use of 3,4-methylenedioxy-N-methylamptamine (MDMA) and marijuana use was reported.¹ Another case of concurrent brachial plexopathy and Horner syndrome in a 29-year-old male patient following ingestion of alcohol and opioids has also been described.⁵ The rate of occurrence of this phenomenon in the general population is unknown.

In the case of our patient, cocaine metabolite and fentanyl were the only substances found on urine drug screen. The patient had used crack cocaine that had presumably been contaminated with fentanyl, a high potency synthetic opioid. The rate of fentanyl contamination of street drugs is variable. It is a subject of high concern, considering the increasing rates of synthetic opioid overdose-related deaths. According to the US Centers for Disease Control and Prevention, synthetic opioids have played a role in the increasing rates of cocaine-related overdose deaths. Conversely, in more than half of all overdose deaths involving fentanyl derivatives, patients also tested positive for cocaine, methamphetamine, or heroin. In recent studies conducted in various cities in the northeastern US, rates of fentanyl metabolite detection were much higher than rates of reported fentanyl use.¹¹ Cases of crack cocaine contamination with fentanyl derivatives have been reported in Canada and Washington.¹²

The pathophysiology of rhabdomyolysis caused by substance use has not been definitively identified, but it is hypothesized that the cause is 2-fold. The first insult is the direct toxicity of the substances to myocytes.^8,9 The second factor is prolonged immobilization in a position that compresses the affected musculature and blood supply, causing both mechanical stress and ischemia to the muscles and brachial plexus. This prolonged immobilization can frequently follow use of substances, such as alcohol or opioids.⁹ Cases have been reported wherein rhabdomyolysis causing brachial plexopathy occurred despite relatively normal positioning of the arms and shoulders during sleep.⁹ In our case, the patient had fallen asleep with his arms crossed over his chest in the prone position with his head turned, though he could not recall to which side. Although he stated that he had slept in this position regularly, the effects of fentanyl may have prevented the patient from waking to adjust his posture. This position had potential to compress the musculature of the neck and shoulders and restrict blood flow, resulting in the focal rhabdomyolysis seen in this patient. In theory, the position could also cause a stretch injury of the brachial plexus, although a pure stretch injury would more likely present unilaterally and without evidence of rhabdomyolysis.

Chronic ethanol use may have been a major contributor by both sensitizing the muscles to toxicity of other substances and induction of CYP450 enzymes that are normally responsible for metabolizing other drugs.⁸ Alcohol also inhibits gluconeogenesis and leads to hyperpolarization of myocytes, further contributing to their susceptibility to damage.⁹ Our patient had a prior history of alcohol use years before this event, but not at the time of this event.

Our patient had other known risk factors for rhabdomyolysis, including his long-term statin therapy, but it is unclear whether these were contributing factors in his case.¹⁰ Of the medications that are known to cause rhabdomyolysis, statins are among the most commonly described, although the mechanism through which this process occurs is not clear. A case of rhabdomyolysis following use of cocaine and heroin in a patient on long-standing statin therapy has been described.¹³ Our review of the literature found no cases of statin-induced rhabdomyolysis associated with brachial plexopathy. It is possible that concurrent statin therapy has an additive effect to other substances in inducing rhabdomyolysis.

Parsonage-Turner syndrome, also known as neuralgic amyotrophy, should also be included in the differential diagnosis. While there have been multiple etiologies proposed for Parsonage-Turner syndrome, it is generally thought to begin as a primary inflammatory process targeting the brachial plexus. One case report describes Parsonage-Turner syndrome progressing to secondary rhabdomyolysis.⁶ In this case, no primary etiology was identified, so the Parsonage-Turner syndrome diagnosis was made with secondary rhabdomyolysis.⁶ We believe it is possible that this case and others may have been misdiagnosed as Parsonage-Turner syndrome.

Conclusions

This case report adds to the literature describing focal rhabdomyolysis causing secondary bilateral brachial plexopathy after substance use. Further research is needed to establish a definitive pathophysiology as well as treatment guidelines. Evidence-based treatment could mean better outcomes and quicker recoveries for future patients with this condition.

Pneumatosis intestinalis (PI) is the finding of gas within the walls of the intestine on imaging. It is most commonly detected via radiograph or computed tomography (CT). The diseases leading to the accumulation of gas within the submucosal space of the gastrointestinal (GI) tract are heterogenous, and the finding of PI itself has a wide range of clinical implications from impending clinical deterioration to an incidental finding of minimal consequence.

We present the case of a veteran who had sustained a remote anoxic brain injury resulting in chronic dependence on a gastrostomy tube for enteral nutrition, found incidentally to have PI without signs of intra-abdominal catastrophe. An exclusion of other, more lifethreatening causes of PI led to a diagnosis of benign PI secondary to the presence of his gastrostomy tube. This case highlights the importance of interpreting the finding of PI in the clinical context of the specific patient and how conservative management may be appropriate in some cases.

Case Presentation

A 61-year-old male patient was admitted for fever. The patient had a remote history of cardiac arrest complicated by anoxic brain injury requiring tracheostomy, gastrostomy tube, and a suprapubic catheter with recurrent catheter-associated urinary tract infections (CAUTI), secondary seizure disorder, atrial fibrillation off anticoagulation due to recurrent GI bleeding, and treatment naive chronic hepatitis C virus. His ability to provide a clinical history was limited by his nonverbal status. He had no prior surgical history but had presented a month earlier for a high-grade small bowel obstruction (SBO) with pneumobilia that was managed conservatively as the surgical team deemed him a poor candidate for surgical intervention with his extensive comorbidities. A bioethics consultation at the time supported minimizing potential surgical risk in favor of conservative medical management; this was discussed with the patient’s surrogate decision maker, who also wished to avoid surgery. The SBO resolved with conservative management. He had been residing in a nursing home and doing well until 24 hours prior to admission when he developed fevers.

Vital signs on admission showed a temperature of 100.8 °F, heart rate 100 beats per minute, blood pressure 116/85, respiratory rate 22 per minute, and oxygen saturation of 100% on 6 L of oxygen via tracheostomy collar. His initial examination was notable for clear lung sounds, a nondistended nonrigid abdomen with an indwelling percutaneous gastrostomy tube, and absence of areas of skin breakdown or erythema. Notable laboratory studies showed a leukocytosis and urinalysis suggestive of CAUTI (Table). His urinary catheter was exchanged, he was fluid resuscitated and started on empiric vancomycin and piperacillin-tazobactam for management of sepsis due to CAUTI.

For the first 3 days of his hospitalization, he demonstrated clinical improvement on vancomycin and piperacillin-tazobactam while awaiting results from his urine bacterial culture. On hospital day 3, hedeveloped recurrent nonbloody, nonbilious emesis despite no change in the rate or formulation of his enteral nutrition. He also had 3 watery brown bowel movements. His vital signs remained within normal limits. His abdominal examination at this point showed mild distention and was hypertympanic to percussion, but there was no rigidity or involuntary guarding. On hospital day 4, he continued to have emesis with an unchanged abdominal examination. The differential diagnosis included recurrence of prior SBO, ileus, intestinal ischemia, enteral nutrition intolerance, Clostridioides difficile (C difficile) colitis, and GI dysmotility because of his anoxic brain injury.

Testing for C difficile was negative. An abdominal radiograph was obtained and revealed no bowel obstruction but, alarmingly, showed extensive intramural bowel gas, suggestive of PI (Figure 1). His leukocyte count, serum bicarbonate, and serum lactate levels remained within normal limits. A CT with contrast of the abdomen and pelvis demonstrated no vascular obstruction but confirmed the presence of diffuse intramural gas in his stomach and proximal small bowel, as well as the presence of mesenteric and portal venous gas (Figures 2 and 3). Although his abdominal examination had not changed and did not suggest peritonitis, general surgery was consulted to discuss the need for surgical intervention. Given his overall clinical stability and high surgical risk due to his many comorbidities, surgery recommended a conservative approach.

Through the following hospital days, his enteral nutrition was held and serial abdominal examinations were performed without change. Serial laboratory studies, including serum lactate and leukocyte count, remained reassuringly within normal limits. His urine culture eventually revealed multidrugresistant Pseudomonas aeruginosa. Antimicrobial therapy was narrowed to piperacillintazobactam for a complete course. Enteral nutrition was gradually reintroduced at a low rate, ultimately reaching goal rate with return of bowel function by hospital day 9. Despite extensive workup, the etiology of his transient enteral nutrition intolerance remained uncertain, though an adverse effect of antibiotic therapy was thought possible. Follow-up abdominal radiographs demonstrated interval improvement of PI. He was discharged back to his skilled nursing facility on hospital day 11 without incident.

Discussion

PI is an incompletely understood condition seen in multiple diseases. Patients may present with highly variable symptoms, often more attributable to the underlying disease causing the PI than the presence of PI, as patients may be entirely asymptomatic. When symptoms are attributed to PI, those most reported are abdominal pain, bloody stools, and diarrhea.¹ It is often detected on abdominal plain films. Alternative methods of diagnosis include ultrasonography, barium enema, and endoscopy although the last method has been known to occasionally lead to bowel perforation.^2-6 The most sensitive method of detection is CT, which also provides additional information about abdominal pathology and may identify the underlying process responsible for the PI.⁷

While not fully understood, much information about PI and its pathogenesis is known. Understanding the mechanisms of PI is vital to direct the clinician’s evaluation of the patient for reversible conditions that may cause PI. Early descriptions of PI in the literature documented an association with pyloric stenosis, leading to the theory that gas from the intestinal lumen is driven into the submucosal space during episodes of forceful vomiting with increased intraluminal pressure.⁸ As PI was subsequently described in multiple other disease states not typically associated with increased intraluminal pressure such as inflammatory bowel disease, GI malignancy, cryptosporidiosis and CMV infection, additional theories about the pathogenesis of PI have arisen.^9-24 There is now experimental data to support multiple mechanisms of intramural gas accumulation. It has become accepted that PI represents a common pathway shared across various pathologic states and results from multifactorial mechanisms of gas entry into the intestinal wall.^25-29

Factors leading to the development of PI include bacterial production of gas, intraluminal GI gas compositions, increased intraluminal pressure, pulmonary gas tracking through vessels communicating with the thorax, and mucosal disruption. PI has been linked to bacterial infections of the GI tract in humans including C difficile, Klebsiella, and Whipple disease.^14-18 In animal models, C difficile within the walls of rat intestine results in the appearance of pneumocysts, or discrete collections of submucosal gas, which are the hallmark feature of PI.³⁰ It is thought that direct invasion of bacteria into intramural spaces can cause PI in humans, although bacteria have yet to be directly isolated from the pneumocysts. Translocation of luminal gas into pneumocysts found in PI is theorized to be driven by differences in partial pressures.³¹ The concentration of hydrogen within the intestinal lumen is high due to bacterial production. Hydrogen, diffusing along its partial pressure gradient between the lumen and blood, accumulates within the intestinal wall and causes the formation of pneumocysts. This phenomenon has been hypothesized to explain the tendency for pneumocysts to form around the mesenteric vasculature.

Gas from the lumen can also be forced into the intestinal wall during an abrupt increase in intra-abdominal pressure, such as that seen with forceful vomiting. The final possible origin of the gas is the lungs, as PI has been associated with lung disease. It was previously thought that gas from ruptured alveoli tracks along mediastinal vessels, below the diaphragm, and into the mesentery.³⁰ Newer theories argue that increased intra-abdominal pressure, typical of patients with obstructive lung disease and frequent coughing, is the driver of PI by the mechanism previously described.^32-34 Additionally, mucosal disruption leads to increased permeability and allows accumulation of gas within the intestinal walls. Mucosal abnormalities have been described in histopathologic studies of patients with PI and associated with conditions known to compromise mucosal integrity, such as immunodeficiencies, inflammatory bowel disease, and the receipt of cytotoxic chemotherapy.^10,12,19-23

Our patient likely had mucosal disruption due to his gastrostomy tube as well as increased intraluminal pressure from recurrent vomiting, contributing to translocation of otherwise normal intraluminal gas. The presence of portal venous gas, as seen in this case, has historically portended a worse prognosis, with 37% mortality in one series.^7,35,36 However, portal venous gas as well as pneumoperitoneum occur in benign etiologies of PI as well. It is thought that this occurs due to rupture of the submucosal pneumocysts through the wall opposite the intestinal lumen and thus does not result in a direct communication between the intestinal lumen and the peritoneal cavity.¹²

PI is not a diagnosis but a manifestation of an underlying disease. As such, the treatment of PI is targeted toward the underlying condition. Of note, the pattern and extent of PI seen on imaging has not been shown to correlate with the severity of the underlying pathologic process.^35,37 Instead, assessment of the patient and their clinical trajectory should determine the appropriate treatment. The decision facing the clinician when PI is discovered is whether urgent surgery is indicated, as is the case in mesenteric ischemia, bowel necrosis, or intestinal perforation, conditions known to be associated with PI. Otherwise, there is no definitive treatment for PI. Bowel rest is almost universally pursued. There are reports of treating with supranormal levels of supplemental oxygen, maintaining arterial partial pressure of oxygen above 300 mm Hg, with a face mask and 8 L/min flow rate.^38,39 The proposed mechanisms of benefit include establishing a favorable diffusion gradient for intramural gas to exit the pneumocysts as well as creating an inhospitable, aerobic environment for hydrogenproducing anaerobic enteric bacteria. A prudent approach for most cases of PI is conservative management with bowel rest and supplemental oxygen unless there is a definitive indication for urgent surgical intervention, such as peritonitis, abdominal sepsis, or perforation.^40,41 Management recommendations suggest that up to 50% of cases can be successfully managed nonoperatively.⁴²

Conclusions

PI is the radiographic finding of gas within the walls of the intestinal tract and has variable clinical significance. It can represent a benign incidental finding or a sequela of intraabdominal emergencies such as mesenteric ischemia or bowel necrosis. Because PI is seen in a variety of disorders, several proposed mechanisms are supported in the medical literature. These include bacterial production of gas, gas pressure gradients between the intestinal lumen and the blood, increased intraluminal pressure, pulmonary gas tracking from intrathoracic vessels, and mucosal disruption. The evaluation of a patient with PI must begin with an assessment for the need for urgent surgical intervention. Additional management measures include bowel rest, IV hydration, and supplemental oxygen administration. Because of its wide variety of etiologies of varying clinical urgency, placing the finding of PI in the context of the patient is paramount to selecting an appropriate management strategy.

Pneumatosis intestinalis (PI) is the finding of gas within the walls of the intestine on imaging. It is most commonly detected via radiograph or computed tomography (CT). The diseases leading to the accumulation of gas within the submucosal space of the gastrointestinal (GI) tract are heterogenous, and the finding of PI itself has a wide range of clinical implications from impending clinical deterioration to an incidental finding of minimal consequence.

We present the case of a veteran who had sustained a remote anoxic brain injury resulting in chronic dependence on a gastrostomy tube for enteral nutrition, found incidentally to have PI without signs of intra-abdominal catastrophe. An exclusion of other, more lifethreatening causes of PI led to a diagnosis of benign PI secondary to the presence of his gastrostomy tube. This case highlights the importance of interpreting the finding of PI in the clinical context of the specific patient and how conservative management may be appropriate in some cases.

Case Presentation

A 61-year-old male patient was admitted for fever. The patient had a remote history of cardiac arrest complicated by anoxic brain injury requiring tracheostomy, gastrostomy tube, and a suprapubic catheter with recurrent catheter-associated urinary tract infections (CAUTI), secondary seizure disorder, atrial fibrillation off anticoagulation due to recurrent GI bleeding, and treatment naive chronic hepatitis C virus. His ability to provide a clinical history was limited by his nonverbal status. He had no prior surgical history but had presented a month earlier for a high-grade small bowel obstruction (SBO) with pneumobilia that was managed conservatively as the surgical team deemed him a poor candidate for surgical intervention with his extensive comorbidities. A bioethics consultation at the time supported minimizing potential surgical risk in favor of conservative medical management; this was discussed with the patient’s surrogate decision maker, who also wished to avoid surgery. The SBO resolved with conservative management. He had been residing in a nursing home and doing well until 24 hours prior to admission when he developed fevers.

Vital signs on admission showed a temperature of 100.8 °F, heart rate 100 beats per minute, blood pressure 116/85, respiratory rate 22 per minute, and oxygen saturation of 100% on 6 L of oxygen via tracheostomy collar. His initial examination was notable for clear lung sounds, a nondistended nonrigid abdomen with an indwelling percutaneous gastrostomy tube, and absence of areas of skin breakdown or erythema. Notable laboratory studies showed a leukocytosis and urinalysis suggestive of CAUTI (Table). His urinary catheter was exchanged, he was fluid resuscitated and started on empiric vancomycin and piperacillin-tazobactam for management of sepsis due to CAUTI.

For the first 3 days of his hospitalization, he demonstrated clinical improvement on vancomycin and piperacillin-tazobactam while awaiting results from his urine bacterial culture. On hospital day 3, hedeveloped recurrent nonbloody, nonbilious emesis despite no change in the rate or formulation of his enteral nutrition. He also had 3 watery brown bowel movements. His vital signs remained within normal limits. His abdominal examination at this point showed mild distention and was hypertympanic to percussion, but there was no rigidity or involuntary guarding. On hospital day 4, he continued to have emesis with an unchanged abdominal examination. The differential diagnosis included recurrence of prior SBO, ileus, intestinal ischemia, enteral nutrition intolerance, Clostridioides difficile (C difficile) colitis, and GI dysmotility because of his anoxic brain injury.

Testing for C difficile was negative. An abdominal radiograph was obtained and revealed no bowel obstruction but, alarmingly, showed extensive intramural bowel gas, suggestive of PI (Figure 1). His leukocyte count, serum bicarbonate, and serum lactate levels remained within normal limits. A CT with contrast of the abdomen and pelvis demonstrated no vascular obstruction but confirmed the presence of diffuse intramural gas in his stomach and proximal small bowel, as well as the presence of mesenteric and portal venous gas (Figures 2 and 3). Although his abdominal examination had not changed and did not suggest peritonitis, general surgery was consulted to discuss the need for surgical intervention. Given his overall clinical stability and high surgical risk due to his many comorbidities, surgery recommended a conservative approach.

Through the following hospital days, his enteral nutrition was held and serial abdominal examinations were performed without change. Serial laboratory studies, including serum lactate and leukocyte count, remained reassuringly within normal limits. His urine culture eventually revealed multidrugresistant Pseudomonas aeruginosa. Antimicrobial therapy was narrowed to piperacillintazobactam for a complete course. Enteral nutrition was gradually reintroduced at a low rate, ultimately reaching goal rate with return of bowel function by hospital day 9. Despite extensive workup, the etiology of his transient enteral nutrition intolerance remained uncertain, though an adverse effect of antibiotic therapy was thought possible. Follow-up abdominal radiographs demonstrated interval improvement of PI. He was discharged back to his skilled nursing facility on hospital day 11 without incident.

Discussion

PI is an incompletely understood condition seen in multiple diseases. Patients may present with highly variable symptoms, often more attributable to the underlying disease causing the PI than the presence of PI, as patients may be entirely asymptomatic. When symptoms are attributed to PI, those most reported are abdominal pain, bloody stools, and diarrhea.¹ It is often detected on abdominal plain films. Alternative methods of diagnosis include ultrasonography, barium enema, and endoscopy although the last method has been known to occasionally lead to bowel perforation.^2-6 The most sensitive method of detection is CT, which also provides additional information about abdominal pathology and may identify the underlying process responsible for the PI.⁷

While not fully understood, much information about PI and its pathogenesis is known. Understanding the mechanisms of PI is vital to direct the clinician’s evaluation of the patient for reversible conditions that may cause PI. Early descriptions of PI in the literature documented an association with pyloric stenosis, leading to the theory that gas from the intestinal lumen is driven into the submucosal space during episodes of forceful vomiting with increased intraluminal pressure.⁸ As PI was subsequently described in multiple other disease states not typically associated with increased intraluminal pressure such as inflammatory bowel disease, GI malignancy, cryptosporidiosis and CMV infection, additional theories about the pathogenesis of PI have arisen.^9-24 There is now experimental data to support multiple mechanisms of intramural gas accumulation. It has become accepted that PI represents a common pathway shared across various pathologic states and results from multifactorial mechanisms of gas entry into the intestinal wall.^25-29

Factors leading to the development of PI include bacterial production of gas, intraluminal GI gas compositions, increased intraluminal pressure, pulmonary gas tracking through vessels communicating with the thorax, and mucosal disruption. PI has been linked to bacterial infections of the GI tract in humans including C difficile, Klebsiella, and Whipple disease.^14-18 In animal models, C difficile within the walls of rat intestine results in the appearance of pneumocysts, or discrete collections of submucosal gas, which are the hallmark feature of PI.³⁰ It is thought that direct invasion of bacteria into intramural spaces can cause PI in humans, although bacteria have yet to be directly isolated from the pneumocysts. Translocation of luminal gas into pneumocysts found in PI is theorized to be driven by differences in partial pressures.³¹ The concentration of hydrogen within the intestinal lumen is high due to bacterial production. Hydrogen, diffusing along its partial pressure gradient between the lumen and blood, accumulates within the intestinal wall and causes the formation of pneumocysts. This phenomenon has been hypothesized to explain the tendency for pneumocysts to form around the mesenteric vasculature.

Gas from the lumen can also be forced into the intestinal wall during an abrupt increase in intra-abdominal pressure, such as that seen with forceful vomiting. The final possible origin of the gas is the lungs, as PI has been associated with lung disease. It was previously thought that gas from ruptured alveoli tracks along mediastinal vessels, below the diaphragm, and into the mesentery.³⁰ Newer theories argue that increased intra-abdominal pressure, typical of patients with obstructive lung disease and frequent coughing, is the driver of PI by the mechanism previously described.^32-34 Additionally, mucosal disruption leads to increased permeability and allows accumulation of gas within the intestinal walls. Mucosal abnormalities have been described in histopathologic studies of patients with PI and associated with conditions known to compromise mucosal integrity, such as immunodeficiencies, inflammatory bowel disease, and the receipt of cytotoxic chemotherapy.^10,12,19-23

Our patient likely had mucosal disruption due to his gastrostomy tube as well as increased intraluminal pressure from recurrent vomiting, contributing to translocation of otherwise normal intraluminal gas. The presence of portal venous gas, as seen in this case, has historically portended a worse prognosis, with 37% mortality in one series.^7,35,36 However, portal venous gas as well as pneumoperitoneum occur in benign etiologies of PI as well. It is thought that this occurs due to rupture of the submucosal pneumocysts through the wall opposite the intestinal lumen and thus does not result in a direct communication between the intestinal lumen and the peritoneal cavity.¹²

PI is not a diagnosis but a manifestation of an underlying disease. As such, the treatment of PI is targeted toward the underlying condition. Of note, the pattern and extent of PI seen on imaging has not been shown to correlate with the severity of the underlying pathologic process.^35,37 Instead, assessment of the patient and their clinical trajectory should determine the appropriate treatment. The decision facing the clinician when PI is discovered is whether urgent surgery is indicated, as is the case in mesenteric ischemia, bowel necrosis, or intestinal perforation, conditions known to be associated with PI. Otherwise, there is no definitive treatment for PI. Bowel rest is almost universally pursued. There are reports of treating with supranormal levels of supplemental oxygen, maintaining arterial partial pressure of oxygen above 300 mm Hg, with a face mask and 8 L/min flow rate.^38,39 The proposed mechanisms of benefit include establishing a favorable diffusion gradient for intramural gas to exit the pneumocysts as well as creating an inhospitable, aerobic environment for hydrogenproducing anaerobic enteric bacteria. A prudent approach for most cases of PI is conservative management with bowel rest and supplemental oxygen unless there is a definitive indication for urgent surgical intervention, such as peritonitis, abdominal sepsis, or perforation.^40,41 Management recommendations suggest that up to 50% of cases can be successfully managed nonoperatively.⁴²

Conclusions

PI is the radiographic finding of gas within the walls of the intestinal tract and has variable clinical significance. It can represent a benign incidental finding or a sequela of intraabdominal emergencies such as mesenteric ischemia or bowel necrosis. Because PI is seen in a variety of disorders, several proposed mechanisms are supported in the medical literature. These include bacterial production of gas, gas pressure gradients between the intestinal lumen and the blood, increased intraluminal pressure, pulmonary gas tracking from intrathoracic vessels, and mucosal disruption. The evaluation of a patient with PI must begin with an assessment for the need for urgent surgical intervention. Additional management measures include bowel rest, IV hydration, and supplemental oxygen administration. Because of its wide variety of etiologies of varying clinical urgency, placing the finding of PI in the context of the patient is paramount to selecting an appropriate management strategy.

Pneumatosis intestinalis (PI) is the finding of gas within the walls of the intestine on imaging. It is most commonly detected via radiograph or computed tomography (CT). The diseases leading to the accumulation of gas within the submucosal space of the gastrointestinal (GI) tract are heterogenous, and the finding of PI itself has a wide range of clinical implications from impending clinical deterioration to an incidental finding of minimal consequence.

We present the case of a veteran who had sustained a remote anoxic brain injury resulting in chronic dependence on a gastrostomy tube for enteral nutrition, found incidentally to have PI without signs of intra-abdominal catastrophe. An exclusion of other, more lifethreatening causes of PI led to a diagnosis of benign PI secondary to the presence of his gastrostomy tube. This case highlights the importance of interpreting the finding of PI in the clinical context of the specific patient and how conservative management may be appropriate in some cases.

Case Presentation

A 61-year-old male patient was admitted for fever. The patient had a remote history of cardiac arrest complicated by anoxic brain injury requiring tracheostomy, gastrostomy tube, and a suprapubic catheter with recurrent catheter-associated urinary tract infections (CAUTI), secondary seizure disorder, atrial fibrillation off anticoagulation due to recurrent GI bleeding, and treatment naive chronic hepatitis C virus. His ability to provide a clinical history was limited by his nonverbal status. He had no prior surgical history but had presented a month earlier for a high-grade small bowel obstruction (SBO) with pneumobilia that was managed conservatively as the surgical team deemed him a poor candidate for surgical intervention with his extensive comorbidities. A bioethics consultation at the time supported minimizing potential surgical risk in favor of conservative medical management; this was discussed with the patient’s surrogate decision maker, who also wished to avoid surgery. The SBO resolved with conservative management. He had been residing in a nursing home and doing well until 24 hours prior to admission when he developed fevers.

Vital signs on admission showed a temperature of 100.8 °F, heart rate 100 beats per minute, blood pressure 116/85, respiratory rate 22 per minute, and oxygen saturation of 100% on 6 L of oxygen via tracheostomy collar. His initial examination was notable for clear lung sounds, a nondistended nonrigid abdomen with an indwelling percutaneous gastrostomy tube, and absence of areas of skin breakdown or erythema. Notable laboratory studies showed a leukocytosis and urinalysis suggestive of CAUTI (Table). His urinary catheter was exchanged, he was fluid resuscitated and started on empiric vancomycin and piperacillin-tazobactam for management of sepsis due to CAUTI.

For the first 3 days of his hospitalization, he demonstrated clinical improvement on vancomycin and piperacillin-tazobactam while awaiting results from his urine bacterial culture. On hospital day 3, hedeveloped recurrent nonbloody, nonbilious emesis despite no change in the rate or formulation of his enteral nutrition. He also had 3 watery brown bowel movements. His vital signs remained within normal limits. His abdominal examination at this point showed mild distention and was hypertympanic to percussion, but there was no rigidity or involuntary guarding. On hospital day 4, he continued to have emesis with an unchanged abdominal examination. The differential diagnosis included recurrence of prior SBO, ileus, intestinal ischemia, enteral nutrition intolerance, Clostridioides difficile (C difficile) colitis, and GI dysmotility because of his anoxic brain injury.

Testing for C difficile was negative. An abdominal radiograph was obtained and revealed no bowel obstruction but, alarmingly, showed extensive intramural bowel gas, suggestive of PI (Figure 1). His leukocyte count, serum bicarbonate, and serum lactate levels remained within normal limits. A CT with contrast of the abdomen and pelvis demonstrated no vascular obstruction but confirmed the presence of diffuse intramural gas in his stomach and proximal small bowel, as well as the presence of mesenteric and portal venous gas (Figures 2 and 3). Although his abdominal examination had not changed and did not suggest peritonitis, general surgery was consulted to discuss the need for surgical intervention. Given his overall clinical stability and high surgical risk due to his many comorbidities, surgery recommended a conservative approach.

Through the following hospital days, his enteral nutrition was held and serial abdominal examinations were performed without change. Serial laboratory studies, including serum lactate and leukocyte count, remained reassuringly within normal limits. His urine culture eventually revealed multidrugresistant Pseudomonas aeruginosa. Antimicrobial therapy was narrowed to piperacillintazobactam for a complete course. Enteral nutrition was gradually reintroduced at a low rate, ultimately reaching goal rate with return of bowel function by hospital day 9. Despite extensive workup, the etiology of his transient enteral nutrition intolerance remained uncertain, though an adverse effect of antibiotic therapy was thought possible. Follow-up abdominal radiographs demonstrated interval improvement of PI. He was discharged back to his skilled nursing facility on hospital day 11 without incident.

Discussion

PI is an incompletely understood condition seen in multiple diseases. Patients may present with highly variable symptoms, often more attributable to the underlying disease causing the PI than the presence of PI, as patients may be entirely asymptomatic. When symptoms are attributed to PI, those most reported are abdominal pain, bloody stools, and diarrhea.¹ It is often detected on abdominal plain films. Alternative methods of diagnosis include ultrasonography, barium enema, and endoscopy although the last method has been known to occasionally lead to bowel perforation.^2-6 The most sensitive method of detection is CT, which also provides additional information about abdominal pathology and may identify the underlying process responsible for the PI.⁷

While not fully understood, much information about PI and its pathogenesis is known. Understanding the mechanisms of PI is vital to direct the clinician’s evaluation of the patient for reversible conditions that may cause PI. Early descriptions of PI in the literature documented an association with pyloric stenosis, leading to the theory that gas from the intestinal lumen is driven into the submucosal space during episodes of forceful vomiting with increased intraluminal pressure.⁸ As PI was subsequently described in multiple other disease states not typically associated with increased intraluminal pressure such as inflammatory bowel disease, GI malignancy, cryptosporidiosis and CMV infection, additional theories about the pathogenesis of PI have arisen.^9-24 There is now experimental data to support multiple mechanisms of intramural gas accumulation. It has become accepted that PI represents a common pathway shared across various pathologic states and results from multifactorial mechanisms of gas entry into the intestinal wall.^25-29

Factors leading to the development of PI include bacterial production of gas, intraluminal GI gas compositions, increased intraluminal pressure, pulmonary gas tracking through vessels communicating with the thorax, and mucosal disruption. PI has been linked to bacterial infections of the GI tract in humans including C difficile, Klebsiella, and Whipple disease.^14-18 In animal models, C difficile within the walls of rat intestine results in the appearance of pneumocysts, or discrete collections of submucosal gas, which are the hallmark feature of PI.³⁰ It is thought that direct invasion of bacteria into intramural spaces can cause PI in humans, although bacteria have yet to be directly isolated from the pneumocysts. Translocation of luminal gas into pneumocysts found in PI is theorized to be driven by differences in partial pressures.³¹ The concentration of hydrogen within the intestinal lumen is high due to bacterial production. Hydrogen, diffusing along its partial pressure gradient between the lumen and blood, accumulates within the intestinal wall and causes the formation of pneumocysts. This phenomenon has been hypothesized to explain the tendency for pneumocysts to form around the mesenteric vasculature.

Gas from the lumen can also be forced into the intestinal wall during an abrupt increase in intra-abdominal pressure, such as that seen with forceful vomiting. The final possible origin of the gas is the lungs, as PI has been associated with lung disease. It was previously thought that gas from ruptured alveoli tracks along mediastinal vessels, below the diaphragm, and into the mesentery.³⁰ Newer theories argue that increased intra-abdominal pressure, typical of patients with obstructive lung disease and frequent coughing, is the driver of PI by the mechanism previously described.^32-34 Additionally, mucosal disruption leads to increased permeability and allows accumulation of gas within the intestinal walls. Mucosal abnormalities have been described in histopathologic studies of patients with PI and associated with conditions known to compromise mucosal integrity, such as immunodeficiencies, inflammatory bowel disease, and the receipt of cytotoxic chemotherapy.^10,12,19-23

Our patient likely had mucosal disruption due to his gastrostomy tube as well as increased intraluminal pressure from recurrent vomiting, contributing to translocation of otherwise normal intraluminal gas. The presence of portal venous gas, as seen in this case, has historically portended a worse prognosis, with 37% mortality in one series.^7,35,36 However, portal venous gas as well as pneumoperitoneum occur in benign etiologies of PI as well. It is thought that this occurs due to rupture of the submucosal pneumocysts through the wall opposite the intestinal lumen and thus does not result in a direct communication between the intestinal lumen and the peritoneal cavity.¹²

PI is not a diagnosis but a manifestation of an underlying disease. As such, the treatment of PI is targeted toward the underlying condition. Of note, the pattern and extent of PI seen on imaging has not been shown to correlate with the severity of the underlying pathologic process.^35,37 Instead, assessment of the patient and their clinical trajectory should determine the appropriate treatment. The decision facing the clinician when PI is discovered is whether urgent surgery is indicated, as is the case in mesenteric ischemia, bowel necrosis, or intestinal perforation, conditions known to be associated with PI. Otherwise, there is no definitive treatment for PI. Bowel rest is almost universally pursued. There are reports of treating with supranormal levels of supplemental oxygen, maintaining arterial partial pressure of oxygen above 300 mm Hg, with a face mask and 8 L/min flow rate.^38,39 The proposed mechanisms of benefit include establishing a favorable diffusion gradient for intramural gas to exit the pneumocysts as well as creating an inhospitable, aerobic environment for hydrogenproducing anaerobic enteric bacteria. A prudent approach for most cases of PI is conservative management with bowel rest and supplemental oxygen unless there is a definitive indication for urgent surgical intervention, such as peritonitis, abdominal sepsis, or perforation.^40,41 Management recommendations suggest that up to 50% of cases can be successfully managed nonoperatively.⁴²

Conclusions

PI is the radiographic finding of gas within the walls of the intestinal tract and has variable clinical significance. It can represent a benign incidental finding or a sequela of intraabdominal emergencies such as mesenteric ischemia or bowel necrosis. Because PI is seen in a variety of disorders, several proposed mechanisms are supported in the medical literature. These include bacterial production of gas, gas pressure gradients between the intestinal lumen and the blood, increased intraluminal pressure, pulmonary gas tracking from intrathoracic vessels, and mucosal disruption. The evaluation of a patient with PI must begin with an assessment for the need for urgent surgical intervention. Additional management measures include bowel rest, IV hydration, and supplemental oxygen administration. Because of its wide variety of etiologies of varying clinical urgency, placing the finding of PI in the context of the patient is paramount to selecting an appropriate management strategy.

THE CASE

A 62-year-old postmenopausal woman presented to the clinic as a new patient for her annual physical examination. She reported a 9-year history of symptoms including dysuria, post-void dribbling, dyspareunia, and urinary incontinence on review of systems. Her physical examination revealed an anterior vaginal wall bulge (FIGURE). Results of a urinalysis were negative. The patient was referred to Urology for further evaluation.

THE DIAGNOSIS

A pelvic magnetic resonance imaging (MRI) scan revealed a large periurethral diverticulum with a horseshoe shape.

DISCUSSION

Urethral diverticulum is a permanent sac-like cavity projecting into the periurethral fascia arising from the posterior urethral lumen.¹ It is a rare condition that affects fewer than 20 per 1 million women per year.² Urethral diverticulum can range from 1 cm to 8 cm in diameter and is located in the mid or distal urethra.^1,3

Women are more likely than men to develop urethral diverticulum, and it can manifest at any age, usually in the third through seventh decade.^4,5 It was once thought to be more common in Black women, although the literature does not support this.⁶ Black women are 3 times more likely to be operated on than White women to treat urethral diverticula.⁷

Unknown origin. Most cases of urethral diverticulum are acquired; the etiology is uncertain.^8,9 The assumption is that urethral diverticulum occurs as a result of repeated infection of the periurethral glands with subsequent obstruction, abscess formation, and chronic inflammation.^1,2,4 Childbirth trauma, iatrogenic causes, and urethral instrumentation have also been implicated.^3,4 In rare cases of congenital urethral diverticula, the diverticula are thought to be remnants of Gartner duct cysts, and yet, incidence in the pediatric population is low.⁸

Diagnosis is confirmed through physical exam and imaging

The urethral diverticulum manifests anteriorly and palpation of the anterior vaginal wall may reveal a painful mass.¹⁰ A split-speculum is used for careful inspection and palpation of the anterior vaginal wall.⁹ If the diverticulum is found to be firm on palpation, or there is bloody urethral drainage, malignancy (although rare) must be ruled out.^4,5 Refer such patients to a urologist or urogynecologist.

The MRI, with or without endoluminal coil, is considered the gold standard in diagnosing urethral diverticulum.

Radiologic imaging (eg, ultrasound, voiding cystourethrography [VCUG], and MRI) is useful in detecting the size, location, and extent of the diverticulum, revealing the relationship to surrounding tissues, and providing insights for appropriate surgical management.^3,4,9 Ultrasound, which is usually readily available, noninvasive, and less expensive, can be considered for initial screening of suspected urethral diverticulum.^3,11 A postvoid MRI is recommended when a urethral diverticulum is highly suspected.^11,12 The MRI, with or without endoluminal coil, is considered the gold standard; it is a favorable complement to the work-up and offers the most diagnostic value.^3,4 According to a single-institution study, the MRI was 100% sensitive and specific in diagnosing urethral diverticulum.¹² However, the limitation of the MRI lies in its cost and lack of availability in some countries.¹³

Continue to: Nonspecific symptoms may lead to misdiagnosis

Nonspecific symptoms may lead to misdiagnosis. The symptoms associated with urethral diverticulum are diverse and linked to several differential diagnoses (TABLE).^3,4,12 The most common signs and symptoms are pelvic pain, urethral mass, dyspareunia, dysuria, urinary incontinence, and post-void dribbling—all of which are considered nonspecific.^3,10,11 These nonspecific symptoms (or even an absence of symptoms), along with a physician’s lack of familiarity with urethral diverticulum, can result in a misdiagnosis or even a delayed diagnosis (up to 5.2 years).^3,10

Managing symptoms vs preventing recurrence

Conservative management with antibiotics, anticholinergics, and/or observation is acceptable for patients with mild symptoms and those who are pregnant or who have a current infection or serious comorbidities that preclude surgery.^3,9 Complete excision of the urethral diverticulum with reconstruction is considered the most effective surgical management for symptom relief and recurrence prevention.^3,4,11,14

Our patient underwent a successful transvaginal suburethral diverticulectomy.

THE TAKEAWAY

The diagnosis of female urethral diverticulum is often delayed or misdiagnosed because symptoms are diverse and nonspecific. One should have a high degree of suspicion for urethral diverticulum in patients with dysuria, dyspareunia, pelvic pain, urinary incontinence, and irritative voiding symptoms who are not responding to conservative management. Ultrasound is an appropriate first-line imaging modality. However, a pelvic MRI is the most sensitive and specific in diagnosing urethral diverticulum.¹²

CORRESPONDENCE
Folashade Omole, MD, FAAFP, 720 Westview Drive, Atlanta, GA 30310; [email protected]

THE CASE

A 62-year-old postmenopausal woman presented to the clinic as a new patient for her annual physical examination. She reported a 9-year history of symptoms including dysuria, post-void dribbling, dyspareunia, and urinary incontinence on review of systems. Her physical examination revealed an anterior vaginal wall bulge (FIGURE). Results of a urinalysis were negative. The patient was referred to Urology for further evaluation.

THE DIAGNOSIS

A pelvic magnetic resonance imaging (MRI) scan revealed a large periurethral diverticulum with a horseshoe shape.

DISCUSSION

Urethral diverticulum is a permanent sac-like cavity projecting into the periurethral fascia arising from the posterior urethral lumen.¹ It is a rare condition that affects fewer than 20 per 1 million women per year.² Urethral diverticulum can range from 1 cm to 8 cm in diameter and is located in the mid or distal urethra.^1,3

Women are more likely than men to develop urethral diverticulum, and it can manifest at any age, usually in the third through seventh decade.^4,5 It was once thought to be more common in Black women, although the literature does not support this.⁶ Black women are 3 times more likely to be operated on than White women to treat urethral diverticula.⁷

Unknown origin. Most cases of urethral diverticulum are acquired; the etiology is uncertain.^8,9 The assumption is that urethral diverticulum occurs as a result of repeated infection of the periurethral glands with subsequent obstruction, abscess formation, and chronic inflammation.^1,2,4 Childbirth trauma, iatrogenic causes, and urethral instrumentation have also been implicated.^3,4 In rare cases of congenital urethral diverticula, the diverticula are thought to be remnants of Gartner duct cysts, and yet, incidence in the pediatric population is low.⁸

Diagnosis is confirmed through physical exam and imaging

The urethral diverticulum manifests anteriorly and palpation of the anterior vaginal wall may reveal a painful mass.¹⁰ A split-speculum is used for careful inspection and palpation of the anterior vaginal wall.⁹ If the diverticulum is found to be firm on palpation, or there is bloody urethral drainage, malignancy (although rare) must be ruled out.^4,5 Refer such patients to a urologist or urogynecologist.

The MRI, with or without endoluminal coil, is considered the gold standard in diagnosing urethral diverticulum.

Radiologic imaging (eg, ultrasound, voiding cystourethrography [VCUG], and MRI) is useful in detecting the size, location, and extent of the diverticulum, revealing the relationship to surrounding tissues, and providing insights for appropriate surgical management.^3,4,9 Ultrasound, which is usually readily available, noninvasive, and less expensive, can be considered for initial screening of suspected urethral diverticulum.^3,11 A postvoid MRI is recommended when a urethral diverticulum is highly suspected.^11,12 The MRI, with or without endoluminal coil, is considered the gold standard; it is a favorable complement to the work-up and offers the most diagnostic value.^3,4 According to a single-institution study, the MRI was 100% sensitive and specific in diagnosing urethral diverticulum.¹² However, the limitation of the MRI lies in its cost and lack of availability in some countries.¹³

Continue to: Nonspecific symptoms may lead to misdiagnosis

Nonspecific symptoms may lead to misdiagnosis. The symptoms associated with urethral diverticulum are diverse and linked to several differential diagnoses (TABLE).^3,4,12 The most common signs and symptoms are pelvic pain, urethral mass, dyspareunia, dysuria, urinary incontinence, and post-void dribbling—all of which are considered nonspecific.^3,10,11 These nonspecific symptoms (or even an absence of symptoms), along with a physician’s lack of familiarity with urethral diverticulum, can result in a misdiagnosis or even a delayed diagnosis (up to 5.2 years).^3,10

Managing symptoms vs preventing recurrence

Conservative management with antibiotics, anticholinergics, and/or observation is acceptable for patients with mild symptoms and those who are pregnant or who have a current infection or serious comorbidities that preclude surgery.^3,9 Complete excision of the urethral diverticulum with reconstruction is considered the most effective surgical management for symptom relief and recurrence prevention.^3,4,11,14

Our patient underwent a successful transvaginal suburethral diverticulectomy.

THE TAKEAWAY

The diagnosis of female urethral diverticulum is often delayed or misdiagnosed because symptoms are diverse and nonspecific. One should have a high degree of suspicion for urethral diverticulum in patients with dysuria, dyspareunia, pelvic pain, urinary incontinence, and irritative voiding symptoms who are not responding to conservative management. Ultrasound is an appropriate first-line imaging modality. However, a pelvic MRI is the most sensitive and specific in diagnosing urethral diverticulum.¹²

CORRESPONDENCE
Folashade Omole, MD, FAAFP, 720 Westview Drive, Atlanta, GA 30310; [email protected]

THE CASE

A 62-year-old postmenopausal woman presented to the clinic as a new patient for her annual physical examination. She reported a 9-year history of symptoms including dysuria, post-void dribbling, dyspareunia, and urinary incontinence on review of systems. Her physical examination revealed an anterior vaginal wall bulge (FIGURE). Results of a urinalysis were negative. The patient was referred to Urology for further evaluation.

THE DIAGNOSIS

A pelvic magnetic resonance imaging (MRI) scan revealed a large periurethral diverticulum with a horseshoe shape.

DISCUSSION

Urethral diverticulum is a permanent sac-like cavity projecting into the periurethral fascia arising from the posterior urethral lumen.¹ It is a rare condition that affects fewer than 20 per 1 million women per year.² Urethral diverticulum can range from 1 cm to 8 cm in diameter and is located in the mid or distal urethra.^1,3

Women are more likely than men to develop urethral diverticulum, and it can manifest at any age, usually in the third through seventh decade.^4,5 It was once thought to be more common in Black women, although the literature does not support this.⁶ Black women are 3 times more likely to be operated on than White women to treat urethral diverticula.⁷

Unknown origin. Most cases of urethral diverticulum are acquired; the etiology is uncertain.^8,9 The assumption is that urethral diverticulum occurs as a result of repeated infection of the periurethral glands with subsequent obstruction, abscess formation, and chronic inflammation.^1,2,4 Childbirth trauma, iatrogenic causes, and urethral instrumentation have also been implicated.^3,4 In rare cases of congenital urethral diverticula, the diverticula are thought to be remnants of Gartner duct cysts, and yet, incidence in the pediatric population is low.⁸

Diagnosis is confirmed through physical exam and imaging

The urethral diverticulum manifests anteriorly and palpation of the anterior vaginal wall may reveal a painful mass.¹⁰ A split-speculum is used for careful inspection and palpation of the anterior vaginal wall.⁹ If the diverticulum is found to be firm on palpation, or there is bloody urethral drainage, malignancy (although rare) must be ruled out.^4,5 Refer such patients to a urologist or urogynecologist.

The MRI, with or without endoluminal coil, is considered the gold standard in diagnosing urethral diverticulum.

Radiologic imaging (eg, ultrasound, voiding cystourethrography [VCUG], and MRI) is useful in detecting the size, location, and extent of the diverticulum, revealing the relationship to surrounding tissues, and providing insights for appropriate surgical management.^3,4,9 Ultrasound, which is usually readily available, noninvasive, and less expensive, can be considered for initial screening of suspected urethral diverticulum.^3,11 A postvoid MRI is recommended when a urethral diverticulum is highly suspected.^11,12 The MRI, with or without endoluminal coil, is considered the gold standard; it is a favorable complement to the work-up and offers the most diagnostic value.^3,4 According to a single-institution study, the MRI was 100% sensitive and specific in diagnosing urethral diverticulum.¹² However, the limitation of the MRI lies in its cost and lack of availability in some countries.¹³

Continue to: Nonspecific symptoms may lead to misdiagnosis

Nonspecific symptoms may lead to misdiagnosis. The symptoms associated with urethral diverticulum are diverse and linked to several differential diagnoses (TABLE).^3,4,12 The most common signs and symptoms are pelvic pain, urethral mass, dyspareunia, dysuria, urinary incontinence, and post-void dribbling—all of which are considered nonspecific.^3,10,11 These nonspecific symptoms (or even an absence of symptoms), along with a physician’s lack of familiarity with urethral diverticulum, can result in a misdiagnosis or even a delayed diagnosis (up to 5.2 years).^3,10

Managing symptoms vs preventing recurrence

Conservative management with antibiotics, anticholinergics, and/or observation is acceptable for patients with mild symptoms and those who are pregnant or who have a current infection or serious comorbidities that preclude surgery.^3,9 Complete excision of the urethral diverticulum with reconstruction is considered the most effective surgical management for symptom relief and recurrence prevention.^3,4,11,14

Our patient underwent a successful transvaginal suburethral diverticulectomy.

THE TAKEAWAY

The diagnosis of female urethral diverticulum is often delayed or misdiagnosed because symptoms are diverse and nonspecific. One should have a high degree of suspicion for urethral diverticulum in patients with dysuria, dyspareunia, pelvic pain, urinary incontinence, and irritative voiding symptoms who are not responding to conservative management. Ultrasound is an appropriate first-line imaging modality. However, a pelvic MRI is the most sensitive and specific in diagnosing urethral diverticulum.¹²

CORRESPONDENCE
Folashade Omole, MD, FAAFP, 720 Westview Drive, Atlanta, GA 30310; [email protected]