Dermatopathology

CHICAGO – The future looks bright for reflectance confocal microscopy (RCM) as a tie breaker to decide whether skin lesions that are equivocal on dermoscopy warrant biopsy to rule out malignancy, Ann M. John, MD, asserted at the annual meeting of the American College of Mohs Surgery.

“With the advent of dermoscopy, dermatologists were able to elucidate both benign and malignant patterns to help further guide their decision to biopsy or not. This increased diagnostic accuracy of suspicious lesions by 30%, while reducing the benign to malignant ratio of biopsies performed from 18:1 to 4:1. However, there are still lesions that are equivocal on dermoscopy, as we all know, and for this, there’s reflectance confocal microscopy,” observed Dr. John, of Robert Wood Johnson Medical School, New Brunswick, N.J.

RCM is a device technology that’s been cleared by the Food and Drug Administration since 2008 for the imaging of clinically suspicious lesions. It employs laser scanning to assess the light-scattering properties of cells in the epidermis and dermis, generating images with resolution comparable to histology.

RCM took a back seat initially while American dermatologists were gradually coming to embrace dermoscopy, which their European colleagues had done years earlier. Now, with the availability of handheld RCM for use in the dermatology clinic, expect RCM to assume a growing role in daily practice.

To illustrate the power of RCM as a diagnostic aid, she presented a single-center retrospective study of 1,189 clinically suspicious skin lesions that were equivocal on dermoscopy and then assessed using RCM with 1 year of subsequent patient follow-up. Overall, 155 lesions were deemed positive for cancer or atypia by RCM, while 1,034 were determined to be benign. Of those 155, 46 lesions were considered false positives because of their benign appearance on histologic inspection of the biopsy sample. Only 2 of the 1,034 lesions identified as negative by RCM proved to be false negatives on the basis of clinical changes within 1 year.

The overall sensitivity and specificity of RCM was 98.2% and 99.8%, respectively, with a positive predictive value of 70.3% and a negative predictive value of 99.8%.

The entire RCM procedure takes a skilled technician 15-20 minutes per lesion. As a practical matter, other investigators have estimated that RCM results in a cost savings of about $308,000 per million health plan members per year by reducing the need for biopsies (Dermatol Clin. 2016 Oct;34[4]:367-75).

In addition to evaluating clinically suspicious lesions, other situations in which RCM offers practical value include its use directly before the first cut during Mohs surgery in order to determine the margins of atypia; ex vivo imaging of Mohs margins, which has been shown to be comparable with frozen sections in accuracy but takes only one-third of the time; and imaging of biopsied lesions in order to determine the diagnosis relatively quickly, Dr. John noted.

She reported having no financial conflicts regarding her study.

[email protected]

CHICAGO – The future looks bright for reflectance confocal microscopy (RCM) as a tie breaker to decide whether skin lesions that are equivocal on dermoscopy warrant biopsy to rule out malignancy, Ann M. John, MD, asserted at the annual meeting of the American College of Mohs Surgery.

“With the advent of dermoscopy, dermatologists were able to elucidate both benign and malignant patterns to help further guide their decision to biopsy or not. This increased diagnostic accuracy of suspicious lesions by 30%, while reducing the benign to malignant ratio of biopsies performed from 18:1 to 4:1. However, there are still lesions that are equivocal on dermoscopy, as we all know, and for this, there’s reflectance confocal microscopy,” observed Dr. John, of Robert Wood Johnson Medical School, New Brunswick, N.J.

RCM is a device technology that’s been cleared by the Food and Drug Administration since 2008 for the imaging of clinically suspicious lesions. It employs laser scanning to assess the light-scattering properties of cells in the epidermis and dermis, generating images with resolution comparable to histology.

RCM took a back seat initially while American dermatologists were gradually coming to embrace dermoscopy, which their European colleagues had done years earlier. Now, with the availability of handheld RCM for use in the dermatology clinic, expect RCM to assume a growing role in daily practice.

To illustrate the power of RCM as a diagnostic aid, she presented a single-center retrospective study of 1,189 clinically suspicious skin lesions that were equivocal on dermoscopy and then assessed using RCM with 1 year of subsequent patient follow-up. Overall, 155 lesions were deemed positive for cancer or atypia by RCM, while 1,034 were determined to be benign. Of those 155, 46 lesions were considered false positives because of their benign appearance on histologic inspection of the biopsy sample. Only 2 of the 1,034 lesions identified as negative by RCM proved to be false negatives on the basis of clinical changes within 1 year.

The overall sensitivity and specificity of RCM was 98.2% and 99.8%, respectively, with a positive predictive value of 70.3% and a negative predictive value of 99.8%.

The entire RCM procedure takes a skilled technician 15-20 minutes per lesion. As a practical matter, other investigators have estimated that RCM results in a cost savings of about $308,000 per million health plan members per year by reducing the need for biopsies (Dermatol Clin. 2016 Oct;34[4]:367-75).

In addition to evaluating clinically suspicious lesions, other situations in which RCM offers practical value include its use directly before the first cut during Mohs surgery in order to determine the margins of atypia; ex vivo imaging of Mohs margins, which has been shown to be comparable with frozen sections in accuracy but takes only one-third of the time; and imaging of biopsied lesions in order to determine the diagnosis relatively quickly, Dr. John noted.

She reported having no financial conflicts regarding her study.

[email protected]

CHICAGO – The future looks bright for reflectance confocal microscopy (RCM) as a tie breaker to decide whether skin lesions that are equivocal on dermoscopy warrant biopsy to rule out malignancy, Ann M. John, MD, asserted at the annual meeting of the American College of Mohs Surgery.

“With the advent of dermoscopy, dermatologists were able to elucidate both benign and malignant patterns to help further guide their decision to biopsy or not. This increased diagnostic accuracy of suspicious lesions by 30%, while reducing the benign to malignant ratio of biopsies performed from 18:1 to 4:1. However, there are still lesions that are equivocal on dermoscopy, as we all know, and for this, there’s reflectance confocal microscopy,” observed Dr. John, of Robert Wood Johnson Medical School, New Brunswick, N.J.

RCM is a device technology that’s been cleared by the Food and Drug Administration since 2008 for the imaging of clinically suspicious lesions. It employs laser scanning to assess the light-scattering properties of cells in the epidermis and dermis, generating images with resolution comparable to histology.

RCM took a back seat initially while American dermatologists were gradually coming to embrace dermoscopy, which their European colleagues had done years earlier. Now, with the availability of handheld RCM for use in the dermatology clinic, expect RCM to assume a growing role in daily practice.

To illustrate the power of RCM as a diagnostic aid, she presented a single-center retrospective study of 1,189 clinically suspicious skin lesions that were equivocal on dermoscopy and then assessed using RCM with 1 year of subsequent patient follow-up. Overall, 155 lesions were deemed positive for cancer or atypia by RCM, while 1,034 were determined to be benign. Of those 155, 46 lesions were considered false positives because of their benign appearance on histologic inspection of the biopsy sample. Only 2 of the 1,034 lesions identified as negative by RCM proved to be false negatives on the basis of clinical changes within 1 year.

The overall sensitivity and specificity of RCM was 98.2% and 99.8%, respectively, with a positive predictive value of 70.3% and a negative predictive value of 99.8%.

The entire RCM procedure takes a skilled technician 15-20 minutes per lesion. As a practical matter, other investigators have estimated that RCM results in a cost savings of about $308,000 per million health plan members per year by reducing the need for biopsies (Dermatol Clin. 2016 Oct;34[4]:367-75).

In addition to evaluating clinically suspicious lesions, other situations in which RCM offers practical value include its use directly before the first cut during Mohs surgery in order to determine the margins of atypia; ex vivo imaging of Mohs margins, which has been shown to be comparable with frozen sections in accuracy but takes only one-third of the time; and imaging of biopsied lesions in order to determine the diagnosis relatively quickly, Dr. John noted.

She reported having no financial conflicts regarding her study.

[email protected]

In 2010, two separate reports of cutaneous vasculitic/vasculopathic eruptions in patients with recent exposure to levamisole-contaminated cocaine (LCC) were published in the literature.^1,2 Since then, additional reports have been published.^3-6 Retiform purpura associated with cocaine use appears to be a similar condition, perhaps lying at one end of the spectrum of LCC-induced cutaneous vascular disease.^7,8 Although some patients have been described as having nausea and vomiting,^8,9 including one with a sudden drop in hemoglobin to 5.8 g/dL (reference range, 14.0–17.5 g/dL),¹⁰ there are no known reported cases of LCC and levamisole-induced vasculopathy in organ systems other than the skin. Herein, we report the case of a patient with levamisole-induced vasculopathy (LIV) demonstrating endoscopic evidence of gastric hemorrhage with features similar to those involving the skin.

Case Report

A 35-year-old woman with a history of hepatitis C, intravenous drug abuse, and bipolar disorder presented to the emergency department with painful necrotic lesions on the head, neck, arms, and legs of several days’ duration. Approximately 1 year prior she had been admitted to the hospital with similar lesions, with eventual partial necrosis of the left earlobe. The patient reported she had last used crack cocaine 3 days prior to the development of the lesions. A urine drug screen was positive for lorazepam, alprazolam, buprenorphine, methadone, tetrahydrocannabinol, and cocaine. She also reported abdominal pain and gastric reflux of recent onset but denied any history of gastrointestinal tract disease. During the previous admission, the patient demonstrated antinuclear antibodies at a titer of greater than 1:160 (normal, <1:40) in a smooth pattern as well as positive perinuclear antineutrophil cytoplasmic antibodies (p-ANCA) and cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA) and positive cryoglobulins. Physical examination yielded purpuric and hemorrhagic patches and plaques on the nose, bilateral ears (Figure 1A), face (Figure 1B), arms, and legs. Older lesions exhibited evidence of evolving erosion and ulceration. A biopsy of a lesion on the right arm was obtained, demonstrating extensive epidermal necrosis, hemorrhage, fibrin thrombi within dermal blood vessels, fibrinoid mural necrosis, perivascular neutrophils, and leukocytoclasis (Figure 2). These findings were consistent with LIV caused by exposure to LCC. A complete blood cell count was unremarkable. She was started on pain management and was given prednisone to treat the cutaneous eruption. Because of continued reports of epigastric pain and discomfort on swallowing, an upper gastrointestinal endoscopy was performed. Numerous esophageal erosions and gastric submucosal hemorrhages similar to those on the skin were noted (Figure 3). Pathology taken at the time of the endoscopy demonstrated mucosal erosions, but an evaluation for vascular insult was not possible, as submucosal tissue was not obtained. As the skin lesions began to heal, the gastric symptoms gradually subsided, and the patient was released from the hospital after 7 days.

Comment

Levamisole-Contaminated Cocaine
Cocaine is a crystalline alkaloid obtained from the leaves of the coca plant.⁷ Fifty percent of globally produced cocaine is consumed in the United States.¹⁰ There are 2 to 5 million cocaine users in the United States; in 2009, a reported 1.6 million US adults admitted to having used cocaine in the previous month.^4,11,12 Cocaine has been known to be cut with similar-appearing substances including lactose and mannitol, though caffeine, acetaminophen, methylphenidate, and other ingredients have been utilized.⁷

Levamisole is a synthetic imidazothiazole derivative initially developed for use as an immunomodulatory agent in patients with rheumatoid arthritis.⁴ It was later paired with 5-fluorouracil for administration in patients with carcinomas of the colon and breasts.^4,13 In 2000, the drug was withdrawn from the US market for use in humans after an association between levamisole and agranulocytosis was noted in 2.5% to 13% of patients taking the drug for rheumatoid arthritis or as an adjuvant therapy for breast carcinoma.^9,12 It still is available for veterinary use as an anthelmintic and is administered to humans in other countries. Levamisole acts as an immunomodulator by enhancing macrophage chemotaxis and upregulating T-cell functions as well as stimulating neutrophil chemotaxis and dendritic cell maturation.⁴ It also is known to generate autoantibodies including lupus anticoagulant, p-ANCA, c-ANCA, and antinuclear antibodies.^7,14 Levamisole is known to exhibit cutaneous reactions. In 1999, Rongioletti et al¹⁴ reported 5 children with purpura of the ears who had been given levamisole for pediatric nephrotic syndrome. Involvement of other body areas was noted. Three patients developed lupus anticoagulant antibodies, 3 exhibited p-ANCA antibodies, and 1 was positive for c-ANCA antibodies. The investigators noted an exceptionally long latency period of 12 to 44 months after starting the drug. Histologically a vasculopathic/vasculitic process was noted.¹⁴ Direct immunofluorescence studies of affected skin in LIV have demonstrated IgM, IgA, IgG, C3, and fibrin staining of blood vessels.^4,15 Anti–human elastase antibodies are considered both sensitive and specific for LIV and serve to differentiate it from cocaine-induced pseudovasculitis.^4,7

In April 2008, the New Mexico Department of Health began evaluating several unexplained cases of agranulocytosis and noted that 11 of 21 cases were associated with cocaine use.⁹ Later that year, public health workers in Alberta and British Columbia, Canada, reported finding traces of levamisole in clinical specimens and drug paraphernalia of cocaine users with agranulocytosis. Officials from the New Mexico Department of Health learned of these findings and investigated the cases, finding 7 of 9 patients with idiopathic agranulocytosis had recent exposure to cocaine. None of the 21 total patients experienced any skin findings. Nausea and vomiting were common symptoms, but abdominal pain was described in only 2 patients from an additional investigation in Washington. Both of these patients used crack cocaine, and one had a positive urine test for levamisole.⁹

The presence of levamisole initially was detected by the US Drug Enforcement Administration in 2003. By July 2009, 69% of cocaine and 3% of heroin seized by this agency was noted to contain levamisole.¹⁶ From 2003 to 2009, the concentration of levamisole contamination rose to 10%.⁴ A 2011 study found levamisole in 194 of 249 cocaine-positive urine samples.¹⁶

It is unclear why cocaine producers add levamisoleto their product. Possibilities include increasing the drug’s bulk or enhancing its stimulatory effects.¹² Chang et al¹⁷ posited that levamisole increases the stimulatory and euphoric effects of cocaine by increasing dopamine levels in the brain. Additionally, levamisole is metabolized to aminorex, an amphetaminelike hallucinogen that suppresses appetite, in patients with LCC.¹³ Vagi et al¹² interviewed 10 patients who had been hospitalized for agranulocytosis secondary to use of LCC. None were aware of the presence of this additive, suggesting it was not used as a marketing tool.

Cutaneous Vasculopathy
Levamisole-induced vasculopathy (also called levamisole-induced cutaneous vasculopathy¹¹) initially was reported by 2 separate groups in 2010.^1,2 Patients typically present with tender purpuric to hemorrhagic papules, plaques, and bullae with an affinity to affect the ears, nose, and face, though other areas of the body can be affected. A pattern of retiform purpura may precede these findings in some patients. Women are disproportionately affected.¹¹ Crack cocaine use is overrepresented in LIV compared to insufflation or snorting of the drug. Affected patients may exhibit systemic symptoms including myalgia, arthralgia, and frank arthritis.¹⁰ Additionally, 15% to 80% of patients exhibit positive antinuclear antibodies, anticardiolipin antibodies, lupus anticoagulant antibodies, p-ANCA antibodies, and c-ANCA antibodies. Magro and Wang⁸ hypothesized that levamisole acting in conjunction with cocaine rather than the effects of levamisole alone is responsible for some of these findings.

Histologically, the features of a vasculopathic process are noted in some patients with the presence of frank vasculitis.¹ The vasculopathic component demonstrates vessel dilatation with thrombosis, eosinophilic deposits, and erythrocyte extravasation. Patients with frank vasculitis exhibit fibrinoid vessel wall necrosis and fibrin deposition, extravasated erythrocytes, endothelial cell atypia, and leukocytoclasia.³ Jacob et al³ noted interstitial and perivascular neovascularization in affected tissue, believed to represent one stage in the evolution of medium vessel vasculitis. Intercellular adhesion molecule 1 has been reported in affected vessel walls with endothelial caspase 3 expression and C5b-9 deposition.⁸ Magro and Wang⁸ believe the retiform purpura seen in the early stages of some of these patients with LIV represents a thrombotic dynamic with C5b-9 deposition and enhanced apoptosis. Overt vasculitis follows later, subsequent to the effect of ANCA antibodies and upregulated intercellular adhesion molecule 1 expression on vessel walls.

The clinical course of LIV typically is 2 to 3 weeks for lesion resolution; however, normalization of serologies may require 2 to 14 months. Observation and pain control with or without administration of systemic steroids is sufficient for most patients, but skin grafting, wound debridement, cyclosporine, mycophenolate mofetil, and plasmapheresis also have been employed.^4,5 Morbidity may be substantive. One report noted LCC to be responsible for 3 cases of pulmonary hemorrhage and acute progression to chronic renal failure in another 2 patients.¹⁵ Ching and Smith¹⁸ described a patient with 52% total body surface area involvement who required skin grafting, nasal amputation, patellectomy, central upper lip excision, and amputation of the leg above the knee.

Gastrointestinal Presentation
Patients with LIV have been reported to exhibit abdominal pain, but our patient exhibited a rare presentation of visualized gastrointestinal purpura. Although support for a vasculitic/vasculopathic process requires a tissue diagnosis, the endoscopic appearance of gastric vasculitis is similar to that of cutaneous vasculitis.¹⁹ Clinicians caring for patients exposed to LCC should bear in mind that the vascular insults associated with LIV are not restricted solely to the skin.

In 2010, two separate reports of cutaneous vasculitic/vasculopathic eruptions in patients with recent exposure to levamisole-contaminated cocaine (LCC) were published in the literature.^1,2 Since then, additional reports have been published.^3-6 Retiform purpura associated with cocaine use appears to be a similar condition, perhaps lying at one end of the spectrum of LCC-induced cutaneous vascular disease.^7,8 Although some patients have been described as having nausea and vomiting,^8,9 including one with a sudden drop in hemoglobin to 5.8 g/dL (reference range, 14.0–17.5 g/dL),¹⁰ there are no known reported cases of LCC and levamisole-induced vasculopathy in organ systems other than the skin. Herein, we report the case of a patient with levamisole-induced vasculopathy (LIV) demonstrating endoscopic evidence of gastric hemorrhage with features similar to those involving the skin.

Case Report

A 35-year-old woman with a history of hepatitis C, intravenous drug abuse, and bipolar disorder presented to the emergency department with painful necrotic lesions on the head, neck, arms, and legs of several days’ duration. Approximately 1 year prior she had been admitted to the hospital with similar lesions, with eventual partial necrosis of the left earlobe. The patient reported she had last used crack cocaine 3 days prior to the development of the lesions. A urine drug screen was positive for lorazepam, alprazolam, buprenorphine, methadone, tetrahydrocannabinol, and cocaine. She also reported abdominal pain and gastric reflux of recent onset but denied any history of gastrointestinal tract disease. During the previous admission, the patient demonstrated antinuclear antibodies at a titer of greater than 1:160 (normal, <1:40) in a smooth pattern as well as positive perinuclear antineutrophil cytoplasmic antibodies (p-ANCA) and cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA) and positive cryoglobulins. Physical examination yielded purpuric and hemorrhagic patches and plaques on the nose, bilateral ears (Figure 1A), face (Figure 1B), arms, and legs. Older lesions exhibited evidence of evolving erosion and ulceration. A biopsy of a lesion on the right arm was obtained, demonstrating extensive epidermal necrosis, hemorrhage, fibrin thrombi within dermal blood vessels, fibrinoid mural necrosis, perivascular neutrophils, and leukocytoclasis (Figure 2). These findings were consistent with LIV caused by exposure to LCC. A complete blood cell count was unremarkable. She was started on pain management and was given prednisone to treat the cutaneous eruption. Because of continued reports of epigastric pain and discomfort on swallowing, an upper gastrointestinal endoscopy was performed. Numerous esophageal erosions and gastric submucosal hemorrhages similar to those on the skin were noted (Figure 3). Pathology taken at the time of the endoscopy demonstrated mucosal erosions, but an evaluation for vascular insult was not possible, as submucosal tissue was not obtained. As the skin lesions began to heal, the gastric symptoms gradually subsided, and the patient was released from the hospital after 7 days.

Comment

Levamisole-Contaminated Cocaine
Cocaine is a crystalline alkaloid obtained from the leaves of the coca plant.⁷ Fifty percent of globally produced cocaine is consumed in the United States.¹⁰ There are 2 to 5 million cocaine users in the United States; in 2009, a reported 1.6 million US adults admitted to having used cocaine in the previous month.^4,11,12 Cocaine has been known to be cut with similar-appearing substances including lactose and mannitol, though caffeine, acetaminophen, methylphenidate, and other ingredients have been utilized.⁷

Levamisole is a synthetic imidazothiazole derivative initially developed for use as an immunomodulatory agent in patients with rheumatoid arthritis.⁴ It was later paired with 5-fluorouracil for administration in patients with carcinomas of the colon and breasts.^4,13 In 2000, the drug was withdrawn from the US market for use in humans after an association between levamisole and agranulocytosis was noted in 2.5% to 13% of patients taking the drug for rheumatoid arthritis or as an adjuvant therapy for breast carcinoma.^9,12 It still is available for veterinary use as an anthelmintic and is administered to humans in other countries. Levamisole acts as an immunomodulator by enhancing macrophage chemotaxis and upregulating T-cell functions as well as stimulating neutrophil chemotaxis and dendritic cell maturation.⁴ It also is known to generate autoantibodies including lupus anticoagulant, p-ANCA, c-ANCA, and antinuclear antibodies.^7,14 Levamisole is known to exhibit cutaneous reactions. In 1999, Rongioletti et al¹⁴ reported 5 children with purpura of the ears who had been given levamisole for pediatric nephrotic syndrome. Involvement of other body areas was noted. Three patients developed lupus anticoagulant antibodies, 3 exhibited p-ANCA antibodies, and 1 was positive for c-ANCA antibodies. The investigators noted an exceptionally long latency period of 12 to 44 months after starting the drug. Histologically a vasculopathic/vasculitic process was noted.¹⁴ Direct immunofluorescence studies of affected skin in LIV have demonstrated IgM, IgA, IgG, C3, and fibrin staining of blood vessels.^4,15 Anti–human elastase antibodies are considered both sensitive and specific for LIV and serve to differentiate it from cocaine-induced pseudovasculitis.^4,7

In April 2008, the New Mexico Department of Health began evaluating several unexplained cases of agranulocytosis and noted that 11 of 21 cases were associated with cocaine use.⁹ Later that year, public health workers in Alberta and British Columbia, Canada, reported finding traces of levamisole in clinical specimens and drug paraphernalia of cocaine users with agranulocytosis. Officials from the New Mexico Department of Health learned of these findings and investigated the cases, finding 7 of 9 patients with idiopathic agranulocytosis had recent exposure to cocaine. None of the 21 total patients experienced any skin findings. Nausea and vomiting were common symptoms, but abdominal pain was described in only 2 patients from an additional investigation in Washington. Both of these patients used crack cocaine, and one had a positive urine test for levamisole.⁹

The presence of levamisole initially was detected by the US Drug Enforcement Administration in 2003. By July 2009, 69% of cocaine and 3% of heroin seized by this agency was noted to contain levamisole.¹⁶ From 2003 to 2009, the concentration of levamisole contamination rose to 10%.⁴ A 2011 study found levamisole in 194 of 249 cocaine-positive urine samples.¹⁶

It is unclear why cocaine producers add levamisoleto their product. Possibilities include increasing the drug’s bulk or enhancing its stimulatory effects.¹² Chang et al¹⁷ posited that levamisole increases the stimulatory and euphoric effects of cocaine by increasing dopamine levels in the brain. Additionally, levamisole is metabolized to aminorex, an amphetaminelike hallucinogen that suppresses appetite, in patients with LCC.¹³ Vagi et al¹² interviewed 10 patients who had been hospitalized for agranulocytosis secondary to use of LCC. None were aware of the presence of this additive, suggesting it was not used as a marketing tool.

Cutaneous Vasculopathy
Levamisole-induced vasculopathy (also called levamisole-induced cutaneous vasculopathy¹¹) initially was reported by 2 separate groups in 2010.^1,2 Patients typically present with tender purpuric to hemorrhagic papules, plaques, and bullae with an affinity to affect the ears, nose, and face, though other areas of the body can be affected. A pattern of retiform purpura may precede these findings in some patients. Women are disproportionately affected.¹¹ Crack cocaine use is overrepresented in LIV compared to insufflation or snorting of the drug. Affected patients may exhibit systemic symptoms including myalgia, arthralgia, and frank arthritis.¹⁰ Additionally, 15% to 80% of patients exhibit positive antinuclear antibodies, anticardiolipin antibodies, lupus anticoagulant antibodies, p-ANCA antibodies, and c-ANCA antibodies. Magro and Wang⁸ hypothesized that levamisole acting in conjunction with cocaine rather than the effects of levamisole alone is responsible for some of these findings.

Histologically, the features of a vasculopathic process are noted in some patients with the presence of frank vasculitis.¹ The vasculopathic component demonstrates vessel dilatation with thrombosis, eosinophilic deposits, and erythrocyte extravasation. Patients with frank vasculitis exhibit fibrinoid vessel wall necrosis and fibrin deposition, extravasated erythrocytes, endothelial cell atypia, and leukocytoclasia.³ Jacob et al³ noted interstitial and perivascular neovascularization in affected tissue, believed to represent one stage in the evolution of medium vessel vasculitis. Intercellular adhesion molecule 1 has been reported in affected vessel walls with endothelial caspase 3 expression and C5b-9 deposition.⁸ Magro and Wang⁸ believe the retiform purpura seen in the early stages of some of these patients with LIV represents a thrombotic dynamic with C5b-9 deposition and enhanced apoptosis. Overt vasculitis follows later, subsequent to the effect of ANCA antibodies and upregulated intercellular adhesion molecule 1 expression on vessel walls.

The clinical course of LIV typically is 2 to 3 weeks for lesion resolution; however, normalization of serologies may require 2 to 14 months. Observation and pain control with or without administration of systemic steroids is sufficient for most patients, but skin grafting, wound debridement, cyclosporine, mycophenolate mofetil, and plasmapheresis also have been employed.^4,5 Morbidity may be substantive. One report noted LCC to be responsible for 3 cases of pulmonary hemorrhage and acute progression to chronic renal failure in another 2 patients.¹⁵ Ching and Smith¹⁸ described a patient with 52% total body surface area involvement who required skin grafting, nasal amputation, patellectomy, central upper lip excision, and amputation of the leg above the knee.

Gastrointestinal Presentation
Patients with LIV have been reported to exhibit abdominal pain, but our patient exhibited a rare presentation of visualized gastrointestinal purpura. Although support for a vasculitic/vasculopathic process requires a tissue diagnosis, the endoscopic appearance of gastric vasculitis is similar to that of cutaneous vasculitis.¹⁹ Clinicians caring for patients exposed to LCC should bear in mind that the vascular insults associated with LIV are not restricted solely to the skin.

In 2010, two separate reports of cutaneous vasculitic/vasculopathic eruptions in patients with recent exposure to levamisole-contaminated cocaine (LCC) were published in the literature.^1,2 Since then, additional reports have been published.^3-6 Retiform purpura associated with cocaine use appears to be a similar condition, perhaps lying at one end of the spectrum of LCC-induced cutaneous vascular disease.^7,8 Although some patients have been described as having nausea and vomiting,^8,9 including one with a sudden drop in hemoglobin to 5.8 g/dL (reference range, 14.0–17.5 g/dL),¹⁰ there are no known reported cases of LCC and levamisole-induced vasculopathy in organ systems other than the skin. Herein, we report the case of a patient with levamisole-induced vasculopathy (LIV) demonstrating endoscopic evidence of gastric hemorrhage with features similar to those involving the skin.

Case Report

A 35-year-old woman with a history of hepatitis C, intravenous drug abuse, and bipolar disorder presented to the emergency department with painful necrotic lesions on the head, neck, arms, and legs of several days’ duration. Approximately 1 year prior she had been admitted to the hospital with similar lesions, with eventual partial necrosis of the left earlobe. The patient reported she had last used crack cocaine 3 days prior to the development of the lesions. A urine drug screen was positive for lorazepam, alprazolam, buprenorphine, methadone, tetrahydrocannabinol, and cocaine. She also reported abdominal pain and gastric reflux of recent onset but denied any history of gastrointestinal tract disease. During the previous admission, the patient demonstrated antinuclear antibodies at a titer of greater than 1:160 (normal, <1:40) in a smooth pattern as well as positive perinuclear antineutrophil cytoplasmic antibodies (p-ANCA) and cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA) and positive cryoglobulins. Physical examination yielded purpuric and hemorrhagic patches and plaques on the nose, bilateral ears (Figure 1A), face (Figure 1B), arms, and legs. Older lesions exhibited evidence of evolving erosion and ulceration. A biopsy of a lesion on the right arm was obtained, demonstrating extensive epidermal necrosis, hemorrhage, fibrin thrombi within dermal blood vessels, fibrinoid mural necrosis, perivascular neutrophils, and leukocytoclasis (Figure 2). These findings were consistent with LIV caused by exposure to LCC. A complete blood cell count was unremarkable. She was started on pain management and was given prednisone to treat the cutaneous eruption. Because of continued reports of epigastric pain and discomfort on swallowing, an upper gastrointestinal endoscopy was performed. Numerous esophageal erosions and gastric submucosal hemorrhages similar to those on the skin were noted (Figure 3). Pathology taken at the time of the endoscopy demonstrated mucosal erosions, but an evaluation for vascular insult was not possible, as submucosal tissue was not obtained. As the skin lesions began to heal, the gastric symptoms gradually subsided, and the patient was released from the hospital after 7 days.

Comment

Levamisole-Contaminated Cocaine
Cocaine is a crystalline alkaloid obtained from the leaves of the coca plant.⁷ Fifty percent of globally produced cocaine is consumed in the United States.¹⁰ There are 2 to 5 million cocaine users in the United States; in 2009, a reported 1.6 million US adults admitted to having used cocaine in the previous month.^4,11,12 Cocaine has been known to be cut with similar-appearing substances including lactose and mannitol, though caffeine, acetaminophen, methylphenidate, and other ingredients have been utilized.⁷

Levamisole is a synthetic imidazothiazole derivative initially developed for use as an immunomodulatory agent in patients with rheumatoid arthritis.⁴ It was later paired with 5-fluorouracil for administration in patients with carcinomas of the colon and breasts.^4,13 In 2000, the drug was withdrawn from the US market for use in humans after an association between levamisole and agranulocytosis was noted in 2.5% to 13% of patients taking the drug for rheumatoid arthritis or as an adjuvant therapy for breast carcinoma.^9,12 It still is available for veterinary use as an anthelmintic and is administered to humans in other countries. Levamisole acts as an immunomodulator by enhancing macrophage chemotaxis and upregulating T-cell functions as well as stimulating neutrophil chemotaxis and dendritic cell maturation.⁴ It also is known to generate autoantibodies including lupus anticoagulant, p-ANCA, c-ANCA, and antinuclear antibodies.^7,14 Levamisole is known to exhibit cutaneous reactions. In 1999, Rongioletti et al¹⁴ reported 5 children with purpura of the ears who had been given levamisole for pediatric nephrotic syndrome. Involvement of other body areas was noted. Three patients developed lupus anticoagulant antibodies, 3 exhibited p-ANCA antibodies, and 1 was positive for c-ANCA antibodies. The investigators noted an exceptionally long latency period of 12 to 44 months after starting the drug. Histologically a vasculopathic/vasculitic process was noted.¹⁴ Direct immunofluorescence studies of affected skin in LIV have demonstrated IgM, IgA, IgG, C3, and fibrin staining of blood vessels.^4,15 Anti–human elastase antibodies are considered both sensitive and specific for LIV and serve to differentiate it from cocaine-induced pseudovasculitis.^4,7

In April 2008, the New Mexico Department of Health began evaluating several unexplained cases of agranulocytosis and noted that 11 of 21 cases were associated with cocaine use.⁹ Later that year, public health workers in Alberta and British Columbia, Canada, reported finding traces of levamisole in clinical specimens and drug paraphernalia of cocaine users with agranulocytosis. Officials from the New Mexico Department of Health learned of these findings and investigated the cases, finding 7 of 9 patients with idiopathic agranulocytosis had recent exposure to cocaine. None of the 21 total patients experienced any skin findings. Nausea and vomiting were common symptoms, but abdominal pain was described in only 2 patients from an additional investigation in Washington. Both of these patients used crack cocaine, and one had a positive urine test for levamisole.⁹

The presence of levamisole initially was detected by the US Drug Enforcement Administration in 2003. By July 2009, 69% of cocaine and 3% of heroin seized by this agency was noted to contain levamisole.¹⁶ From 2003 to 2009, the concentration of levamisole contamination rose to 10%.⁴ A 2011 study found levamisole in 194 of 249 cocaine-positive urine samples.¹⁶

It is unclear why cocaine producers add levamisoleto their product. Possibilities include increasing the drug’s bulk or enhancing its stimulatory effects.¹² Chang et al¹⁷ posited that levamisole increases the stimulatory and euphoric effects of cocaine by increasing dopamine levels in the brain. Additionally, levamisole is metabolized to aminorex, an amphetaminelike hallucinogen that suppresses appetite, in patients with LCC.¹³ Vagi et al¹² interviewed 10 patients who had been hospitalized for agranulocytosis secondary to use of LCC. None were aware of the presence of this additive, suggesting it was not used as a marketing tool.

Cutaneous Vasculopathy
Levamisole-induced vasculopathy (also called levamisole-induced cutaneous vasculopathy¹¹) initially was reported by 2 separate groups in 2010.^1,2 Patients typically present with tender purpuric to hemorrhagic papules, plaques, and bullae with an affinity to affect the ears, nose, and face, though other areas of the body can be affected. A pattern of retiform purpura may precede these findings in some patients. Women are disproportionately affected.¹¹ Crack cocaine use is overrepresented in LIV compared to insufflation or snorting of the drug. Affected patients may exhibit systemic symptoms including myalgia, arthralgia, and frank arthritis.¹⁰ Additionally, 15% to 80% of patients exhibit positive antinuclear antibodies, anticardiolipin antibodies, lupus anticoagulant antibodies, p-ANCA antibodies, and c-ANCA antibodies. Magro and Wang⁸ hypothesized that levamisole acting in conjunction with cocaine rather than the effects of levamisole alone is responsible for some of these findings.

Histologically, the features of a vasculopathic process are noted in some patients with the presence of frank vasculitis.¹ The vasculopathic component demonstrates vessel dilatation with thrombosis, eosinophilic deposits, and erythrocyte extravasation. Patients with frank vasculitis exhibit fibrinoid vessel wall necrosis and fibrin deposition, extravasated erythrocytes, endothelial cell atypia, and leukocytoclasia.³ Jacob et al³ noted interstitial and perivascular neovascularization in affected tissue, believed to represent one stage in the evolution of medium vessel vasculitis. Intercellular adhesion molecule 1 has been reported in affected vessel walls with endothelial caspase 3 expression and C5b-9 deposition.⁸ Magro and Wang⁸ believe the retiform purpura seen in the early stages of some of these patients with LIV represents a thrombotic dynamic with C5b-9 deposition and enhanced apoptosis. Overt vasculitis follows later, subsequent to the effect of ANCA antibodies and upregulated intercellular adhesion molecule 1 expression on vessel walls.

The clinical course of LIV typically is 2 to 3 weeks for lesion resolution; however, normalization of serologies may require 2 to 14 months. Observation and pain control with or without administration of systemic steroids is sufficient for most patients, but skin grafting, wound debridement, cyclosporine, mycophenolate mofetil, and plasmapheresis also have been employed.^4,5 Morbidity may be substantive. One report noted LCC to be responsible for 3 cases of pulmonary hemorrhage and acute progression to chronic renal failure in another 2 patients.¹⁵ Ching and Smith¹⁸ described a patient with 52% total body surface area involvement who required skin grafting, nasal amputation, patellectomy, central upper lip excision, and amputation of the leg above the knee.

Gastrointestinal Presentation
Patients with LIV have been reported to exhibit abdominal pain, but our patient exhibited a rare presentation of visualized gastrointestinal purpura. Although support for a vasculitic/vasculopathic process requires a tissue diagnosis, the endoscopic appearance of gastric vasculitis is similar to that of cutaneous vasculitis.¹⁹ Clinicians caring for patients exposed to LCC should bear in mind that the vascular insults associated with LIV are not restricted solely to the skin.

The Diagnosis: Bacterial Infection

The tetrad arrangement of organisms seen in this case was classic for Micrococcus and Sarcina species. Both are gram-positive cocci that occur in tetrads, but Micrococcus is aerobic and catalase positive, whereas Sarcina species are anaerobic, catalase negative, acidophilic, and form spores in alkaline pH.¹ Although difficult to definitively differentiate on light microscopy, micrococci are smaller in size, ranging from 0.5 to 2.0 μm, and occur in tight clusters, as seen in this case (quiz images), in contrast to Sarcina species, which are relatively larger (1.8-3.0 μm).² Sarcinae typically are found in soil and air, are considered pathogenic, and are associated with gastric symptoms (Sarcina ventriculi).¹Sarcina species also are reported to colonize the skin of patients with diabetes mellitus, but no pathogenic activity is known in the skin.³Micrococcus species, with the majority being Micrococcus luteus, are part of the normal flora of the human skin as well as the oral and nasal cavities. Occasional reports of pneumonia, endocarditis, meningitis, arthritis, endophthalmitis, and sepsis have been reported in immunocompromised individuals.⁴ In the skin, Micrococcus is a commensal organism; however, Micrococcus sedentarius has been associated with pitted keratolysis, and reports of Micrococcus folliculitis in human immunodeficiency virus patients also are described in the literature.^5,6 Micrococci are considered opportunistic bacteria and may worsen and prolong a localized cutaneous infection caused by other organisms under favorable conditions.⁷Micrococcus luteus is one of the most common bacteria cultured from skin and soft tissue infections caused by fungal organisms.⁸ Depending on the immune status of an individual, use of broad-spectrum antibiotic and/or elimination of favorable milieu (ie, primary pathogen, breaks in skin) usually treats the infection.

Because of the rarity of infections caused and being part of the normal flora, the clinical implications of subtyping and sensitivity studies via culture or molecular studies may not be important; however, incidental presence of these organisms with unfamiliar morphology may cause confusion for the dermatopathologist. An extremely small size (0.5-2.0 μm) compared to red blood cells (7-8 μm) and white blood cells (10-12 μm) in a tight tetrad arrangement should raise the suspicion for Micrococcus.1 The refractive nature of these organisms from a thick extracellular layer can mimic fungus or plant matter; a negative Grocott-Gomori methenamine-silver stain in this case helped in not only differentiating but also ruling out secondary fungal infection. Finally, a Gram stain with violet staining of these organisms reaffirmed the diagnosis of gram-positive bacterial organisms, most consistent with Micrococcus species (Figure 1). Culture studies were not performed because of contamination of the tissue specimen and resolution of the patient's symptoms.

The presence of foreign material in the skin may be traumatic, occupational, cosmetic, iatrogenic, or self-inflicted, including a wide variety of substances that appear in different morphological forms on hematoxylin and eosin (H&E)-stained sections, depending on their structure and physiochemical properties.⁹ Although not all foreign bodies may polarize, examining the sample under polarized light is considered an important step to narrow down the differential diagnosis. The tissue reaction is primarily dependent on the nature of the substance and duration, consisting of histiocytes, macrophages, plasma cells, lymphocytes, and fibrosis.⁹ Activated histiocytes, multinucleated giant cells, and granulomas are classic findings that generally are seen surrounding and engulfing the foreign material (Figure 2). In addition to foreign material, substances such as calcium salts, urate crystals, extruded keratin, ruptured cysts, and hair follicles may act as foreign materials and can incite a tissue response.⁹ Absence of histiocytic response, granuloma formation, and fibrosis in a lesion of 1 month's duration made the tetrad bodies unlikely to be foreign material.

Demodex mites are superficial inhabitants of human skin that are acquired shortly after birth, live in or near pilosebaceous units, and obtain nourishment from skin cells and sebum.^10,11 The mites can be recovered on 10% of skin biopsies, most commonly on the face due to high sebum production.¹⁰ Adult mites range from 0.1 to 0.4 mm in length and are round to oval in shape. Females lay eggs inside the hair follicle or sebaceous glands.¹¹ They usually are asymptomatic, but their infestation may become pathogenic, especially in immunocompromised individuals.¹⁰ The clinical picture may resemble bacterial folliculitis, rosacea, and perioral dermatitis, while histology typically is characterized by spongiosis, lymphohistiocytic inflammation around infested follicles, and mite(s) in follicular infundibula (Figure 3). Sometimes the protrusion of mites and keratin from the follicles is seen as follicular spines on histology and referred to as pityriasis folliculorum.

Deposits of urate crystals in skin occur from the elevated serum uric acid levels in gout. The cutaneous deposits are mainly in the dermis and subcutaneous tissue and are extremely painful.¹² Urate crystals get dissolved during formalin fixation and leave needlelike clefts in a homogenous, lightly basophilic material on H&E slide (Figure 4). For the same reason, polarized microscopy also is not helpful despite the birefringent nature of urate crystals.¹²

Fungal yeast forms appear round to oval under light microscopy, ranging from 2 to 100 μm in size.¹³ The common superficial forms involving the epidermis or hair follicles similar to the current case of bacterial infection include Malassezia and dermatophyte infections. Malassezia is part of the normal flora of sebum-rich areas of skin and is associated with superficial infections such as folliculitis, atopic dermatitis, psoriasis, seborrheic dermatitis, and dandruff.¹⁴Malassezia appear as clusters of yeast cells that are pleomorphic and round to oval in shape, ranging from 2 to 6 μm in size. It forms hyphae in its pathogenic form and gives rise to the classic spaghetti and meatball-like appearance that can be highlighted by periodic acid-Schiff (Figure 5) and Grocott-Gomori methenamine-silver special stains. Dermatophytes include 3 genera--Trichophyton, Microsporum, and Epidermophyton--with at least 40 species that causes skin infections in humans.¹⁴ Fungal spores and hyphae forms are restricted to the stratum corneum. The hyphae forms may not be apparent on H&E stain, and periodic acid-Schiff staining is helpful in visualizing the fungal elements. The presence of neutrophils in the corneal layer, basket weave hyperkeratosis, and presence of fungal hyphae within the corneal layer fissures (sandwich sign) are clues to the dermatophyte infection.¹⁵ Other smaller fungi such as Histoplasma capsulatum (2-4 μm), Candida (3-5 μm), and Pneumocystis (2-5 μm) species can be found in skin in disseminated infections, usually affecting immunocompromised individuals.¹³Histoplasma is a basophilic yeast that exhibits narrow-based budding and appears clustered within or outside of macrophages. Candida species generally are dimorphic, and yeasts are found intermingled with filamentous forms. Pneumocystis infection in skin is extremely rare, and the fungi appear as spherical or crescent-shaped bodies in a foamy amorphous material.¹⁶

The Diagnosis: Bacterial Infection

The tetrad arrangement of organisms seen in this case was classic for Micrococcus and Sarcina species. Both are gram-positive cocci that occur in tetrads, but Micrococcus is aerobic and catalase positive, whereas Sarcina species are anaerobic, catalase negative, acidophilic, and form spores in alkaline pH.¹ Although difficult to definitively differentiate on light microscopy, micrococci are smaller in size, ranging from 0.5 to 2.0 μm, and occur in tight clusters, as seen in this case (quiz images), in contrast to Sarcina species, which are relatively larger (1.8-3.0 μm).² Sarcinae typically are found in soil and air, are considered pathogenic, and are associated with gastric symptoms (Sarcina ventriculi).¹Sarcina species also are reported to colonize the skin of patients with diabetes mellitus, but no pathogenic activity is known in the skin.³Micrococcus species, with the majority being Micrococcus luteus, are part of the normal flora of the human skin as well as the oral and nasal cavities. Occasional reports of pneumonia, endocarditis, meningitis, arthritis, endophthalmitis, and sepsis have been reported in immunocompromised individuals.⁴ In the skin, Micrococcus is a commensal organism; however, Micrococcus sedentarius has been associated with pitted keratolysis, and reports of Micrococcus folliculitis in human immunodeficiency virus patients also are described in the literature.^5,6 Micrococci are considered opportunistic bacteria and may worsen and prolong a localized cutaneous infection caused by other organisms under favorable conditions.⁷Micrococcus luteus is one of the most common bacteria cultured from skin and soft tissue infections caused by fungal organisms.⁸ Depending on the immune status of an individual, use of broad-spectrum antibiotic and/or elimination of favorable milieu (ie, primary pathogen, breaks in skin) usually treats the infection.

Because of the rarity of infections caused and being part of the normal flora, the clinical implications of subtyping and sensitivity studies via culture or molecular studies may not be important; however, incidental presence of these organisms with unfamiliar morphology may cause confusion for the dermatopathologist. An extremely small size (0.5-2.0 μm) compared to red blood cells (7-8 μm) and white blood cells (10-12 μm) in a tight tetrad arrangement should raise the suspicion for Micrococcus.1 The refractive nature of these organisms from a thick extracellular layer can mimic fungus or plant matter; a negative Grocott-Gomori methenamine-silver stain in this case helped in not only differentiating but also ruling out secondary fungal infection. Finally, a Gram stain with violet staining of these organisms reaffirmed the diagnosis of gram-positive bacterial organisms, most consistent with Micrococcus species (Figure 1). Culture studies were not performed because of contamination of the tissue specimen and resolution of the patient's symptoms.

The presence of foreign material in the skin may be traumatic, occupational, cosmetic, iatrogenic, or self-inflicted, including a wide variety of substances that appear in different morphological forms on hematoxylin and eosin (H&E)-stained sections, depending on their structure and physiochemical properties.⁹ Although not all foreign bodies may polarize, examining the sample under polarized light is considered an important step to narrow down the differential diagnosis. The tissue reaction is primarily dependent on the nature of the substance and duration, consisting of histiocytes, macrophages, plasma cells, lymphocytes, and fibrosis.⁹ Activated histiocytes, multinucleated giant cells, and granulomas are classic findings that generally are seen surrounding and engulfing the foreign material (Figure 2). In addition to foreign material, substances such as calcium salts, urate crystals, extruded keratin, ruptured cysts, and hair follicles may act as foreign materials and can incite a tissue response.⁹ Absence of histiocytic response, granuloma formation, and fibrosis in a lesion of 1 month's duration made the tetrad bodies unlikely to be foreign material.

Demodex mites are superficial inhabitants of human skin that are acquired shortly after birth, live in or near pilosebaceous units, and obtain nourishment from skin cells and sebum.^10,11 The mites can be recovered on 10% of skin biopsies, most commonly on the face due to high sebum production.¹⁰ Adult mites range from 0.1 to 0.4 mm in length and are round to oval in shape. Females lay eggs inside the hair follicle or sebaceous glands.¹¹ They usually are asymptomatic, but their infestation may become pathogenic, especially in immunocompromised individuals.¹⁰ The clinical picture may resemble bacterial folliculitis, rosacea, and perioral dermatitis, while histology typically is characterized by spongiosis, lymphohistiocytic inflammation around infested follicles, and mite(s) in follicular infundibula (Figure 3). Sometimes the protrusion of mites and keratin from the follicles is seen as follicular spines on histology and referred to as pityriasis folliculorum.

Deposits of urate crystals in skin occur from the elevated serum uric acid levels in gout. The cutaneous deposits are mainly in the dermis and subcutaneous tissue and are extremely painful.¹² Urate crystals get dissolved during formalin fixation and leave needlelike clefts in a homogenous, lightly basophilic material on H&E slide (Figure 4). For the same reason, polarized microscopy also is not helpful despite the birefringent nature of urate crystals.¹²

Fungal yeast forms appear round to oval under light microscopy, ranging from 2 to 100 μm in size.¹³ The common superficial forms involving the epidermis or hair follicles similar to the current case of bacterial infection include Malassezia and dermatophyte infections. Malassezia is part of the normal flora of sebum-rich areas of skin and is associated with superficial infections such as folliculitis, atopic dermatitis, psoriasis, seborrheic dermatitis, and dandruff.¹⁴Malassezia appear as clusters of yeast cells that are pleomorphic and round to oval in shape, ranging from 2 to 6 μm in size. It forms hyphae in its pathogenic form and gives rise to the classic spaghetti and meatball-like appearance that can be highlighted by periodic acid-Schiff (Figure 5) and Grocott-Gomori methenamine-silver special stains. Dermatophytes include 3 genera--Trichophyton, Microsporum, and Epidermophyton--with at least 40 species that causes skin infections in humans.¹⁴ Fungal spores and hyphae forms are restricted to the stratum corneum. The hyphae forms may not be apparent on H&E stain, and periodic acid-Schiff staining is helpful in visualizing the fungal elements. The presence of neutrophils in the corneal layer, basket weave hyperkeratosis, and presence of fungal hyphae within the corneal layer fissures (sandwich sign) are clues to the dermatophyte infection.¹⁵ Other smaller fungi such as Histoplasma capsulatum (2-4 μm), Candida (3-5 μm), and Pneumocystis (2-5 μm) species can be found in skin in disseminated infections, usually affecting immunocompromised individuals.¹³Histoplasma is a basophilic yeast that exhibits narrow-based budding and appears clustered within or outside of macrophages. Candida species generally are dimorphic, and yeasts are found intermingled with filamentous forms. Pneumocystis infection in skin is extremely rare, and the fungi appear as spherical or crescent-shaped bodies in a foamy amorphous material.¹⁶

The Diagnosis: Bacterial Infection

The tetrad arrangement of organisms seen in this case was classic for Micrococcus and Sarcina species. Both are gram-positive cocci that occur in tetrads, but Micrococcus is aerobic and catalase positive, whereas Sarcina species are anaerobic, catalase negative, acidophilic, and form spores in alkaline pH.¹ Although difficult to definitively differentiate on light microscopy, micrococci are smaller in size, ranging from 0.5 to 2.0 μm, and occur in tight clusters, as seen in this case (quiz images), in contrast to Sarcina species, which are relatively larger (1.8-3.0 μm).² Sarcinae typically are found in soil and air, are considered pathogenic, and are associated with gastric symptoms (Sarcina ventriculi).¹Sarcina species also are reported to colonize the skin of patients with diabetes mellitus, but no pathogenic activity is known in the skin.³Micrococcus species, with the majority being Micrococcus luteus, are part of the normal flora of the human skin as well as the oral and nasal cavities. Occasional reports of pneumonia, endocarditis, meningitis, arthritis, endophthalmitis, and sepsis have been reported in immunocompromised individuals.⁴ In the skin, Micrococcus is a commensal organism; however, Micrococcus sedentarius has been associated with pitted keratolysis, and reports of Micrococcus folliculitis in human immunodeficiency virus patients also are described in the literature.^5,6 Micrococci are considered opportunistic bacteria and may worsen and prolong a localized cutaneous infection caused by other organisms under favorable conditions.⁷Micrococcus luteus is one of the most common bacteria cultured from skin and soft tissue infections caused by fungal organisms.⁸ Depending on the immune status of an individual, use of broad-spectrum antibiotic and/or elimination of favorable milieu (ie, primary pathogen, breaks in skin) usually treats the infection.

Because of the rarity of infections caused and being part of the normal flora, the clinical implications of subtyping and sensitivity studies via culture or molecular studies may not be important; however, incidental presence of these organisms with unfamiliar morphology may cause confusion for the dermatopathologist. An extremely small size (0.5-2.0 μm) compared to red blood cells (7-8 μm) and white blood cells (10-12 μm) in a tight tetrad arrangement should raise the suspicion for Micrococcus.1 The refractive nature of these organisms from a thick extracellular layer can mimic fungus or plant matter; a negative Grocott-Gomori methenamine-silver stain in this case helped in not only differentiating but also ruling out secondary fungal infection. Finally, a Gram stain with violet staining of these organisms reaffirmed the diagnosis of gram-positive bacterial organisms, most consistent with Micrococcus species (Figure 1). Culture studies were not performed because of contamination of the tissue specimen and resolution of the patient's symptoms.

The presence of foreign material in the skin may be traumatic, occupational, cosmetic, iatrogenic, or self-inflicted, including a wide variety of substances that appear in different morphological forms on hematoxylin and eosin (H&E)-stained sections, depending on their structure and physiochemical properties.⁹ Although not all foreign bodies may polarize, examining the sample under polarized light is considered an important step to narrow down the differential diagnosis. The tissue reaction is primarily dependent on the nature of the substance and duration, consisting of histiocytes, macrophages, plasma cells, lymphocytes, and fibrosis.⁹ Activated histiocytes, multinucleated giant cells, and granulomas are classic findings that generally are seen surrounding and engulfing the foreign material (Figure 2). In addition to foreign material, substances such as calcium salts, urate crystals, extruded keratin, ruptured cysts, and hair follicles may act as foreign materials and can incite a tissue response.⁹ Absence of histiocytic response, granuloma formation, and fibrosis in a lesion of 1 month's duration made the tetrad bodies unlikely to be foreign material.

Demodex mites are superficial inhabitants of human skin that are acquired shortly after birth, live in or near pilosebaceous units, and obtain nourishment from skin cells and sebum.^10,11 The mites can be recovered on 10% of skin biopsies, most commonly on the face due to high sebum production.¹⁰ Adult mites range from 0.1 to 0.4 mm in length and are round to oval in shape. Females lay eggs inside the hair follicle or sebaceous glands.¹¹ They usually are asymptomatic, but their infestation may become pathogenic, especially in immunocompromised individuals.¹⁰ The clinical picture may resemble bacterial folliculitis, rosacea, and perioral dermatitis, while histology typically is characterized by spongiosis, lymphohistiocytic inflammation around infested follicles, and mite(s) in follicular infundibula (Figure 3). Sometimes the protrusion of mites and keratin from the follicles is seen as follicular spines on histology and referred to as pityriasis folliculorum.

Deposits of urate crystals in skin occur from the elevated serum uric acid levels in gout. The cutaneous deposits are mainly in the dermis and subcutaneous tissue and are extremely painful.¹² Urate crystals get dissolved during formalin fixation and leave needlelike clefts in a homogenous, lightly basophilic material on H&E slide (Figure 4). For the same reason, polarized microscopy also is not helpful despite the birefringent nature of urate crystals.¹²

Fungal yeast forms appear round to oval under light microscopy, ranging from 2 to 100 μm in size.¹³ The common superficial forms involving the epidermis or hair follicles similar to the current case of bacterial infection include Malassezia and dermatophyte infections. Malassezia is part of the normal flora of sebum-rich areas of skin and is associated with superficial infections such as folliculitis, atopic dermatitis, psoriasis, seborrheic dermatitis, and dandruff.¹⁴Malassezia appear as clusters of yeast cells that are pleomorphic and round to oval in shape, ranging from 2 to 6 μm in size. It forms hyphae in its pathogenic form and gives rise to the classic spaghetti and meatball-like appearance that can be highlighted by periodic acid-Schiff (Figure 5) and Grocott-Gomori methenamine-silver special stains. Dermatophytes include 3 genera--Trichophyton, Microsporum, and Epidermophyton--with at least 40 species that causes skin infections in humans.¹⁴ Fungal spores and hyphae forms are restricted to the stratum corneum. The hyphae forms may not be apparent on H&E stain, and periodic acid-Schiff staining is helpful in visualizing the fungal elements. The presence of neutrophils in the corneal layer, basket weave hyperkeratosis, and presence of fungal hyphae within the corneal layer fissures (sandwich sign) are clues to the dermatophyte infection.¹⁵ Other smaller fungi such as Histoplasma capsulatum (2-4 μm), Candida (3-5 μm), and Pneumocystis (2-5 μm) species can be found in skin in disseminated infections, usually affecting immunocompromised individuals.¹³Histoplasma is a basophilic yeast that exhibits narrow-based budding and appears clustered within or outside of macrophages. Candida species generally are dimorphic, and yeasts are found intermingled with filamentous forms. Pneumocystis infection in skin is extremely rare, and the fungi appear as spherical or crescent-shaped bodies in a foamy amorphous material.¹⁶

Dermatologists are uniquely equipped amongst clinicians to make bedside diagnoses because of the focus on histopathology and microscopy inherent in our training. This skill is highly valuable in both an inpatient and outpatient setting because it may lead to a rapid diagnosis or be a useful adjunct in the initial clinical decision-making process. Although expert microscopists may be able to garner relevant information from scraping almost any type of lesion, bedside microscopy primarily is used by dermatologists in the United States for consideration of infectious etiologies of a variety of cutaneous manifestations.^1,2

Basic Principles

Lesions that should be considered for bedside microscopic analysis in outpatient settings are scaly lesions, vesiculobullous lesions, inflammatory papules, and pustules¹; microscopic evaluation also can be useful for myriad trichoscopic considerations.^3,4 In some instances, direct visualization of the pathogen is possible (eg, cutaneous fungal infections, demodicidosis, scabetic infections), and in other circumstances reactive changes of keratinocytes or the presence of specific cell types can aid in diagnosis (eg, ballooning degeneration and multinucleation of keratinocytes in herpetic lesions, an abundance of eosinophils in erythema toxicum neonatorum). Different types of media are used to best prepare tissue based on the suspected etiology of the condition.

One major stumbling block for residents when beginning to perform bedside testing is the lack of dimensional understanding of the structures they are searching for; for example, medical students and residents often may mistake fibers for dermatophytes, which typically are much larger than fungal hyphae. Familiarizing oneself with the basic dimensions of different cell types or pathogens in relation to each other (Table) will help further refine the beginner’s ability to effectively search for and identify pathogenic features. This concept is further schematized in Figure 1 to help visualize scale differences.

Image courtesy of Bogdan Mohora, MS (Austin, Texas).

Examination of the Specimen

Slide preparation depends on the primary lesion in consideration and will be discussed in greater detail in the following sections. Once the slide is prepared, place it on the microscope stage and adjust the condenser and light source for optimal visualization. Scan the specimen in a gridlike fashion on low power (usually ×10) and then inspect suspicious findings on higher power (×40 or higher).

Dermatomycoses

Fungal infections of the skin can present as annular papulosquamous lesions, follicular pustules or papules, bullous lesions, hypopigmented patches, and mucosal exudate or erosions, among other manifestations.⁵ Potassium hydroxide (KOH) is the classic medium used in preparation of lesions being assessed for evidence of fungus because it leads to lysis of keratinocytes for better visualization of fungal hyphae and spores. Other media that contain KOH and additional substrates such as dimethyl sulfoxide or chlorazol black E can be used to better highlight fungal elements.⁶

Dermatophytosis
Dermatophytes lead to superficial infection of the epidermis and epidermal appendages and present in a variety of ways, including site-specific infections manifesting typically as erythematous, annular or arcuate scaling (eg, tinea faciei, tinea corporis, tinea cruris, tinea manus, tinea pedis), alopecia with broken hair shafts, black dots, boggy nodules and/or scaling of the scalp (eg, tinea capitis, favus, kerion), and dystrophic nails (eg, onychomycosis).^5,7 For examination of lesional skin scrapings, one can either use clear cellophane tape against the skin to remove scale, which is especially useful in the case of pediatric patients, and then press the tape against a slide prepared with several drops of a KOH-based medium to directly visualize without a coverslip, or scrape the lesion with a No. 15 blade and place the scales onto the glass slide, with further preparation as described below.⁸ For assessment of alopecia or dystrophic nails, scrape lesional skin with a No. 15 blade to obtain affected hair follicles and proximal subungual debris, respectively.^6,9

Once the cellular debris has been obtained and placed on the slide, a coverslip can be overlaid and KOH applied laterally to be taken up across the slide by capillary action. Allow the slide to sit for at least 5 minutes before analyzing to better visualize fungal elements. Both tinea and onychomycosis will show branching septate hyphae extending across keratinocytes; a common false-positive is identifying overlapping keratinocyte edges, which are a similar size, but they can be distinguished from fungi because they do not cross multiple keratinocytes.^1,8 Tinea capitis may demonstrate similar findings or may reveal hair shafts with spores contained within or surrounding it, corresponding to endothrix or ectothrix infection, respectively.⁵

Pityriasis Versicolor and Malassezia Folliculitis
Pityriasis versicolor presents with hypopigmented to pink, finely scaling ovoid papules, usually on the upper back, shoulders, and neck, and is caused by Malassezia furfur and other Malassezia species.⁵ Malassezia folliculitis also is caused by this fungus and presents with monomorphic follicular papules and pustules. Scrapings from the scaly papules will demonstrate keratinocytes with the classic “spaghetti and meatballs” fungal elements, whereas Malassezia folliculitis demonstrates only spores.^5,7

Candidiasis
One possible outpatient presentation of candidiasis is oral thrush, which can exhibit white mucosal exudate or erythematous patches. A tongue blade can be used to scrape the tongue or cheek wall, with subsequent preparatory steps with application of KOH as described for dermatophytes. Cutaneous candidiasis most often develops in intertriginous regions and will exhibit erosive painful lesions with satellite pustules. In both cases, analysis of the specimen will show shorter fatter hyphal elements than seen in dermatophytosis, with pseudohyphae, blunted ends, and potentially yeast forms.⁵

Vesiculobullous Lesions

The Tzanck smear has been used since the 1940s to differentiate between etiologies of blistering disorders and is now most commonly used for the quick identification of herpetic lesions.¹ The test is performed by scraping the base of a deroofed vesicle, pustule, or bulla, and smearing the cellular materials onto a glass slide. The most commonly utilized media for staining in the outpatient setting at my institution (University of Texas Dell Medical School, Austin) is Giemsa, which is composed of azure II–eosin, glycerin, and methanol. It stains nuclei a reddish blue to pink and the cytoplasm blue.¹⁰ After being applied to the slide, the cells are allowed to air-dry for 5 to 10 minutes, and Giemsa stain is subsequently applied and allowed to incubate for 15 minutes, then rinsed carefully with water and directly examined.

Other stains that can be used to perform the Tzanck smear include commercial preparations that may be more accessible in the inpatient settings such as the Wright-Giemsa, Quik-Dip, and Diff-Quick.^1,10

Examination of a Tzanck smear from a herpetic lesion will yield acantholytic, enlarged keratinocytes up to twice their usual size (referred to as ballooning degeneration), and multinucleation. In addition, molding of the nuclei to each other within the multinucleated cells and margination of the nuclear chromatin may be appreciated (Figure 2). Intranuclear inclusion bodies, also known as Cowdry type A bodies, can be seen that are nearly the size of red blood cells but are rare to find, with only 10% of specimens exhibiting this finding in a prospective review of 299 patients with herpetic vesiculobullous lesions.¹¹ Evaluation of the contents of blisters caused by bullous pemphigoid and erythema toxicum neonatorum may yield high densities of eosinophils with normal keratinocyte morphology (Figure 3). Other blistering eruptions such as pemphigus vulgaris and bullous drug eruptions also have characteristic findings.^1,2

Image courtesy of Aron Gewirtzman, MD (Austin, Texas).

Image courtesy of Rachel McAndrew, MD (Austin, Texas).

Gout Preparation

Gout is a systemic disease caused by uric acid accumulation that can present with joint pain and white to red nodules on digits, joints, and ears (known as tophi). Material may be expressed from tophi and examined immediately by polarized light microscopy to confirm the diagnosis.⁵ Specimens will demonstrate needle-shaped, negatively birefringent monosodium urate crystals on polarized light microscopy (Figure 4). An ordinary light microscope can be converted for such use with the lenses of inexpensive polarized sunglasses, placing one lens between the light source and specimen and the other lens between the examiner’s eye and the specimen.¹²

Image courtesy of Paul Massey, MD (Boston, Massachusetts).

Parasitic Infections

Two common parasitic infections identified in outpatient dermatology clinics are scabies mites and Demodex mites. Human scabies is extremely pruritic and caused by infestation with Sarcoptes scabiei var hominis; the typical presentation in an adult is erythematous and crusted papules, linear burrows, and vesiculopustules, especially of the interdigital spaces, wrists, axillae, umbilicus, and genital region.^1,13 Demodicidosis presents with papules and pustules on the face, usually in a patient with background rosacea and diffuse erythema.^1,5,14

If either of these conditions are suspected, mineral oil should be used to prepare the slide because it will maintain viability of the organisms, which are visualized better in motion. Adult scabies mites are roughly 10 times larger than keratinocytes, measuring approximately 250 to 450 µm in length with 8 legs.¹³ Eggs also may be visualized within the cellular debris and typically are 100 to 150 µm in size and ovoid in shape. Of note, polariscopic examination may be a useful adjunct for evaluation of scabies because scabetic spines and scybala (or fecal material) are polarizable.¹⁵

Two types of Demodex mites typically are found in the skin: Demodex folliculorum, which are similarly sized to scabies mites with a more oblong body and occur most commonly in mature hair follicles (eg, eyelashes), and Demodex brevis, which are about half the size (150–200 µm) and live in the sebaceous glands of vellus hairs (Figure 5).¹⁴ Both of these mites have 8 legs, similar to the scabies mite.

Image courtesy of Candelario Antonio Rodriguez Vivian, MD (Monterrey, Mexico).

Hair Preparations

Hair preparations for bulbar examination (eg, trichogram) may prove useful in the evaluation of many types of alopecia, and elaboration on this topic is beyond the scope of this article. Microscopic evaluation of the hair shaft may be an underutilized technique in the outpatient setting and is capable of yielding a variety of diagnoses, including monilethrix, pili torti, and pili trianguli et canaliculi, among others.³ One particularly useful scenario for hair shaft examination (usually of the eyebrow) is in the setting of a patient with severe atopic dermatitis or a baby with ichthyosiform erythroderma, as discovery of trichorrhexis invaginata is pathognomonic for the diagnosis of Netherton syndrome.¹⁶ Lastly, evaluation of the hair shaft in patients with patchy and diffuse hair loss whose clinical impression is reminiscent of alopecia areata, or those with concerns of inability to grow hair beyond a short length, may lead to diagnosis of loose anagen syndrome, especially if more than 70% of hair fibers examined exhibit the classic findings of a ruffled proximal cuticle and lack of root sheath.⁴

Final Thoughts

Bedside microscopy is a rapid and cost-sensitive way to confirm diagnoses that are clinically suspected and remains a valuable tool to acquire during residency training.

Dermatologists are uniquely equipped amongst clinicians to make bedside diagnoses because of the focus on histopathology and microscopy inherent in our training. This skill is highly valuable in both an inpatient and outpatient setting because it may lead to a rapid diagnosis or be a useful adjunct in the initial clinical decision-making process. Although expert microscopists may be able to garner relevant information from scraping almost any type of lesion, bedside microscopy primarily is used by dermatologists in the United States for consideration of infectious etiologies of a variety of cutaneous manifestations.^1,2

Basic Principles

Lesions that should be considered for bedside microscopic analysis in outpatient settings are scaly lesions, vesiculobullous lesions, inflammatory papules, and pustules¹; microscopic evaluation also can be useful for myriad trichoscopic considerations.^3,4 In some instances, direct visualization of the pathogen is possible (eg, cutaneous fungal infections, demodicidosis, scabetic infections), and in other circumstances reactive changes of keratinocytes or the presence of specific cell types can aid in diagnosis (eg, ballooning degeneration and multinucleation of keratinocytes in herpetic lesions, an abundance of eosinophils in erythema toxicum neonatorum). Different types of media are used to best prepare tissue based on the suspected etiology of the condition.

One major stumbling block for residents when beginning to perform bedside testing is the lack of dimensional understanding of the structures they are searching for; for example, medical students and residents often may mistake fibers for dermatophytes, which typically are much larger than fungal hyphae. Familiarizing oneself with the basic dimensions of different cell types or pathogens in relation to each other (Table) will help further refine the beginner’s ability to effectively search for and identify pathogenic features. This concept is further schematized in Figure 1 to help visualize scale differences.

Image courtesy of Bogdan Mohora, MS (Austin, Texas).

Examination of the Specimen

Slide preparation depends on the primary lesion in consideration and will be discussed in greater detail in the following sections. Once the slide is prepared, place it on the microscope stage and adjust the condenser and light source for optimal visualization. Scan the specimen in a gridlike fashion on low power (usually ×10) and then inspect suspicious findings on higher power (×40 or higher).

Dermatomycoses

Fungal infections of the skin can present as annular papulosquamous lesions, follicular pustules or papules, bullous lesions, hypopigmented patches, and mucosal exudate or erosions, among other manifestations.⁵ Potassium hydroxide (KOH) is the classic medium used in preparation of lesions being assessed for evidence of fungus because it leads to lysis of keratinocytes for better visualization of fungal hyphae and spores. Other media that contain KOH and additional substrates such as dimethyl sulfoxide or chlorazol black E can be used to better highlight fungal elements.⁶

Dermatophytosis
Dermatophytes lead to superficial infection of the epidermis and epidermal appendages and present in a variety of ways, including site-specific infections manifesting typically as erythematous, annular or arcuate scaling (eg, tinea faciei, tinea corporis, tinea cruris, tinea manus, tinea pedis), alopecia with broken hair shafts, black dots, boggy nodules and/or scaling of the scalp (eg, tinea capitis, favus, kerion), and dystrophic nails (eg, onychomycosis).^5,7 For examination of lesional skin scrapings, one can either use clear cellophane tape against the skin to remove scale, which is especially useful in the case of pediatric patients, and then press the tape against a slide prepared with several drops of a KOH-based medium to directly visualize without a coverslip, or scrape the lesion with a No. 15 blade and place the scales onto the glass slide, with further preparation as described below.⁸ For assessment of alopecia or dystrophic nails, scrape lesional skin with a No. 15 blade to obtain affected hair follicles and proximal subungual debris, respectively.^6,9

Once the cellular debris has been obtained and placed on the slide, a coverslip can be overlaid and KOH applied laterally to be taken up across the slide by capillary action. Allow the slide to sit for at least 5 minutes before analyzing to better visualize fungal elements. Both tinea and onychomycosis will show branching septate hyphae extending across keratinocytes; a common false-positive is identifying overlapping keratinocyte edges, which are a similar size, but they can be distinguished from fungi because they do not cross multiple keratinocytes.^1,8 Tinea capitis may demonstrate similar findings or may reveal hair shafts with spores contained within or surrounding it, corresponding to endothrix or ectothrix infection, respectively.⁵

Pityriasis Versicolor and Malassezia Folliculitis
Pityriasis versicolor presents with hypopigmented to pink, finely scaling ovoid papules, usually on the upper back, shoulders, and neck, and is caused by Malassezia furfur and other Malassezia species.⁵ Malassezia folliculitis also is caused by this fungus and presents with monomorphic follicular papules and pustules. Scrapings from the scaly papules will demonstrate keratinocytes with the classic “spaghetti and meatballs” fungal elements, whereas Malassezia folliculitis demonstrates only spores.^5,7

Candidiasis
One possible outpatient presentation of candidiasis is oral thrush, which can exhibit white mucosal exudate or erythematous patches. A tongue blade can be used to scrape the tongue or cheek wall, with subsequent preparatory steps with application of KOH as described for dermatophytes. Cutaneous candidiasis most often develops in intertriginous regions and will exhibit erosive painful lesions with satellite pustules. In both cases, analysis of the specimen will show shorter fatter hyphal elements than seen in dermatophytosis, with pseudohyphae, blunted ends, and potentially yeast forms.⁵

Vesiculobullous Lesions

The Tzanck smear has been used since the 1940s to differentiate between etiologies of blistering disorders and is now most commonly used for the quick identification of herpetic lesions.¹ The test is performed by scraping the base of a deroofed vesicle, pustule, or bulla, and smearing the cellular materials onto a glass slide. The most commonly utilized media for staining in the outpatient setting at my institution (University of Texas Dell Medical School, Austin) is Giemsa, which is composed of azure II–eosin, glycerin, and methanol. It stains nuclei a reddish blue to pink and the cytoplasm blue.¹⁰ After being applied to the slide, the cells are allowed to air-dry for 5 to 10 minutes, and Giemsa stain is subsequently applied and allowed to incubate for 15 minutes, then rinsed carefully with water and directly examined.

Other stains that can be used to perform the Tzanck smear include commercial preparations that may be more accessible in the inpatient settings such as the Wright-Giemsa, Quik-Dip, and Diff-Quick.^1,10

Examination of a Tzanck smear from a herpetic lesion will yield acantholytic, enlarged keratinocytes up to twice their usual size (referred to as ballooning degeneration), and multinucleation. In addition, molding of the nuclei to each other within the multinucleated cells and margination of the nuclear chromatin may be appreciated (Figure 2). Intranuclear inclusion bodies, also known as Cowdry type A bodies, can be seen that are nearly the size of red blood cells but are rare to find, with only 10% of specimens exhibiting this finding in a prospective review of 299 patients with herpetic vesiculobullous lesions.¹¹ Evaluation of the contents of blisters caused by bullous pemphigoid and erythema toxicum neonatorum may yield high densities of eosinophils with normal keratinocyte morphology (Figure 3). Other blistering eruptions such as pemphigus vulgaris and bullous drug eruptions also have characteristic findings.^1,2

Image courtesy of Aron Gewirtzman, MD (Austin, Texas).

Image courtesy of Rachel McAndrew, MD (Austin, Texas).

Gout Preparation

Gout is a systemic disease caused by uric acid accumulation that can present with joint pain and white to red nodules on digits, joints, and ears (known as tophi). Material may be expressed from tophi and examined immediately by polarized light microscopy to confirm the diagnosis.⁵ Specimens will demonstrate needle-shaped, negatively birefringent monosodium urate crystals on polarized light microscopy (Figure 4). An ordinary light microscope can be converted for such use with the lenses of inexpensive polarized sunglasses, placing one lens between the light source and specimen and the other lens between the examiner’s eye and the specimen.¹²

Image courtesy of Paul Massey, MD (Boston, Massachusetts).

Parasitic Infections

Two common parasitic infections identified in outpatient dermatology clinics are scabies mites and Demodex mites. Human scabies is extremely pruritic and caused by infestation with Sarcoptes scabiei var hominis; the typical presentation in an adult is erythematous and crusted papules, linear burrows, and vesiculopustules, especially of the interdigital spaces, wrists, axillae, umbilicus, and genital region.^1,13 Demodicidosis presents with papules and pustules on the face, usually in a patient with background rosacea and diffuse erythema.^1,5,14

If either of these conditions are suspected, mineral oil should be used to prepare the slide because it will maintain viability of the organisms, which are visualized better in motion. Adult scabies mites are roughly 10 times larger than keratinocytes, measuring approximately 250 to 450 µm in length with 8 legs.¹³ Eggs also may be visualized within the cellular debris and typically are 100 to 150 µm in size and ovoid in shape. Of note, polariscopic examination may be a useful adjunct for evaluation of scabies because scabetic spines and scybala (or fecal material) are polarizable.¹⁵

Two types of Demodex mites typically are found in the skin: Demodex folliculorum, which are similarly sized to scabies mites with a more oblong body and occur most commonly in mature hair follicles (eg, eyelashes), and Demodex brevis, which are about half the size (150–200 µm) and live in the sebaceous glands of vellus hairs (Figure 5).¹⁴ Both of these mites have 8 legs, similar to the scabies mite.

Image courtesy of Candelario Antonio Rodriguez Vivian, MD (Monterrey, Mexico).

Hair Preparations

Hair preparations for bulbar examination (eg, trichogram) may prove useful in the evaluation of many types of alopecia, and elaboration on this topic is beyond the scope of this article. Microscopic evaluation of the hair shaft may be an underutilized technique in the outpatient setting and is capable of yielding a variety of diagnoses, including monilethrix, pili torti, and pili trianguli et canaliculi, among others.³ One particularly useful scenario for hair shaft examination (usually of the eyebrow) is in the setting of a patient with severe atopic dermatitis or a baby with ichthyosiform erythroderma, as discovery of trichorrhexis invaginata is pathognomonic for the diagnosis of Netherton syndrome.¹⁶ Lastly, evaluation of the hair shaft in patients with patchy and diffuse hair loss whose clinical impression is reminiscent of alopecia areata, or those with concerns of inability to grow hair beyond a short length, may lead to diagnosis of loose anagen syndrome, especially if more than 70% of hair fibers examined exhibit the classic findings of a ruffled proximal cuticle and lack of root sheath.⁴

Final Thoughts

Bedside microscopy is a rapid and cost-sensitive way to confirm diagnoses that are clinically suspected and remains a valuable tool to acquire during residency training.

Dermatologists are uniquely equipped amongst clinicians to make bedside diagnoses because of the focus on histopathology and microscopy inherent in our training. This skill is highly valuable in both an inpatient and outpatient setting because it may lead to a rapid diagnosis or be a useful adjunct in the initial clinical decision-making process. Although expert microscopists may be able to garner relevant information from scraping almost any type of lesion, bedside microscopy primarily is used by dermatologists in the United States for consideration of infectious etiologies of a variety of cutaneous manifestations.^1,2

Basic Principles

Lesions that should be considered for bedside microscopic analysis in outpatient settings are scaly lesions, vesiculobullous lesions, inflammatory papules, and pustules¹; microscopic evaluation also can be useful for myriad trichoscopic considerations.^3,4 In some instances, direct visualization of the pathogen is possible (eg, cutaneous fungal infections, demodicidosis, scabetic infections), and in other circumstances reactive changes of keratinocytes or the presence of specific cell types can aid in diagnosis (eg, ballooning degeneration and multinucleation of keratinocytes in herpetic lesions, an abundance of eosinophils in erythema toxicum neonatorum). Different types of media are used to best prepare tissue based on the suspected etiology of the condition.

One major stumbling block for residents when beginning to perform bedside testing is the lack of dimensional understanding of the structures they are searching for; for example, medical students and residents often may mistake fibers for dermatophytes, which typically are much larger than fungal hyphae. Familiarizing oneself with the basic dimensions of different cell types or pathogens in relation to each other (Table) will help further refine the beginner’s ability to effectively search for and identify pathogenic features. This concept is further schematized in Figure 1 to help visualize scale differences.

Image courtesy of Bogdan Mohora, MS (Austin, Texas).

Examination of the Specimen

Slide preparation depends on the primary lesion in consideration and will be discussed in greater detail in the following sections. Once the slide is prepared, place it on the microscope stage and adjust the condenser and light source for optimal visualization. Scan the specimen in a gridlike fashion on low power (usually ×10) and then inspect suspicious findings on higher power (×40 or higher).

Dermatomycoses

Fungal infections of the skin can present as annular papulosquamous lesions, follicular pustules or papules, bullous lesions, hypopigmented patches, and mucosal exudate or erosions, among other manifestations.⁵ Potassium hydroxide (KOH) is the classic medium used in preparation of lesions being assessed for evidence of fungus because it leads to lysis of keratinocytes for better visualization of fungal hyphae and spores. Other media that contain KOH and additional substrates such as dimethyl sulfoxide or chlorazol black E can be used to better highlight fungal elements.⁶

Dermatophytosis
Dermatophytes lead to superficial infection of the epidermis and epidermal appendages and present in a variety of ways, including site-specific infections manifesting typically as erythematous, annular or arcuate scaling (eg, tinea faciei, tinea corporis, tinea cruris, tinea manus, tinea pedis), alopecia with broken hair shafts, black dots, boggy nodules and/or scaling of the scalp (eg, tinea capitis, favus, kerion), and dystrophic nails (eg, onychomycosis).^5,7 For examination of lesional skin scrapings, one can either use clear cellophane tape against the skin to remove scale, which is especially useful in the case of pediatric patients, and then press the tape against a slide prepared with several drops of a KOH-based medium to directly visualize without a coverslip, or scrape the lesion with a No. 15 blade and place the scales onto the glass slide, with further preparation as described below.⁸ For assessment of alopecia or dystrophic nails, scrape lesional skin with a No. 15 blade to obtain affected hair follicles and proximal subungual debris, respectively.^6,9

Once the cellular debris has been obtained and placed on the slide, a coverslip can be overlaid and KOH applied laterally to be taken up across the slide by capillary action. Allow the slide to sit for at least 5 minutes before analyzing to better visualize fungal elements. Both tinea and onychomycosis will show branching septate hyphae extending across keratinocytes; a common false-positive is identifying overlapping keratinocyte edges, which are a similar size, but they can be distinguished from fungi because they do not cross multiple keratinocytes.^1,8 Tinea capitis may demonstrate similar findings or may reveal hair shafts with spores contained within or surrounding it, corresponding to endothrix or ectothrix infection, respectively.⁵

Pityriasis Versicolor and Malassezia Folliculitis
Pityriasis versicolor presents with hypopigmented to pink, finely scaling ovoid papules, usually on the upper back, shoulders, and neck, and is caused by Malassezia furfur and other Malassezia species.⁵ Malassezia folliculitis also is caused by this fungus and presents with monomorphic follicular papules and pustules. Scrapings from the scaly papules will demonstrate keratinocytes with the classic “spaghetti and meatballs” fungal elements, whereas Malassezia folliculitis demonstrates only spores.^5,7

Candidiasis
One possible outpatient presentation of candidiasis is oral thrush, which can exhibit white mucosal exudate or erythematous patches. A tongue blade can be used to scrape the tongue or cheek wall, with subsequent preparatory steps with application of KOH as described for dermatophytes. Cutaneous candidiasis most often develops in intertriginous regions and will exhibit erosive painful lesions with satellite pustules. In both cases, analysis of the specimen will show shorter fatter hyphal elements than seen in dermatophytosis, with pseudohyphae, blunted ends, and potentially yeast forms.⁵

Vesiculobullous Lesions

The Tzanck smear has been used since the 1940s to differentiate between etiologies of blistering disorders and is now most commonly used for the quick identification of herpetic lesions.¹ The test is performed by scraping the base of a deroofed vesicle, pustule, or bulla, and smearing the cellular materials onto a glass slide. The most commonly utilized media for staining in the outpatient setting at my institution (University of Texas Dell Medical School, Austin) is Giemsa, which is composed of azure II–eosin, glycerin, and methanol. It stains nuclei a reddish blue to pink and the cytoplasm blue.¹⁰ After being applied to the slide, the cells are allowed to air-dry for 5 to 10 minutes, and Giemsa stain is subsequently applied and allowed to incubate for 15 minutes, then rinsed carefully with water and directly examined.

Other stains that can be used to perform the Tzanck smear include commercial preparations that may be more accessible in the inpatient settings such as the Wright-Giemsa, Quik-Dip, and Diff-Quick.^1,10

Examination of a Tzanck smear from a herpetic lesion will yield acantholytic, enlarged keratinocytes up to twice their usual size (referred to as ballooning degeneration), and multinucleation. In addition, molding of the nuclei to each other within the multinucleated cells and margination of the nuclear chromatin may be appreciated (Figure 2). Intranuclear inclusion bodies, also known as Cowdry type A bodies, can be seen that are nearly the size of red blood cells but are rare to find, with only 10% of specimens exhibiting this finding in a prospective review of 299 patients with herpetic vesiculobullous lesions.¹¹ Evaluation of the contents of blisters caused by bullous pemphigoid and erythema toxicum neonatorum may yield high densities of eosinophils with normal keratinocyte morphology (Figure 3). Other blistering eruptions such as pemphigus vulgaris and bullous drug eruptions also have characteristic findings.^1,2

Image courtesy of Aron Gewirtzman, MD (Austin, Texas).

Image courtesy of Rachel McAndrew, MD (Austin, Texas).

Gout Preparation

Gout is a systemic disease caused by uric acid accumulation that can present with joint pain and white to red nodules on digits, joints, and ears (known as tophi). Material may be expressed from tophi and examined immediately by polarized light microscopy to confirm the diagnosis.⁵ Specimens will demonstrate needle-shaped, negatively birefringent monosodium urate crystals on polarized light microscopy (Figure 4). An ordinary light microscope can be converted for such use with the lenses of inexpensive polarized sunglasses, placing one lens between the light source and specimen and the other lens between the examiner’s eye and the specimen.¹²

Image courtesy of Paul Massey, MD (Boston, Massachusetts).

Parasitic Infections

Two common parasitic infections identified in outpatient dermatology clinics are scabies mites and Demodex mites. Human scabies is extremely pruritic and caused by infestation with Sarcoptes scabiei var hominis; the typical presentation in an adult is erythematous and crusted papules, linear burrows, and vesiculopustules, especially of the interdigital spaces, wrists, axillae, umbilicus, and genital region.^1,13 Demodicidosis presents with papules and pustules on the face, usually in a patient with background rosacea and diffuse erythema.^1,5,14

If either of these conditions are suspected, mineral oil should be used to prepare the slide because it will maintain viability of the organisms, which are visualized better in motion. Adult scabies mites are roughly 10 times larger than keratinocytes, measuring approximately 250 to 450 µm in length with 8 legs.¹³ Eggs also may be visualized within the cellular debris and typically are 100 to 150 µm in size and ovoid in shape. Of note, polariscopic examination may be a useful adjunct for evaluation of scabies because scabetic spines and scybala (or fecal material) are polarizable.¹⁵

Two types of Demodex mites typically are found in the skin: Demodex folliculorum, which are similarly sized to scabies mites with a more oblong body and occur most commonly in mature hair follicles (eg, eyelashes), and Demodex brevis, which are about half the size (150–200 µm) and live in the sebaceous glands of vellus hairs (Figure 5).¹⁴ Both of these mites have 8 legs, similar to the scabies mite.

Image courtesy of Candelario Antonio Rodriguez Vivian, MD (Monterrey, Mexico).

Hair Preparations

Hair preparations for bulbar examination (eg, trichogram) may prove useful in the evaluation of many types of alopecia, and elaboration on this topic is beyond the scope of this article. Microscopic evaluation of the hair shaft may be an underutilized technique in the outpatient setting and is capable of yielding a variety of diagnoses, including monilethrix, pili torti, and pili trianguli et canaliculi, among others.³ One particularly useful scenario for hair shaft examination (usually of the eyebrow) is in the setting of a patient with severe atopic dermatitis or a baby with ichthyosiform erythroderma, as discovery of trichorrhexis invaginata is pathognomonic for the diagnosis of Netherton syndrome.¹⁶ Lastly, evaluation of the hair shaft in patients with patchy and diffuse hair loss whose clinical impression is reminiscent of alopecia areata, or those with concerns of inability to grow hair beyond a short length, may lead to diagnosis of loose anagen syndrome, especially if more than 70% of hair fibers examined exhibit the classic findings of a ruffled proximal cuticle and lack of root sheath.⁴

Final Thoughts

Bedside microscopy is a rapid and cost-sensitive way to confirm diagnoses that are clinically suspected and remains a valuable tool to acquire during residency training.

The Diagnosis: Bowenoid Papulosis 

A 4-mm punch biopsy was performed from the active border of brown plaques on the dorsal penis. Histopathology revealed parakeratotic hyperkeratosis, acanthosis, loss of maturation in epithelium, and full-size atypia (Figure 1). Ki-67 index was 90% positive in the epidermis (Figure 2). Staining for p16 and human papillomavirus (HPV) screening was positive for HPV type 16 (Figure 3). Serologic tests for other sexually transmitted infections were negative. A diagnosis of penile bowenoid papulosis (BP) with grade 3 penile intraepithelial neoplasia was made, and treatment with topical 5-fluorouracil (5-FU) was initiated. Almost total regression was appreciated at 1-month follow-up (Figure 4), and he also was recurrence free at 1-year follow-up.

Penile intraepithelial neoplasia (PIN), or penile squamous cell carcinoma in situ, is a rare disease with high morbidity and mortality rates. Clinically, PIN is comprised of a clinical spectrum including 3 different entities: erythroplasia of Queyrat, Bowen disease, and BP.¹ Histologically, PIN also is classified into 3 subtypes according to histological depth of epidermal atypia.¹

Bowenoid papulosis usually is characterized by multiple red-brown or flesh-colored papules that most commonly appear on the shaft or glans of the penis. Bowenoid papulosis frequently is associated with high-risk types of HPV, such as HPV type 16, and is sometimes difficult to differentiate clinically from pigmented condyloma acuminatum. The clinical lesions of BP usually are less papillomatous, smoother topped, more polymorphic, and more coalescent compared to common genital viral condyloma acuminatum.² Bowenoid papulosis usually is seen in young (<30 years of age) sexually active men, unlike the patches or plaques of erythroplasia of Queyrat or Bowen disease, which are seen in older men aged 45 to 75 years. Bowenoid papulosis also has a lower malignancy potential than erythroplasia of Queyrat and Bowen disease.²

Penile melanosis, penile lentigo, and seborrheic keratosis comprise the differential diagnosis of dark spots on the penis and also should be kept in mind. Penile melanosis is the most common cause of dark spots on the penis. When the dark spots have irregular borders and change in color, they may be misdiagnosed as malignant lesions such as melanoma.³ In most cases, biopsy is indicated. Histologically, penile melanosis is characterized by hyperpigmentation of the basal cell layer with no melanocytic hyperplasia. Treatment is unnecessary in most cases.

Penile lentigo presents as small flat pigmented spots on the penile skin with clearly defined margins surrounded by normal-appearing skin. Histologically, it is characterized by hyperplasia of melanocytes above the basement membrane of the epidermis.³

Penile pigmented seborrheic keratosis is a rare clinical entity that can be easily misinterpreted as condyloma acuminatum. Histologically, it is characterized by basal cell hyperplasia with cystic formation in the thickened epidermis. Excisional biopsy may be the only way to rule out malignant disease.

Treatment options for PIN include cryotherapy, CO₂ or Nd:YAG lasers, photodynamic therapy, topical 5-FU or imiquimod therapy, and surgical excision such as Mohs micrographic surgery.^4-9 Although these therapeutic modalities usually are effective, recurrence is common.⁶ The patients' discomfort and poor cosmetic and functional outcomes from the surgical removal of lesions also present a challenge in treatment planning. 

In our patient, we quickly achieved a good result with topical 5-FU, though the disease was in local advanced stage. It is important for clinicians to consider 5-FU as an effective treatment option for PIN before planning surgery.

The Diagnosis: Bowenoid Papulosis 

A 4-mm punch biopsy was performed from the active border of brown plaques on the dorsal penis. Histopathology revealed parakeratotic hyperkeratosis, acanthosis, loss of maturation in epithelium, and full-size atypia (Figure 1). Ki-67 index was 90% positive in the epidermis (Figure 2). Staining for p16 and human papillomavirus (HPV) screening was positive for HPV type 16 (Figure 3). Serologic tests for other sexually transmitted infections were negative. A diagnosis of penile bowenoid papulosis (BP) with grade 3 penile intraepithelial neoplasia was made, and treatment with topical 5-fluorouracil (5-FU) was initiated. Almost total regression was appreciated at 1-month follow-up (Figure 4), and he also was recurrence free at 1-year follow-up.

Penile intraepithelial neoplasia (PIN), or penile squamous cell carcinoma in situ, is a rare disease with high morbidity and mortality rates. Clinically, PIN is comprised of a clinical spectrum including 3 different entities: erythroplasia of Queyrat, Bowen disease, and BP.¹ Histologically, PIN also is classified into 3 subtypes according to histological depth of epidermal atypia.¹

Bowenoid papulosis usually is characterized by multiple red-brown or flesh-colored papules that most commonly appear on the shaft or glans of the penis. Bowenoid papulosis frequently is associated with high-risk types of HPV, such as HPV type 16, and is sometimes difficult to differentiate clinically from pigmented condyloma acuminatum. The clinical lesions of BP usually are less papillomatous, smoother topped, more polymorphic, and more coalescent compared to common genital viral condyloma acuminatum.² Bowenoid papulosis usually is seen in young (<30 years of age) sexually active men, unlike the patches or plaques of erythroplasia of Queyrat or Bowen disease, which are seen in older men aged 45 to 75 years. Bowenoid papulosis also has a lower malignancy potential than erythroplasia of Queyrat and Bowen disease.²

Penile melanosis, penile lentigo, and seborrheic keratosis comprise the differential diagnosis of dark spots on the penis and also should be kept in mind. Penile melanosis is the most common cause of dark spots on the penis. When the dark spots have irregular borders and change in color, they may be misdiagnosed as malignant lesions such as melanoma.³ In most cases, biopsy is indicated. Histologically, penile melanosis is characterized by hyperpigmentation of the basal cell layer with no melanocytic hyperplasia. Treatment is unnecessary in most cases.

Penile lentigo presents as small flat pigmented spots on the penile skin with clearly defined margins surrounded by normal-appearing skin. Histologically, it is characterized by hyperplasia of melanocytes above the basement membrane of the epidermis.³

Penile pigmented seborrheic keratosis is a rare clinical entity that can be easily misinterpreted as condyloma acuminatum. Histologically, it is characterized by basal cell hyperplasia with cystic formation in the thickened epidermis. Excisional biopsy may be the only way to rule out malignant disease.

Treatment options for PIN include cryotherapy, CO₂ or Nd:YAG lasers, photodynamic therapy, topical 5-FU or imiquimod therapy, and surgical excision such as Mohs micrographic surgery.^4-9 Although these therapeutic modalities usually are effective, recurrence is common.⁶ The patients' discomfort and poor cosmetic and functional outcomes from the surgical removal of lesions also present a challenge in treatment planning. 

In our patient, we quickly achieved a good result with topical 5-FU, though the disease was in local advanced stage. It is important for clinicians to consider 5-FU as an effective treatment option for PIN before planning surgery.

The Diagnosis: Bowenoid Papulosis 

A 4-mm punch biopsy was performed from the active border of brown plaques on the dorsal penis. Histopathology revealed parakeratotic hyperkeratosis, acanthosis, loss of maturation in epithelium, and full-size atypia (Figure 1). Ki-67 index was 90% positive in the epidermis (Figure 2). Staining for p16 and human papillomavirus (HPV) screening was positive for HPV type 16 (Figure 3). Serologic tests for other sexually transmitted infections were negative. A diagnosis of penile bowenoid papulosis (BP) with grade 3 penile intraepithelial neoplasia was made, and treatment with topical 5-fluorouracil (5-FU) was initiated. Almost total regression was appreciated at 1-month follow-up (Figure 4), and he also was recurrence free at 1-year follow-up.

Penile intraepithelial neoplasia (PIN), or penile squamous cell carcinoma in situ, is a rare disease with high morbidity and mortality rates. Clinically, PIN is comprised of a clinical spectrum including 3 different entities: erythroplasia of Queyrat, Bowen disease, and BP.¹ Histologically, PIN also is classified into 3 subtypes according to histological depth of epidermal atypia.¹

Bowenoid papulosis usually is characterized by multiple red-brown or flesh-colored papules that most commonly appear on the shaft or glans of the penis. Bowenoid papulosis frequently is associated with high-risk types of HPV, such as HPV type 16, and is sometimes difficult to differentiate clinically from pigmented condyloma acuminatum. The clinical lesions of BP usually are less papillomatous, smoother topped, more polymorphic, and more coalescent compared to common genital viral condyloma acuminatum.² Bowenoid papulosis usually is seen in young (<30 years of age) sexually active men, unlike the patches or plaques of erythroplasia of Queyrat or Bowen disease, which are seen in older men aged 45 to 75 years. Bowenoid papulosis also has a lower malignancy potential than erythroplasia of Queyrat and Bowen disease.²

Penile melanosis, penile lentigo, and seborrheic keratosis comprise the differential diagnosis of dark spots on the penis and also should be kept in mind. Penile melanosis is the most common cause of dark spots on the penis. When the dark spots have irregular borders and change in color, they may be misdiagnosed as malignant lesions such as melanoma.³ In most cases, biopsy is indicated. Histologically, penile melanosis is characterized by hyperpigmentation of the basal cell layer with no melanocytic hyperplasia. Treatment is unnecessary in most cases.

Penile lentigo presents as small flat pigmented spots on the penile skin with clearly defined margins surrounded by normal-appearing skin. Histologically, it is characterized by hyperplasia of melanocytes above the basement membrane of the epidermis.³

Penile pigmented seborrheic keratosis is a rare clinical entity that can be easily misinterpreted as condyloma acuminatum. Histologically, it is characterized by basal cell hyperplasia with cystic formation in the thickened epidermis. Excisional biopsy may be the only way to rule out malignant disease.

Treatment options for PIN include cryotherapy, CO₂ or Nd:YAG lasers, photodynamic therapy, topical 5-FU or imiquimod therapy, and surgical excision such as Mohs micrographic surgery.^4-9 Although these therapeutic modalities usually are effective, recurrence is common.⁶ The patients' discomfort and poor cosmetic and functional outcomes from the surgical removal of lesions also present a challenge in treatment planning. 

In our patient, we quickly achieved a good result with topical 5-FU, though the disease was in local advanced stage. It is important for clinicians to consider 5-FU as an effective treatment option for PIN before planning surgery.

The Diagnosis: Eruptive Blue Nevus

All biopsies demonstrated similar histologic features, including an intradermal proliferation of heavily pigmented, spindle-shaped dendritic melanocytes (Figure). The dermal pigment was most pronounced in the grossly darker papules, and there was not a substantial amount of background pigmentation at the stratum basale. Cytologic atypia, foci of necrosis, and mitotic activity were absent from all sections. There was no definitive junctional component identified, no multinucleated giant cells, and there was no overlying epidermal aberration. With some background pigmentation seen histologically, nevus spilus was considered, but because this acute eruption occurred in a young adult without appreciable gross background hyperpigmentation, the clinical context led to a diagnosis of eruptive blue nevus. After communicating the findings to the patient, he declined further treatment.

Eruptive blue nevus is an exceptionally rare subtype of blue nevus with few cases reported since the 1940s.^1-9 Generally, each case report found a triggering event that could possibly have precipitated the acute proliferation and evolution of nevi. Triggering events can include bullous processes such as erythema multiforme² and Stevens-Johnson syndrome,³ severe sunburn,⁴ trauma,⁵ immunosuppression,⁶ and a variety of endocrinopathies. No such history could be identified in our patient, except the biopsy.

Common blue nevi are benign, usually congenital, well-circumscribed, solitary, blue-gray macules or papules. Half of blue nevi cases are found on the dorsal aspects of the hands and feet but can present anywhere (eg, face, scalp, wrists, sacrum, buttocks). The blue-gray color appreciated clinically is attributed to the Tyndall effect, which occurs when long-wavelength light--red, orange, and yellow--is absorbed by the melanin deep in the dermis, while short-wavelength visible light--blue, violet, and indigo--is reflected with backscattering. On polarized dermoscopy, a homogeneous blue-gray hue is appreciated, but lighter segments may be present when collagen deposition is robust. Histopathologic findings confirm spindle-shaped dendritic melanocytes in the dermis without epidermal involvement. It generally is accepted that the etiology of these benign nevi is a failed migration of neural crest cells to the epidermis.^10,11 Although the common blue nevus may be simple to diagnose, several subtypes have been described in the literature, including combined blue nevus, desmoplastic blue nevus, hypomelanotic/amelanotic blue nevus, and epithelioid blue nevus of Carney complex, and excluding a malignant process is of monumental importance.^7,12

Biopsy is recommended for common blue nevi in the evaluation of newly acquired lesions, expansion of previously stable nevi, or for nevi larger than 10 mm in diameter. The nature of eruptive blue nevi warrants a biopsy to exclude melanoma or another malignant process. While the Becker nevus may manifest in adolescent males, it is clinically distinct from an eruptive blue nevus due to the size, relative homogeneity, and presence of hair within the lesion. Cutaneous amyloidosis may appear clinically similar to an eruptive blue nevus, but globular or amorphous material was not present in the papillary dermis of biopsied lesions in our patient. Since there was no cellular atypia or mitotic activity, melanoma and other malignancies were ruled out. Lastly, NAME syndrome by definition must include atrial myxomas, myxoid neurofibromas, and ephelides in addition to the nevi; however, our patient had only nevi and few ephelides. Once the diagnosis is established and benign nature confirmed, treatment is not necessarily required. If the patient elects to remove the lesion for aesthetic reasons, an excision into the subcutaneous fat is required to ensure complete removal of deep dermal melanocytes. Prior excisions of eruptive blue nevi have had no recurrence after more than 10 months.^8,9

The Diagnosis: Eruptive Blue Nevus

All biopsies demonstrated similar histologic features, including an intradermal proliferation of heavily pigmented, spindle-shaped dendritic melanocytes (Figure). The dermal pigment was most pronounced in the grossly darker papules, and there was not a substantial amount of background pigmentation at the stratum basale. Cytologic atypia, foci of necrosis, and mitotic activity were absent from all sections. There was no definitive junctional component identified, no multinucleated giant cells, and there was no overlying epidermal aberration. With some background pigmentation seen histologically, nevus spilus was considered, but because this acute eruption occurred in a young adult without appreciable gross background hyperpigmentation, the clinical context led to a diagnosis of eruptive blue nevus. After communicating the findings to the patient, he declined further treatment.

Eruptive blue nevus is an exceptionally rare subtype of blue nevus with few cases reported since the 1940s.^1-9 Generally, each case report found a triggering event that could possibly have precipitated the acute proliferation and evolution of nevi. Triggering events can include bullous processes such as erythema multiforme² and Stevens-Johnson syndrome,³ severe sunburn,⁴ trauma,⁵ immunosuppression,⁶ and a variety of endocrinopathies. No such history could be identified in our patient, except the biopsy.

Common blue nevi are benign, usually congenital, well-circumscribed, solitary, blue-gray macules or papules. Half of blue nevi cases are found on the dorsal aspects of the hands and feet but can present anywhere (eg, face, scalp, wrists, sacrum, buttocks). The blue-gray color appreciated clinically is attributed to the Tyndall effect, which occurs when long-wavelength light--red, orange, and yellow--is absorbed by the melanin deep in the dermis, while short-wavelength visible light--blue, violet, and indigo--is reflected with backscattering. On polarized dermoscopy, a homogeneous blue-gray hue is appreciated, but lighter segments may be present when collagen deposition is robust. Histopathologic findings confirm spindle-shaped dendritic melanocytes in the dermis without epidermal involvement. It generally is accepted that the etiology of these benign nevi is a failed migration of neural crest cells to the epidermis.^10,11 Although the common blue nevus may be simple to diagnose, several subtypes have been described in the literature, including combined blue nevus, desmoplastic blue nevus, hypomelanotic/amelanotic blue nevus, and epithelioid blue nevus of Carney complex, and excluding a malignant process is of monumental importance.^7,12

Biopsy is recommended for common blue nevi in the evaluation of newly acquired lesions, expansion of previously stable nevi, or for nevi larger than 10 mm in diameter. The nature of eruptive blue nevi warrants a biopsy to exclude melanoma or another malignant process. While the Becker nevus may manifest in adolescent males, it is clinically distinct from an eruptive blue nevus due to the size, relative homogeneity, and presence of hair within the lesion. Cutaneous amyloidosis may appear clinically similar to an eruptive blue nevus, but globular or amorphous material was not present in the papillary dermis of biopsied lesions in our patient. Since there was no cellular atypia or mitotic activity, melanoma and other malignancies were ruled out. Lastly, NAME syndrome by definition must include atrial myxomas, myxoid neurofibromas, and ephelides in addition to the nevi; however, our patient had only nevi and few ephelides. Once the diagnosis is established and benign nature confirmed, treatment is not necessarily required. If the patient elects to remove the lesion for aesthetic reasons, an excision into the subcutaneous fat is required to ensure complete removal of deep dermal melanocytes. Prior excisions of eruptive blue nevi have had no recurrence after more than 10 months.^8,9

The Diagnosis: Eruptive Blue Nevus

All biopsies demonstrated similar histologic features, including an intradermal proliferation of heavily pigmented, spindle-shaped dendritic melanocytes (Figure). The dermal pigment was most pronounced in the grossly darker papules, and there was not a substantial amount of background pigmentation at the stratum basale. Cytologic atypia, foci of necrosis, and mitotic activity were absent from all sections. There was no definitive junctional component identified, no multinucleated giant cells, and there was no overlying epidermal aberration. With some background pigmentation seen histologically, nevus spilus was considered, but because this acute eruption occurred in a young adult without appreciable gross background hyperpigmentation, the clinical context led to a diagnosis of eruptive blue nevus. After communicating the findings to the patient, he declined further treatment.

Eruptive blue nevus is an exceptionally rare subtype of blue nevus with few cases reported since the 1940s.^1-9 Generally, each case report found a triggering event that could possibly have precipitated the acute proliferation and evolution of nevi. Triggering events can include bullous processes such as erythema multiforme² and Stevens-Johnson syndrome,³ severe sunburn,⁴ trauma,⁵ immunosuppression,⁶ and a variety of endocrinopathies. No such history could be identified in our patient, except the biopsy.

Common blue nevi are benign, usually congenital, well-circumscribed, solitary, blue-gray macules or papules. Half of blue nevi cases are found on the dorsal aspects of the hands and feet but can present anywhere (eg, face, scalp, wrists, sacrum, buttocks). The blue-gray color appreciated clinically is attributed to the Tyndall effect, which occurs when long-wavelength light--red, orange, and yellow--is absorbed by the melanin deep in the dermis, while short-wavelength visible light--blue, violet, and indigo--is reflected with backscattering. On polarized dermoscopy, a homogeneous blue-gray hue is appreciated, but lighter segments may be present when collagen deposition is robust. Histopathologic findings confirm spindle-shaped dendritic melanocytes in the dermis without epidermal involvement. It generally is accepted that the etiology of these benign nevi is a failed migration of neural crest cells to the epidermis.^10,11 Although the common blue nevus may be simple to diagnose, several subtypes have been described in the literature, including combined blue nevus, desmoplastic blue nevus, hypomelanotic/amelanotic blue nevus, and epithelioid blue nevus of Carney complex, and excluding a malignant process is of monumental importance.^7,12

Biopsy is recommended for common blue nevi in the evaluation of newly acquired lesions, expansion of previously stable nevi, or for nevi larger than 10 mm in diameter. The nature of eruptive blue nevi warrants a biopsy to exclude melanoma or another malignant process. While the Becker nevus may manifest in adolescent males, it is clinically distinct from an eruptive blue nevus due to the size, relative homogeneity, and presence of hair within the lesion. Cutaneous amyloidosis may appear clinically similar to an eruptive blue nevus, but globular or amorphous material was not present in the papillary dermis of biopsied lesions in our patient. Since there was no cellular atypia or mitotic activity, melanoma and other malignancies were ruled out. Lastly, NAME syndrome by definition must include atrial myxomas, myxoid neurofibromas, and ephelides in addition to the nevi; however, our patient had only nevi and few ephelides. Once the diagnosis is established and benign nature confirmed, treatment is not necessarily required. If the patient elects to remove the lesion for aesthetic reasons, an excision into the subcutaneous fat is required to ensure complete removal of deep dermal melanocytes. Prior excisions of eruptive blue nevi have had no recurrence after more than 10 months.^8,9

The cutaneous manifestations of Crohn disease (CD) are varied, including pyoderma gangrenosum, erythema nodosum, and metastatic CD (MCD). First described by Parks et al,¹ MCD is defined as the occurrence of granulomatous lesions at a skin site distant from the gastrointestinal tract.^1-20 Metastatic CD presents a diagnostic challenge because it is a rare component in the spectrum of inflammatory bowel disease complications, and many physicians are unaware of its existence. It may precede, coincide with, or develop after the diagnosis of intestinal disease.^2-5 Vulvoperineal involvement is particularly problematic because a multitude of other, more likely disease processes are considered first. Typically it is initially diagnosed as a presumed infection prompting reflexive treatment with antivirals, antifungals, and antibiotics. Patients may experience symptoms for years prior to correct diagnosis and institution of proper therapy. A variety of clinical presentations have been described, including nonspecific pain and swelling, erythematous papules and plaques, and nonhealing ulcers. Skin biopsy characteristically confirms the diagnosis and reveals dermal noncaseating granulomas. Multiple oral and parenteral therapies are available, with surgical intervention reserved for resistant cases. We present a case of vulvovaginal MCD in the setting of well-controlled intestinal disease. We also provide a review of the literature regarding genital CD and emphasize the need to keep MCD in the differential of vulvoperineal pathology.

Case Report

A 29-year-old woman was referred to the dermatology clinic with vulvar pain, swelling, and pruritus of 14 months’ duration. Her medical history was remarkable for CD following a colectomy with colostomy. Prior therapies included methotrexate with infliximab for 5 years followed by a 2-year regimen with adalimumab, which induced remission of the intestinal disease.

The patient previously had taken a variety of topical and oral antimicrobials based on treatment from a primary care physician because fungal, bacterial, and viral infections initially were suspected; however, the vulvar disease persisted, and drug-induced immunosuppression was considered to be an underlying factor. Thus, adalimumab was discontinued. Despite elimination of the biologic, the vulvar disease progressed, which prompted referral to the dermatology clinic.

Physical examination revealed diffuse vulvar edema with overlying erythema and scale (Figure 1A). Upon closer inspection, scattered violaceous papules atop a backdrop of lichenification were evident, imparting a cobblestone appearance (Figure 1B). Additionally, a fissure was present on the gluteal cleft. Biopsy from the left labia majora demonstrated well-formed granulomas within a fibrotic reticular dermis (Figures 2A and 2B). The granulomas consisted of both mononucleated and multinucleated histiocytes, rimmed peripherally by lymphocytes and plasma cells (Figure 2C). Periodic acid–Schiff–diastase and acid-fast bacilli stains as well as polarizing microscopy were negative.

Comment

Crohn disease is an idiopathic chronic inflammatory condition that primarily affects the gastrointestinal tract, anywhere from the mouth to the anus. It is characterized by transmural inflammation and fissures that can extend beyond the muscularis propria.^4,6 Extraintestinal manifestations are common.³

Cutaneous CD often presents as perianal, perifistular, or peristomal inflammation or ulceration.⁷ Other skin manifestations include pyoderma gangrenosum, erythema nodosum, erythema multiforme, epidermolysis bullosa acquisita, and palmar erythema.⁷ Metastatic CD involves skin noncontiguous with the gastrointestinal tract^1-20 and may involve any portion of the cutis. Although rare, MCD is the typical etiology underlying vulvar CD.⁸

Approximately 20% of MCD patients have cutaneous lesions without a history of gastrointestinal disease. More than half of cases in adults and approximately two-thirds in children involve the genitalia. Although more common in adults, vulvar involvement has been reported in children as young as 6 years of age.² Diagnosis is especially challenging when bowel symptoms are absent; those patients should be evaluated and followed for subsequent intestinal involvement.⁶

Clinically, symptoms may include general discomfort, pain, pruritus, and dyspareunia. Psychosocial and sexual dysfunction are prevalent and also should be addressed.⁹ Depending on the stage of the disease, physical examination may reveal erythema, edema, papules, pustules, nodules, condylomatous lesions, abscesses, fissures, fistulas, ulceration, acrochordons, and scarring.^2-6,10,11

A host of infections (ie, mycobacterial, actinomycosis, deep fungal, sexually transmitted, schistosomiasis), inflammatory conditions (ie, sarcoid, hidradenitis suppurativa), foreign body reactions, Melkersson-Rosenthal syndrome, and sexual abuse should be included in the differential diagnosis.^2,6,10-12 Once infection, sarcoid, and foreign body reaction have been ruled out, noncaseating granulomas in skin are highly suggestive of CD.⁷

Histopathologic findings of MCD reveal myriad morphological reaction patterns,^5,13 including high-grade dysplasia and carcinoma of the vulva; therefore, it may be imprudent to withhold diagnosis based on the absence of the historically pathognomonic noncaseating granulomas.⁵

The etiopathogenesis of MCD remains an enigma. Dermatopathologic examinations consistently reveal a vascular injury syndrome,¹³ implicating a possible circulatory system contribution via deposition of immune complexes or antigens in skin.⁷ Bacterial infection has been implicated in the intestinal manifestations of CD; however, failure to detect microbial ribosomal RNA in MCD biopsies refutes theories of hematogenous spread of microbes.¹³ Another plausible explanation is that antibodies are formed to conserved microbial epitopes following loss of tolerance to gut flora, which results in an excessive immunologic response at distinct sites in susceptible individuals.¹³ A T-lymphocyte–mediated type IV hypersensitivity reaction also has been proposed via cross-reactivity of lymphocytes, with skin antigens precipitating extraintestinal granuloma formation and vascular injury.³ Clearly, further investigation is needed.

Magnetic resonanance imaging can identify the extent and anatomy of intestinal and pelvic disease and can assist in the diagnosis of vulvar CD.^10,11,14 For these reasons, some experts propose that imaging should be instituted prior to therapy,^12,15,16 especially when direct extension is suspected.¹⁷

Treatment is challenging and often involves collaboration among several specialties.¹² Many treatment options exist because therapeutic responses vary and genital MCD is frequently recalcitrant to therapy.⁴ Medical therapy includes antibiotics such as metronidazole, corticosteroids (ie, topical, intralesional, systemic), and immune modulators (eg, azathioprine, 6-mercaptopurine, cyclosporine, methotrexate, mycophenolate mofetil, tumor necrosis factor α inhibitors).^{2,3,6,10,16,18} Thalidomide has been used for refractory cases.¹⁹ These treatments can be used alone or in combination. Patients should be monitored for side effects and informed that many treatment regimens may be required before a sustained response is achieved.^4,16,18 Surgery is reserved for the most resistant cases. Extensive radical excision of the involved area is the best approach, as limited local excision often is followed by recurrence.²⁰

Conclusion

Our case highlights that vulvar CD can develop in the setting of well-controlled intestinal disease. Vulvoperineal CD should be considered in the differential diagnosis of chronic vulvar pain, swelling, and pruritus, especially in cases resistant to standard therapies and regardless of whether or not gastrointestinal tract symptoms are present. Physicians must be cognizant that vulvar signs and symptoms may precede, coincide with, or follow the diagnosis of intestinal CD. Increased awareness of this entity may facilitate its early recognition and prompt more timely treatment among women with vulvar disease caused by MCD.

The cutaneous manifestations of Crohn disease (CD) are varied, including pyoderma gangrenosum, erythema nodosum, and metastatic CD (MCD). First described by Parks et al,¹ MCD is defined as the occurrence of granulomatous lesions at a skin site distant from the gastrointestinal tract.^1-20 Metastatic CD presents a diagnostic challenge because it is a rare component in the spectrum of inflammatory bowel disease complications, and many physicians are unaware of its existence. It may precede, coincide with, or develop after the diagnosis of intestinal disease.^2-5 Vulvoperineal involvement is particularly problematic because a multitude of other, more likely disease processes are considered first. Typically it is initially diagnosed as a presumed infection prompting reflexive treatment with antivirals, antifungals, and antibiotics. Patients may experience symptoms for years prior to correct diagnosis and institution of proper therapy. A variety of clinical presentations have been described, including nonspecific pain and swelling, erythematous papules and plaques, and nonhealing ulcers. Skin biopsy characteristically confirms the diagnosis and reveals dermal noncaseating granulomas. Multiple oral and parenteral therapies are available, with surgical intervention reserved for resistant cases. We present a case of vulvovaginal MCD in the setting of well-controlled intestinal disease. We also provide a review of the literature regarding genital CD and emphasize the need to keep MCD in the differential of vulvoperineal pathology.

Case Report

A 29-year-old woman was referred to the dermatology clinic with vulvar pain, swelling, and pruritus of 14 months’ duration. Her medical history was remarkable for CD following a colectomy with colostomy. Prior therapies included methotrexate with infliximab for 5 years followed by a 2-year regimen with adalimumab, which induced remission of the intestinal disease.

The patient previously had taken a variety of topical and oral antimicrobials based on treatment from a primary care physician because fungal, bacterial, and viral infections initially were suspected; however, the vulvar disease persisted, and drug-induced immunosuppression was considered to be an underlying factor. Thus, adalimumab was discontinued. Despite elimination of the biologic, the vulvar disease progressed, which prompted referral to the dermatology clinic.

Physical examination revealed diffuse vulvar edema with overlying erythema and scale (Figure 1A). Upon closer inspection, scattered violaceous papules atop a backdrop of lichenification were evident, imparting a cobblestone appearance (Figure 1B). Additionally, a fissure was present on the gluteal cleft. Biopsy from the left labia majora demonstrated well-formed granulomas within a fibrotic reticular dermis (Figures 2A and 2B). The granulomas consisted of both mononucleated and multinucleated histiocytes, rimmed peripherally by lymphocytes and plasma cells (Figure 2C). Periodic acid–Schiff–diastase and acid-fast bacilli stains as well as polarizing microscopy were negative.

Comment

Crohn disease is an idiopathic chronic inflammatory condition that primarily affects the gastrointestinal tract, anywhere from the mouth to the anus. It is characterized by transmural inflammation and fissures that can extend beyond the muscularis propria.^4,6 Extraintestinal manifestations are common.³

Cutaneous CD often presents as perianal, perifistular, or peristomal inflammation or ulceration.⁷ Other skin manifestations include pyoderma gangrenosum, erythema nodosum, erythema multiforme, epidermolysis bullosa acquisita, and palmar erythema.⁷ Metastatic CD involves skin noncontiguous with the gastrointestinal tract^1-20 and may involve any portion of the cutis. Although rare, MCD is the typical etiology underlying vulvar CD.⁸

Approximately 20% of MCD patients have cutaneous lesions without a history of gastrointestinal disease. More than half of cases in adults and approximately two-thirds in children involve the genitalia. Although more common in adults, vulvar involvement has been reported in children as young as 6 years of age.² Diagnosis is especially challenging when bowel symptoms are absent; those patients should be evaluated and followed for subsequent intestinal involvement.⁶

Clinically, symptoms may include general discomfort, pain, pruritus, and dyspareunia. Psychosocial and sexual dysfunction are prevalent and also should be addressed.⁹ Depending on the stage of the disease, physical examination may reveal erythema, edema, papules, pustules, nodules, condylomatous lesions, abscesses, fissures, fistulas, ulceration, acrochordons, and scarring.^2-6,10,11

A host of infections (ie, mycobacterial, actinomycosis, deep fungal, sexually transmitted, schistosomiasis), inflammatory conditions (ie, sarcoid, hidradenitis suppurativa), foreign body reactions, Melkersson-Rosenthal syndrome, and sexual abuse should be included in the differential diagnosis.^2,6,10-12 Once infection, sarcoid, and foreign body reaction have been ruled out, noncaseating granulomas in skin are highly suggestive of CD.⁷

Histopathologic findings of MCD reveal myriad morphological reaction patterns,^5,13 including high-grade dysplasia and carcinoma of the vulva; therefore, it may be imprudent to withhold diagnosis based on the absence of the historically pathognomonic noncaseating granulomas.⁵

The etiopathogenesis of MCD remains an enigma. Dermatopathologic examinations consistently reveal a vascular injury syndrome,¹³ implicating a possible circulatory system contribution via deposition of immune complexes or antigens in skin.⁷ Bacterial infection has been implicated in the intestinal manifestations of CD; however, failure to detect microbial ribosomal RNA in MCD biopsies refutes theories of hematogenous spread of microbes.¹³ Another plausible explanation is that antibodies are formed to conserved microbial epitopes following loss of tolerance to gut flora, which results in an excessive immunologic response at distinct sites in susceptible individuals.¹³ A T-lymphocyte–mediated type IV hypersensitivity reaction also has been proposed via cross-reactivity of lymphocytes, with skin antigens precipitating extraintestinal granuloma formation and vascular injury.³ Clearly, further investigation is needed.

Magnetic resonanance imaging can identify the extent and anatomy of intestinal and pelvic disease and can assist in the diagnosis of vulvar CD.^10,11,14 For these reasons, some experts propose that imaging should be instituted prior to therapy,^12,15,16 especially when direct extension is suspected.¹⁷

Treatment is challenging and often involves collaboration among several specialties.¹² Many treatment options exist because therapeutic responses vary and genital MCD is frequently recalcitrant to therapy.⁴ Medical therapy includes antibiotics such as metronidazole, corticosteroids (ie, topical, intralesional, systemic), and immune modulators (eg, azathioprine, 6-mercaptopurine, cyclosporine, methotrexate, mycophenolate mofetil, tumor necrosis factor α inhibitors).^{2,3,6,10,16,18} Thalidomide has been used for refractory cases.¹⁹ These treatments can be used alone or in combination. Patients should be monitored for side effects and informed that many treatment regimens may be required before a sustained response is achieved.^4,16,18 Surgery is reserved for the most resistant cases. Extensive radical excision of the involved area is the best approach, as limited local excision often is followed by recurrence.²⁰

Conclusion

Our case highlights that vulvar CD can develop in the setting of well-controlled intestinal disease. Vulvoperineal CD should be considered in the differential diagnosis of chronic vulvar pain, swelling, and pruritus, especially in cases resistant to standard therapies and regardless of whether or not gastrointestinal tract symptoms are present. Physicians must be cognizant that vulvar signs and symptoms may precede, coincide with, or follow the diagnosis of intestinal CD. Increased awareness of this entity may facilitate its early recognition and prompt more timely treatment among women with vulvar disease caused by MCD.

The cutaneous manifestations of Crohn disease (CD) are varied, including pyoderma gangrenosum, erythema nodosum, and metastatic CD (MCD). First described by Parks et al,¹ MCD is defined as the occurrence of granulomatous lesions at a skin site distant from the gastrointestinal tract.^1-20 Metastatic CD presents a diagnostic challenge because it is a rare component in the spectrum of inflammatory bowel disease complications, and many physicians are unaware of its existence. It may precede, coincide with, or develop after the diagnosis of intestinal disease.^2-5 Vulvoperineal involvement is particularly problematic because a multitude of other, more likely disease processes are considered first. Typically it is initially diagnosed as a presumed infection prompting reflexive treatment with antivirals, antifungals, and antibiotics. Patients may experience symptoms for years prior to correct diagnosis and institution of proper therapy. A variety of clinical presentations have been described, including nonspecific pain and swelling, erythematous papules and plaques, and nonhealing ulcers. Skin biopsy characteristically confirms the diagnosis and reveals dermal noncaseating granulomas. Multiple oral and parenteral therapies are available, with surgical intervention reserved for resistant cases. We present a case of vulvovaginal MCD in the setting of well-controlled intestinal disease. We also provide a review of the literature regarding genital CD and emphasize the need to keep MCD in the differential of vulvoperineal pathology.

Case Report

A 29-year-old woman was referred to the dermatology clinic with vulvar pain, swelling, and pruritus of 14 months’ duration. Her medical history was remarkable for CD following a colectomy with colostomy. Prior therapies included methotrexate with infliximab for 5 years followed by a 2-year regimen with adalimumab, which induced remission of the intestinal disease.

The patient previously had taken a variety of topical and oral antimicrobials based on treatment from a primary care physician because fungal, bacterial, and viral infections initially were suspected; however, the vulvar disease persisted, and drug-induced immunosuppression was considered to be an underlying factor. Thus, adalimumab was discontinued. Despite elimination of the biologic, the vulvar disease progressed, which prompted referral to the dermatology clinic.

Physical examination revealed diffuse vulvar edema with overlying erythema and scale (Figure 1A). Upon closer inspection, scattered violaceous papules atop a backdrop of lichenification were evident, imparting a cobblestone appearance (Figure 1B). Additionally, a fissure was present on the gluteal cleft. Biopsy from the left labia majora demonstrated well-formed granulomas within a fibrotic reticular dermis (Figures 2A and 2B). The granulomas consisted of both mononucleated and multinucleated histiocytes, rimmed peripherally by lymphocytes and plasma cells (Figure 2C). Periodic acid–Schiff–diastase and acid-fast bacilli stains as well as polarizing microscopy were negative.

Comment

Crohn disease is an idiopathic chronic inflammatory condition that primarily affects the gastrointestinal tract, anywhere from the mouth to the anus. It is characterized by transmural inflammation and fissures that can extend beyond the muscularis propria.^4,6 Extraintestinal manifestations are common.³

Cutaneous CD often presents as perianal, perifistular, or peristomal inflammation or ulceration.⁷ Other skin manifestations include pyoderma gangrenosum, erythema nodosum, erythema multiforme, epidermolysis bullosa acquisita, and palmar erythema.⁷ Metastatic CD involves skin noncontiguous with the gastrointestinal tract^1-20 and may involve any portion of the cutis. Although rare, MCD is the typical etiology underlying vulvar CD.⁸

Approximately 20% of MCD patients have cutaneous lesions without a history of gastrointestinal disease. More than half of cases in adults and approximately two-thirds in children involve the genitalia. Although more common in adults, vulvar involvement has been reported in children as young as 6 years of age.² Diagnosis is especially challenging when bowel symptoms are absent; those patients should be evaluated and followed for subsequent intestinal involvement.⁶

Clinically, symptoms may include general discomfort, pain, pruritus, and dyspareunia. Psychosocial and sexual dysfunction are prevalent and also should be addressed.⁹ Depending on the stage of the disease, physical examination may reveal erythema, edema, papules, pustules, nodules, condylomatous lesions, abscesses, fissures, fistulas, ulceration, acrochordons, and scarring.^2-6,10,11

A host of infections (ie, mycobacterial, actinomycosis, deep fungal, sexually transmitted, schistosomiasis), inflammatory conditions (ie, sarcoid, hidradenitis suppurativa), foreign body reactions, Melkersson-Rosenthal syndrome, and sexual abuse should be included in the differential diagnosis.^2,6,10-12 Once infection, sarcoid, and foreign body reaction have been ruled out, noncaseating granulomas in skin are highly suggestive of CD.⁷

Histopathologic findings of MCD reveal myriad morphological reaction patterns,^5,13 including high-grade dysplasia and carcinoma of the vulva; therefore, it may be imprudent to withhold diagnosis based on the absence of the historically pathognomonic noncaseating granulomas.⁵

The etiopathogenesis of MCD remains an enigma. Dermatopathologic examinations consistently reveal a vascular injury syndrome,¹³ implicating a possible circulatory system contribution via deposition of immune complexes or antigens in skin.⁷ Bacterial infection has been implicated in the intestinal manifestations of CD; however, failure to detect microbial ribosomal RNA in MCD biopsies refutes theories of hematogenous spread of microbes.¹³ Another plausible explanation is that antibodies are formed to conserved microbial epitopes following loss of tolerance to gut flora, which results in an excessive immunologic response at distinct sites in susceptible individuals.¹³ A T-lymphocyte–mediated type IV hypersensitivity reaction also has been proposed via cross-reactivity of lymphocytes, with skin antigens precipitating extraintestinal granuloma formation and vascular injury.³ Clearly, further investigation is needed.

Magnetic resonanance imaging can identify the extent and anatomy of intestinal and pelvic disease and can assist in the diagnosis of vulvar CD.^10,11,14 For these reasons, some experts propose that imaging should be instituted prior to therapy,^12,15,16 especially when direct extension is suspected.¹⁷

Treatment is challenging and often involves collaboration among several specialties.¹² Many treatment options exist because therapeutic responses vary and genital MCD is frequently recalcitrant to therapy.⁴ Medical therapy includes antibiotics such as metronidazole, corticosteroids (ie, topical, intralesional, systemic), and immune modulators (eg, azathioprine, 6-mercaptopurine, cyclosporine, methotrexate, mycophenolate mofetil, tumor necrosis factor α inhibitors).^{2,3,6,10,16,18} Thalidomide has been used for refractory cases.¹⁹ These treatments can be used alone or in combination. Patients should be monitored for side effects and informed that many treatment regimens may be required before a sustained response is achieved.^4,16,18 Surgery is reserved for the most resistant cases. Extensive radical excision of the involved area is the best approach, as limited local excision often is followed by recurrence.²⁰

Conclusion

Our case highlights that vulvar CD can develop in the setting of well-controlled intestinal disease. Vulvoperineal CD should be considered in the differential diagnosis of chronic vulvar pain, swelling, and pruritus, especially in cases resistant to standard therapies and regardless of whether or not gastrointestinal tract symptoms are present. Physicians must be cognizant that vulvar signs and symptoms may precede, coincide with, or follow the diagnosis of intestinal CD. Increased awareness of this entity may facilitate its early recognition and prompt more timely treatment among women with vulvar disease caused by MCD.

To the Editor:

Microcystic adnexal carcinoma (MAC), described by Goldstein et al¹ in 1982, is a relatively uncommon cutaneous neoplasm. This locally aggressive malignant adnexal tumor has high potential for local recurrence. The skin of the head, particularly in the nasolabial and periorbital regions, most often is involved.² Involvement of the external auditory canal (EAC) is relatively rare. We report a case of MAC of the EAC.

A 52-year-old man presented with 1 palpable nodule on the right EAC of approximately 1 year’s duration. The lesion was asymptomatic, and the patient had no history of radiation exposure. The patient was an airport employee required to wear an earplug in the right ear. Endoscopic examination identified a 1×1 cm² erythematous nodule on the anterior inferior quadrant of the right external ear canal orifice (Figure 1). Axial and coronal computed tomography demonstrated a soft tissue mass in the right EAC without any bony erosion. No clinical signs of regional lymphadenopathy or distant metastasis were present. Excision was performed under microscopic visualization.

Histopathology of the nodule showed marked proliferation of multiple keratin-containing cysts, irregular ductal structures, and solid epithelial nests in the deep dermis (Figure 2). Irregular ductal structures with 2 cell layer walls and several epithelial strands or small nests of tumor cells within desmoplastic stroma were noted (Figure 3). No perineural infiltration or tumor infiltration existed at the margin. Based on the clinical and histopathologic findings, the final diagnosis was MAC. Complete resolution was noted after the excision. The patient returned for regular follow-up and no signs of recurrence were noted for 7 years postoperatively.

Microcystic adnexal carcinoma, also known as sclerosing sweat duct (syringomatous) carcinoma, malignant syringoma, and syringoid eccrine carcinoma, is characterized by slow and locally aggressive growth with high likelihood of perineural invasion and frequent recurrence.² Regional lymph node metastasis is uncommon, and systemic metastasis is rare.^2-4

Although the head most often is involved, a PubMed search of articles indexed for MEDLINE using the terms microcystic adnexal carcinoma and external auditory canal revealed 4 cases (Table).^5-8 Our report adds another case of MAC arising solely in the EAC. Although the etiology of MAC is unknown, prior studies indicated that radiotherapy is a risk factor for MAC. Other possible risk factors include UV light exposure and immunodeficiency.² Our patient had no history of these factors and experienced chronic friction caused by use of an occupational unilateral earplug, which may be a notable factor. Locations of MAC arising outside the head region include the axilla, vulva, breast, palm, toe, perianal skin, buttock, chest, and an ovarian cystic teratoma.^3,9 Friction commonly occurs in many of these areas. Therefore, we propose that friction may be a risk factor for MAC.

Microcystic adnexal carcinoma should be included in the differential diagnosis of any slowly growing cutaneous tumor, even in the EAC. Once diagnosed, the tumor should be surgically excised. Because local recurrence is common and may occur several decades after excision, lifetime follow-up for recurrence signs is essential.

To the Editor:

Microcystic adnexal carcinoma (MAC), described by Goldstein et al¹ in 1982, is a relatively uncommon cutaneous neoplasm. This locally aggressive malignant adnexal tumor has high potential for local recurrence. The skin of the head, particularly in the nasolabial and periorbital regions, most often is involved.² Involvement of the external auditory canal (EAC) is relatively rare. We report a case of MAC of the EAC.

A 52-year-old man presented with 1 palpable nodule on the right EAC of approximately 1 year’s duration. The lesion was asymptomatic, and the patient had no history of radiation exposure. The patient was an airport employee required to wear an earplug in the right ear. Endoscopic examination identified a 1×1 cm² erythematous nodule on the anterior inferior quadrant of the right external ear canal orifice (Figure 1). Axial and coronal computed tomography demonstrated a soft tissue mass in the right EAC without any bony erosion. No clinical signs of regional lymphadenopathy or distant metastasis were present. Excision was performed under microscopic visualization.

Histopathology of the nodule showed marked proliferation of multiple keratin-containing cysts, irregular ductal structures, and solid epithelial nests in the deep dermis (Figure 2). Irregular ductal structures with 2 cell layer walls and several epithelial strands or small nests of tumor cells within desmoplastic stroma were noted (Figure 3). No perineural infiltration or tumor infiltration existed at the margin. Based on the clinical and histopathologic findings, the final diagnosis was MAC. Complete resolution was noted after the excision. The patient returned for regular follow-up and no signs of recurrence were noted for 7 years postoperatively.

Microcystic adnexal carcinoma, also known as sclerosing sweat duct (syringomatous) carcinoma, malignant syringoma, and syringoid eccrine carcinoma, is characterized by slow and locally aggressive growth with high likelihood of perineural invasion and frequent recurrence.² Regional lymph node metastasis is uncommon, and systemic metastasis is rare.^2-4

Although the head most often is involved, a PubMed search of articles indexed for MEDLINE using the terms microcystic adnexal carcinoma and external auditory canal revealed 4 cases (Table).^5-8 Our report adds another case of MAC arising solely in the EAC. Although the etiology of MAC is unknown, prior studies indicated that radiotherapy is a risk factor for MAC. Other possible risk factors include UV light exposure and immunodeficiency.² Our patient had no history of these factors and experienced chronic friction caused by use of an occupational unilateral earplug, which may be a notable factor. Locations of MAC arising outside the head region include the axilla, vulva, breast, palm, toe, perianal skin, buttock, chest, and an ovarian cystic teratoma.^3,9 Friction commonly occurs in many of these areas. Therefore, we propose that friction may be a risk factor for MAC.

Microcystic adnexal carcinoma should be included in the differential diagnosis of any slowly growing cutaneous tumor, even in the EAC. Once diagnosed, the tumor should be surgically excised. Because local recurrence is common and may occur several decades after excision, lifetime follow-up for recurrence signs is essential.

To the Editor:

Microcystic adnexal carcinoma (MAC), described by Goldstein et al¹ in 1982, is a relatively uncommon cutaneous neoplasm. This locally aggressive malignant adnexal tumor has high potential for local recurrence. The skin of the head, particularly in the nasolabial and periorbital regions, most often is involved.² Involvement of the external auditory canal (EAC) is relatively rare. We report a case of MAC of the EAC.

A 52-year-old man presented with 1 palpable nodule on the right EAC of approximately 1 year’s duration. The lesion was asymptomatic, and the patient had no history of radiation exposure. The patient was an airport employee required to wear an earplug in the right ear. Endoscopic examination identified a 1×1 cm² erythematous nodule on the anterior inferior quadrant of the right external ear canal orifice (Figure 1). Axial and coronal computed tomography demonstrated a soft tissue mass in the right EAC without any bony erosion. No clinical signs of regional lymphadenopathy or distant metastasis were present. Excision was performed under microscopic visualization.

Histopathology of the nodule showed marked proliferation of multiple keratin-containing cysts, irregular ductal structures, and solid epithelial nests in the deep dermis (Figure 2). Irregular ductal structures with 2 cell layer walls and several epithelial strands or small nests of tumor cells within desmoplastic stroma were noted (Figure 3). No perineural infiltration or tumor infiltration existed at the margin. Based on the clinical and histopathologic findings, the final diagnosis was MAC. Complete resolution was noted after the excision. The patient returned for regular follow-up and no signs of recurrence were noted for 7 years postoperatively.

Microcystic adnexal carcinoma, also known as sclerosing sweat duct (syringomatous) carcinoma, malignant syringoma, and syringoid eccrine carcinoma, is characterized by slow and locally aggressive growth with high likelihood of perineural invasion and frequent recurrence.² Regional lymph node metastasis is uncommon, and systemic metastasis is rare.^2-4

Although the head most often is involved, a PubMed search of articles indexed for MEDLINE using the terms microcystic adnexal carcinoma and external auditory canal revealed 4 cases (Table).^5-8 Our report adds another case of MAC arising solely in the EAC. Although the etiology of MAC is unknown, prior studies indicated that radiotherapy is a risk factor for MAC. Other possible risk factors include UV light exposure and immunodeficiency.² Our patient had no history of these factors and experienced chronic friction caused by use of an occupational unilateral earplug, which may be a notable factor. Locations of MAC arising outside the head region include the axilla, vulva, breast, palm, toe, perianal skin, buttock, chest, and an ovarian cystic teratoma.^3,9 Friction commonly occurs in many of these areas. Therefore, we propose that friction may be a risk factor for MAC.

Microcystic adnexal carcinoma should be included in the differential diagnosis of any slowly growing cutaneous tumor, even in the EAC. Once diagnosed, the tumor should be surgically excised. Because local recurrence is common and may occur several decades after excision, lifetime follow-up for recurrence signs is essential.

Inflammatory linear verrucous epidermal nevus (ILVEN) is a rare entity that presents with linear and pruritic psoriasiform plaques and most commonly occurs during childhood. It represents a dysregulation of keratinocytes exhibiting genetic mosaicism.^1,2 Epidermal nevi may derive from keratinocytic, follicular, sebaceous, apocrine, or eccrine origin. Inflammatory linear verrucous epidermal nevus is classified under the keratinocytic type of epidermal nevus and represents approximately 6% of all epidermal nevi.³ The condition presents as erythematous and verrucous plaques along the lines of Blaschko.^2,4 There is a predilection for the legs, and girls are 4 times more commonly affected than boys.¹ Cases of ILVEN are predominantly sporadic, though rare familial cases have been reported.⁴

Inflammatory linear verrucous epidermal nevus is notoriously refractory to treatment. First-line therapies include topical agents such as corticosteroids, calcipotriol, retinoids, and 5-fluorouracil.^3,4 Other treatments include intralesional corticosteroids, cryotherapy, electrodesiccation and curettage, and surgical excision.³ Several case reports have shown promising results using the pulsed dye and ablative CO2 lasers.^5-8

Case Report

An otherwise healthy 20-year-old woman presented with dry, pruritic, red lesions on the right leg that had been present and stable since she was an infant (2 weeks of age). Her medical history included acne vulgaris, but she denied any personal or family history of psoriasis as well as any arthralgia or arthritis. Physical examination revealed discrete, oval, hyperkeratotic, scaly, red plaques on the lateral right leg with a larger hyperkeratotic, linear, red plaque extending from the right popliteal fossa to the posterior thigh (Figure 1A). The nails, scalp, buttocks, and upper extremities were unaffected. Bacterial culture of the right leg demonstrated Staphylococcus aureus colonization. Biopsy of the right popliteal fossa showed psoriasiform dermatitis with psoriasiform hyperplasia, a slightly verruciform surface, broad zones of superficial pallor, and parakeratosis with conspicuous colonies of bacteria (Figure 2).

Following the positive bacterial culture, the patient was treated with a short course of oral doxycycline, which did not alter the clinical appearance of the lesions or improve symptoms of pruritus. Pruritus improved moderately with topical corticosteroid treatment, but clinically the lesions appeared unchanged. The plaque on the superior right leg was treated with a superpulsed CO₂ laser and the plaque on the inferior right leg was treated with a fractional CO₂ laser, both with minimal improvement.

Because of the clinical and histopathologic similarities of the patient's lesions to psoriasis, a trial of the UV 308-nm excimer laser was initiated. Following initial test spots, she completed a total of 18 treatments to all lesions with noticeable clinical improvement (Figure 1B). Initially, the patient returned for treatment biweekly for approximately 5 weeks with 2 small spots being targeted at each session, with an average surface area of approximately 16 cm². She was started at 225 mJ/cm² with 25% increases at each session and ultimately reached up to 1676 mJ/cm² at the end of the 10 sessions. She tolerated the procedure well with some minor blistering. Treatment was deferred for 3 months due to the patient's schedule, then biweekly treatments resumed for 4 weeks, totaling 8 more sessions. At that time, all lesions on the right leg were targeted, with an average surface area of approximately 100 cm². The laser settings were initiated at 225 mJ/cm² with 20% increases at each session and ultimately reached 560 mJ/cm². The treatment was well tolerated throughout; however, the patient initially reported residual pruritus. The plaques continued to improve, and most notably, there was thinning of the hyperkeratotic scale of the plaques in addition to decreased erythema and complete resolution of pruritus. Ultimately, treatment was discontinued because of lack of insurance coverage and financial burden. The patient was lost to follow-up.

Comment

Presentation
Inflammatory linear verrucous epidermal nevus is a rare type of keratinocytic epidermal nevus⁴ that clinically presents as small, discrete, pruritic, scaly plaques coalescing into a linear plaque along the lines of Blaschko.⁹ Considerable pruritus and resistance to treatment are hallmarks of the disease.¹⁰ Histopathologically, ILVEN is characterized by alternating orthokeratosis and parakeratosis with a lack of neutrophils in an acanthotic epidermis.^11-13 Inflammatory linear verrucous epidermal nevus presents at birth or in early childhood. Adult onset is rare.^9,14 Approximately 75% of lesions present by 5 years of age, with a majority occurring within the first 6 months of life.¹⁵ The differential diagnosis includes linear psoriasis, epidermal nevi, linear lichen planus, linear verrucae, linear lichen simplex chronicus, and mycosis fungoides.^4,11

Differentiation From Psoriasis
Despite the histopathologic overlap with psoriasis, ILVEN exhibits fewer Ki-67-positive keratinocyte nuclei (proliferative marker) and more cytokeratin 10-positive cells (epidermal differentiation marker) than psoriasis.¹⁶ Furthermore, ILVEN has demonstrated fewer CD4⁻, CD8⁻, CD45RO⁻, CD2⁻, CD25⁻, CD94⁻, and CD161⁺ cells within the dermis and epidermis than psoriasis.¹⁶

The clinical presentations of ILVEN and psoriasis may be similar, as some patients with linear psoriasis also present with psoriatic plaques along the lines of Blaschko.¹⁷ Additionally, ILVEN may be a precursor to psoriasis. Altman and Mehregan1 found that ILVEN patients who developed psoriasis did so in areas previously affected by ILVEN; however, they continued to distinguish the 2 pathologies as distinct entities. Another early report also hypothesized that the dermoepidermal defect caused by epidermal nevi provided a site for the development of psoriatic lesions because of the Koebner phenomenon.¹⁸

Patients with ILVEN also have been found to have extracutaneous manifestations and symptoms commonly seen in psoriasis patients. A 2012 retrospective review revealed that 37% (7/19) of patients with ILVEN also had psoriatic arthritis, cutaneous psoriatic lesions, and/or nail pitting. The authors concluded that ILVEN may lead to the onset of psoriasis later in life and may indicate an underlying psoriatic predisposition.¹⁹ Genetic theories also have been proposed, stating that ILVEN may be a mosaic of psoriasis2 or that a postzygotic mutation leads to the predisposition for developing psoriasis.²⁰

Treatment
Inflammatory linear verrucous epidermal nevus frequently is refractory to treatment; however, the associated pruritus and distressing cosmesis make treatment attempts worthwhile.¹¹ No single therapy has been found to be successful in all patients. A widely used first-line treatment is topical or intralesional corticosteroids, with the former typically used with occlusion.¹³ Other treatments include adalimumab, calcipotriol,^22,23 tretinoin,²⁴ and 5-fluorouracil.²⁴ Physical modalities such as cryotherapy, electrodesiccation, and dermabrasion have been reported with varying success.^15,24 Surgical treatments include tangential²⁵ and full-thickness excisions.²⁶

The CO₂ laser also has demonstrated success. One study showed considerable improvement of pruritus and partial resolution of lesions only 5 weeks following a single CO₂ laser treatment.⁵ Another study showed promising results when combining CO₂ pulsed laser therapy with fractional CO₂ laser treatment.⁶ Other laser therapies including the argon²⁷ and flashlamp-pumped pulsed dye lasers⁸ have been used with limited success. The use of light therapy and lasers in psoriasis have now increased the treatment options for ILVEN based on the rationale of their shared histopathologic characteristics. Photodynamic therapy also has been attempted because of its successful use in psoriasis patients. It has been found to be successful in diminishing ILVEN lesions and associated pruritus after a few weeks of therapy; however, treatment is limited by the associated pain and requirement for local anesthesia.²⁸

The excimer laser is a form of targeted phototherapy that emits monochromatic light at 308 nm.²⁹ It is ideal for inflammatory skin lesions because the UVB light induces apoptosis.³⁰ Psoriasis lesions treated with the excimer laser show a decrease in keratinocyte proliferation, which in turn reverses epidermal acanthosis and causes T-cell depletion due to upregulation of p53.^29,31 This mechanism of action addresses the overproliferation of keratinocytes mediated by T cells in psoriasis and contributes to the success of excimer laser treatment.³¹ A considerable advantage is its localized treatment, resulting in lower cumulative doses of UVB and reducing the possible carcinogenic and phototoxic risks of whole-body phototherapy.³²

One study examined the antipruritic effects of the excimer laser following the treatment of epidermal hyperinnervation leading to intractable pruritus in patients with atopic dermatitis. The researchers suggested that a potential explanation for the antipruritic effect of the excimer laser may be secondary to nerve degeneration.³³ Additionally, low doses of UVB light also may inhibit mast cell degranulation and prevent histamine release, further supporting the antipruritic properties of excimer laser.³⁴

In our patient, failed treatment with other modalities led to trial of excimer laser therapy because of the overlapping clinical and histopathologic findings with psoriasis. Excimer laser improved the clinical appearance and overall texture of the ILVEN lesions and decreased pruritus. The reasons for treatment success may be two-fold. By decreasing the number of keratinocytes and mast cells, the excimer laser may have improved the epidermal hyperplasia and pruritus in the ILVEN lesions. Alternatively, because the patient had ILVEN lesions since infancy, psoriasis may have developed in the location of the ILVEN lesions due to koebnerization, resulting in the clinical response to excimer therapy; however, she had no other clinical evidence of psoriasis.

Because of the recalcitrance of ILVEN lesions to conventional therapies, it is important to investigate therapies that may be of possible benefit. Our novel case documents successful use of the excimer laser in the treatment of ILVEN. 

Conclusion

Our case of ILVEN in a woman that had been present since infancy highlights the disease pathology as well as a potential new treatment modality. The patient was refractory to first-line treatments and was concerned about the cosmetic appearance of the lesions. The patient was subsequently treated with a trial of a 308-nm excimer laser with clinical improvement of the lesions. It is possible that the similarity of ILVEN and psoriasis may have contributed to the clinical improvement in our patient, but the mechanism of action remains unknown. Due to the paucity of evidence regarding optimal treatment of ILVEN, the current case offers dermatologists an option for patients who are refractory to other treatments.
 

Inflammatory linear verrucous epidermal nevus (ILVEN) is a rare entity that presents with linear and pruritic psoriasiform plaques and most commonly occurs during childhood. It represents a dysregulation of keratinocytes exhibiting genetic mosaicism.^1,2 Epidermal nevi may derive from keratinocytic, follicular, sebaceous, apocrine, or eccrine origin. Inflammatory linear verrucous epidermal nevus is classified under the keratinocytic type of epidermal nevus and represents approximately 6% of all epidermal nevi.³ The condition presents as erythematous and verrucous plaques along the lines of Blaschko.^2,4 There is a predilection for the legs, and girls are 4 times more commonly affected than boys.¹ Cases of ILVEN are predominantly sporadic, though rare familial cases have been reported.⁴

Inflammatory linear verrucous epidermal nevus is notoriously refractory to treatment. First-line therapies include topical agents such as corticosteroids, calcipotriol, retinoids, and 5-fluorouracil.^3,4 Other treatments include intralesional corticosteroids, cryotherapy, electrodesiccation and curettage, and surgical excision.³ Several case reports have shown promising results using the pulsed dye and ablative CO2 lasers.^5-8

Case Report

An otherwise healthy 20-year-old woman presented with dry, pruritic, red lesions on the right leg that had been present and stable since she was an infant (2 weeks of age). Her medical history included acne vulgaris, but she denied any personal or family history of psoriasis as well as any arthralgia or arthritis. Physical examination revealed discrete, oval, hyperkeratotic, scaly, red plaques on the lateral right leg with a larger hyperkeratotic, linear, red plaque extending from the right popliteal fossa to the posterior thigh (Figure 1A). The nails, scalp, buttocks, and upper extremities were unaffected. Bacterial culture of the right leg demonstrated Staphylococcus aureus colonization. Biopsy of the right popliteal fossa showed psoriasiform dermatitis with psoriasiform hyperplasia, a slightly verruciform surface, broad zones of superficial pallor, and parakeratosis with conspicuous colonies of bacteria (Figure 2).

Following the positive bacterial culture, the patient was treated with a short course of oral doxycycline, which did not alter the clinical appearance of the lesions or improve symptoms of pruritus. Pruritus improved moderately with topical corticosteroid treatment, but clinically the lesions appeared unchanged. The plaque on the superior right leg was treated with a superpulsed CO₂ laser and the plaque on the inferior right leg was treated with a fractional CO₂ laser, both with minimal improvement.

Because of the clinical and histopathologic similarities of the patient's lesions to psoriasis, a trial of the UV 308-nm excimer laser was initiated. Following initial test spots, she completed a total of 18 treatments to all lesions with noticeable clinical improvement (Figure 1B). Initially, the patient returned for treatment biweekly for approximately 5 weeks with 2 small spots being targeted at each session, with an average surface area of approximately 16 cm². She was started at 225 mJ/cm² with 25% increases at each session and ultimately reached up to 1676 mJ/cm² at the end of the 10 sessions. She tolerated the procedure well with some minor blistering. Treatment was deferred for 3 months due to the patient's schedule, then biweekly treatments resumed for 4 weeks, totaling 8 more sessions. At that time, all lesions on the right leg were targeted, with an average surface area of approximately 100 cm². The laser settings were initiated at 225 mJ/cm² with 20% increases at each session and ultimately reached 560 mJ/cm². The treatment was well tolerated throughout; however, the patient initially reported residual pruritus. The plaques continued to improve, and most notably, there was thinning of the hyperkeratotic scale of the plaques in addition to decreased erythema and complete resolution of pruritus. Ultimately, treatment was discontinued because of lack of insurance coverage and financial burden. The patient was lost to follow-up.

Comment

Presentation
Inflammatory linear verrucous epidermal nevus is a rare type of keratinocytic epidermal nevus⁴ that clinically presents as small, discrete, pruritic, scaly plaques coalescing into a linear plaque along the lines of Blaschko.⁹ Considerable pruritus and resistance to treatment are hallmarks of the disease.¹⁰ Histopathologically, ILVEN is characterized by alternating orthokeratosis and parakeratosis with a lack of neutrophils in an acanthotic epidermis.^11-13 Inflammatory linear verrucous epidermal nevus presents at birth or in early childhood. Adult onset is rare.^9,14 Approximately 75% of lesions present by 5 years of age, with a majority occurring within the first 6 months of life.¹⁵ The differential diagnosis includes linear psoriasis, epidermal nevi, linear lichen planus, linear verrucae, linear lichen simplex chronicus, and mycosis fungoides.^4,11

Differentiation From Psoriasis
Despite the histopathologic overlap with psoriasis, ILVEN exhibits fewer Ki-67-positive keratinocyte nuclei (proliferative marker) and more cytokeratin 10-positive cells (epidermal differentiation marker) than psoriasis.¹⁶ Furthermore, ILVEN has demonstrated fewer CD4⁻, CD8⁻, CD45RO⁻, CD2⁻, CD25⁻, CD94⁻, and CD161⁺ cells within the dermis and epidermis than psoriasis.¹⁶

The clinical presentations of ILVEN and psoriasis may be similar, as some patients with linear psoriasis also present with psoriatic plaques along the lines of Blaschko.¹⁷ Additionally, ILVEN may be a precursor to psoriasis. Altman and Mehregan1 found that ILVEN patients who developed psoriasis did so in areas previously affected by ILVEN; however, they continued to distinguish the 2 pathologies as distinct entities. Another early report also hypothesized that the dermoepidermal defect caused by epidermal nevi provided a site for the development of psoriatic lesions because of the Koebner phenomenon.¹⁸

Patients with ILVEN also have been found to have extracutaneous manifestations and symptoms commonly seen in psoriasis patients. A 2012 retrospective review revealed that 37% (7/19) of patients with ILVEN also had psoriatic arthritis, cutaneous psoriatic lesions, and/or nail pitting. The authors concluded that ILVEN may lead to the onset of psoriasis later in life and may indicate an underlying psoriatic predisposition.¹⁹ Genetic theories also have been proposed, stating that ILVEN may be a mosaic of psoriasis2 or that a postzygotic mutation leads to the predisposition for developing psoriasis.²⁰

Treatment
Inflammatory linear verrucous epidermal nevus frequently is refractory to treatment; however, the associated pruritus and distressing cosmesis make treatment attempts worthwhile.¹¹ No single therapy has been found to be successful in all patients. A widely used first-line treatment is topical or intralesional corticosteroids, with the former typically used with occlusion.¹³ Other treatments include adalimumab, calcipotriol,^22,23 tretinoin,²⁴ and 5-fluorouracil.²⁴ Physical modalities such as cryotherapy, electrodesiccation, and dermabrasion have been reported with varying success.^15,24 Surgical treatments include tangential²⁵ and full-thickness excisions.²⁶

The CO₂ laser also has demonstrated success. One study showed considerable improvement of pruritus and partial resolution of lesions only 5 weeks following a single CO₂ laser treatment.⁵ Another study showed promising results when combining CO₂ pulsed laser therapy with fractional CO₂ laser treatment.⁶ Other laser therapies including the argon²⁷ and flashlamp-pumped pulsed dye lasers⁸ have been used with limited success. The use of light therapy and lasers in psoriasis have now increased the treatment options for ILVEN based on the rationale of their shared histopathologic characteristics. Photodynamic therapy also has been attempted because of its successful use in psoriasis patients. It has been found to be successful in diminishing ILVEN lesions and associated pruritus after a few weeks of therapy; however, treatment is limited by the associated pain and requirement for local anesthesia.²⁸

The excimer laser is a form of targeted phototherapy that emits monochromatic light at 308 nm.²⁹ It is ideal for inflammatory skin lesions because the UVB light induces apoptosis.³⁰ Psoriasis lesions treated with the excimer laser show a decrease in keratinocyte proliferation, which in turn reverses epidermal acanthosis and causes T-cell depletion due to upregulation of p53.^29,31 This mechanism of action addresses the overproliferation of keratinocytes mediated by T cells in psoriasis and contributes to the success of excimer laser treatment.³¹ A considerable advantage is its localized treatment, resulting in lower cumulative doses of UVB and reducing the possible carcinogenic and phototoxic risks of whole-body phototherapy.³²

One study examined the antipruritic effects of the excimer laser following the treatment of epidermal hyperinnervation leading to intractable pruritus in patients with atopic dermatitis. The researchers suggested that a potential explanation for the antipruritic effect of the excimer laser may be secondary to nerve degeneration.³³ Additionally, low doses of UVB light also may inhibit mast cell degranulation and prevent histamine release, further supporting the antipruritic properties of excimer laser.³⁴

In our patient, failed treatment with other modalities led to trial of excimer laser therapy because of the overlapping clinical and histopathologic findings with psoriasis. Excimer laser improved the clinical appearance and overall texture of the ILVEN lesions and decreased pruritus. The reasons for treatment success may be two-fold. By decreasing the number of keratinocytes and mast cells, the excimer laser may have improved the epidermal hyperplasia and pruritus in the ILVEN lesions. Alternatively, because the patient had ILVEN lesions since infancy, psoriasis may have developed in the location of the ILVEN lesions due to koebnerization, resulting in the clinical response to excimer therapy; however, she had no other clinical evidence of psoriasis.

Because of the recalcitrance of ILVEN lesions to conventional therapies, it is important to investigate therapies that may be of possible benefit. Our novel case documents successful use of the excimer laser in the treatment of ILVEN. 

Conclusion

Our case of ILVEN in a woman that had been present since infancy highlights the disease pathology as well as a potential new treatment modality. The patient was refractory to first-line treatments and was concerned about the cosmetic appearance of the lesions. The patient was subsequently treated with a trial of a 308-nm excimer laser with clinical improvement of the lesions. It is possible that the similarity of ILVEN and psoriasis may have contributed to the clinical improvement in our patient, but the mechanism of action remains unknown. Due to the paucity of evidence regarding optimal treatment of ILVEN, the current case offers dermatologists an option for patients who are refractory to other treatments.
 

Inflammatory linear verrucous epidermal nevus (ILVEN) is a rare entity that presents with linear and pruritic psoriasiform plaques and most commonly occurs during childhood. It represents a dysregulation of keratinocytes exhibiting genetic mosaicism.^1,2 Epidermal nevi may derive from keratinocytic, follicular, sebaceous, apocrine, or eccrine origin. Inflammatory linear verrucous epidermal nevus is classified under the keratinocytic type of epidermal nevus and represents approximately 6% of all epidermal nevi.³ The condition presents as erythematous and verrucous plaques along the lines of Blaschko.^2,4 There is a predilection for the legs, and girls are 4 times more commonly affected than boys.¹ Cases of ILVEN are predominantly sporadic, though rare familial cases have been reported.⁴

Inflammatory linear verrucous epidermal nevus is notoriously refractory to treatment. First-line therapies include topical agents such as corticosteroids, calcipotriol, retinoids, and 5-fluorouracil.^3,4 Other treatments include intralesional corticosteroids, cryotherapy, electrodesiccation and curettage, and surgical excision.³ Several case reports have shown promising results using the pulsed dye and ablative CO2 lasers.^5-8

Case Report

An otherwise healthy 20-year-old woman presented with dry, pruritic, red lesions on the right leg that had been present and stable since she was an infant (2 weeks of age). Her medical history included acne vulgaris, but she denied any personal or family history of psoriasis as well as any arthralgia or arthritis. Physical examination revealed discrete, oval, hyperkeratotic, scaly, red plaques on the lateral right leg with a larger hyperkeratotic, linear, red plaque extending from the right popliteal fossa to the posterior thigh (Figure 1A). The nails, scalp, buttocks, and upper extremities were unaffected. Bacterial culture of the right leg demonstrated Staphylococcus aureus colonization. Biopsy of the right popliteal fossa showed psoriasiform dermatitis with psoriasiform hyperplasia, a slightly verruciform surface, broad zones of superficial pallor, and parakeratosis with conspicuous colonies of bacteria (Figure 2).

Following the positive bacterial culture, the patient was treated with a short course of oral doxycycline, which did not alter the clinical appearance of the lesions or improve symptoms of pruritus. Pruritus improved moderately with topical corticosteroid treatment, but clinically the lesions appeared unchanged. The plaque on the superior right leg was treated with a superpulsed CO₂ laser and the plaque on the inferior right leg was treated with a fractional CO₂ laser, both with minimal improvement.

Because of the clinical and histopathologic similarities of the patient's lesions to psoriasis, a trial of the UV 308-nm excimer laser was initiated. Following initial test spots, she completed a total of 18 treatments to all lesions with noticeable clinical improvement (Figure 1B). Initially, the patient returned for treatment biweekly for approximately 5 weeks with 2 small spots being targeted at each session, with an average surface area of approximately 16 cm². She was started at 225 mJ/cm² with 25% increases at each session and ultimately reached up to 1676 mJ/cm² at the end of the 10 sessions. She tolerated the procedure well with some minor blistering. Treatment was deferred for 3 months due to the patient's schedule, then biweekly treatments resumed for 4 weeks, totaling 8 more sessions. At that time, all lesions on the right leg were targeted, with an average surface area of approximately 100 cm². The laser settings were initiated at 225 mJ/cm² with 20% increases at each session and ultimately reached 560 mJ/cm². The treatment was well tolerated throughout; however, the patient initially reported residual pruritus. The plaques continued to improve, and most notably, there was thinning of the hyperkeratotic scale of the plaques in addition to decreased erythema and complete resolution of pruritus. Ultimately, treatment was discontinued because of lack of insurance coverage and financial burden. The patient was lost to follow-up.

Comment

Presentation
Inflammatory linear verrucous epidermal nevus is a rare type of keratinocytic epidermal nevus⁴ that clinically presents as small, discrete, pruritic, scaly plaques coalescing into a linear plaque along the lines of Blaschko.⁹ Considerable pruritus and resistance to treatment are hallmarks of the disease.¹⁰ Histopathologically, ILVEN is characterized by alternating orthokeratosis and parakeratosis with a lack of neutrophils in an acanthotic epidermis.^11-13 Inflammatory linear verrucous epidermal nevus presents at birth or in early childhood. Adult onset is rare.^9,14 Approximately 75% of lesions present by 5 years of age, with a majority occurring within the first 6 months of life.¹⁵ The differential diagnosis includes linear psoriasis, epidermal nevi, linear lichen planus, linear verrucae, linear lichen simplex chronicus, and mycosis fungoides.^4,11

Differentiation From Psoriasis
Despite the histopathologic overlap with psoriasis, ILVEN exhibits fewer Ki-67-positive keratinocyte nuclei (proliferative marker) and more cytokeratin 10-positive cells (epidermal differentiation marker) than psoriasis.¹⁶ Furthermore, ILVEN has demonstrated fewer CD4⁻, CD8⁻, CD45RO⁻, CD2⁻, CD25⁻, CD94⁻, and CD161⁺ cells within the dermis and epidermis than psoriasis.¹⁶

The clinical presentations of ILVEN and psoriasis may be similar, as some patients with linear psoriasis also present with psoriatic plaques along the lines of Blaschko.¹⁷ Additionally, ILVEN may be a precursor to psoriasis. Altman and Mehregan1 found that ILVEN patients who developed psoriasis did so in areas previously affected by ILVEN; however, they continued to distinguish the 2 pathologies as distinct entities. Another early report also hypothesized that the dermoepidermal defect caused by epidermal nevi provided a site for the development of psoriatic lesions because of the Koebner phenomenon.¹⁸

Patients with ILVEN also have been found to have extracutaneous manifestations and symptoms commonly seen in psoriasis patients. A 2012 retrospective review revealed that 37% (7/19) of patients with ILVEN also had psoriatic arthritis, cutaneous psoriatic lesions, and/or nail pitting. The authors concluded that ILVEN may lead to the onset of psoriasis later in life and may indicate an underlying psoriatic predisposition.¹⁹ Genetic theories also have been proposed, stating that ILVEN may be a mosaic of psoriasis2 or that a postzygotic mutation leads to the predisposition for developing psoriasis.²⁰

Treatment
Inflammatory linear verrucous epidermal nevus frequently is refractory to treatment; however, the associated pruritus and distressing cosmesis make treatment attempts worthwhile.¹¹ No single therapy has been found to be successful in all patients. A widely used first-line treatment is topical or intralesional corticosteroids, with the former typically used with occlusion.¹³ Other treatments include adalimumab, calcipotriol,^22,23 tretinoin,²⁴ and 5-fluorouracil.²⁴ Physical modalities such as cryotherapy, electrodesiccation, and dermabrasion have been reported with varying success.^15,24 Surgical treatments include tangential²⁵ and full-thickness excisions.²⁶

The CO₂ laser also has demonstrated success. One study showed considerable improvement of pruritus and partial resolution of lesions only 5 weeks following a single CO₂ laser treatment.⁵ Another study showed promising results when combining CO₂ pulsed laser therapy with fractional CO₂ laser treatment.⁶ Other laser therapies including the argon²⁷ and flashlamp-pumped pulsed dye lasers⁸ have been used with limited success. The use of light therapy and lasers in psoriasis have now increased the treatment options for ILVEN based on the rationale of their shared histopathologic characteristics. Photodynamic therapy also has been attempted because of its successful use in psoriasis patients. It has been found to be successful in diminishing ILVEN lesions and associated pruritus after a few weeks of therapy; however, treatment is limited by the associated pain and requirement for local anesthesia.²⁸

The excimer laser is a form of targeted phototherapy that emits monochromatic light at 308 nm.²⁹ It is ideal for inflammatory skin lesions because the UVB light induces apoptosis.³⁰ Psoriasis lesions treated with the excimer laser show a decrease in keratinocyte proliferation, which in turn reverses epidermal acanthosis and causes T-cell depletion due to upregulation of p53.^29,31 This mechanism of action addresses the overproliferation of keratinocytes mediated by T cells in psoriasis and contributes to the success of excimer laser treatment.³¹ A considerable advantage is its localized treatment, resulting in lower cumulative doses of UVB and reducing the possible carcinogenic and phototoxic risks of whole-body phototherapy.³²

One study examined the antipruritic effects of the excimer laser following the treatment of epidermal hyperinnervation leading to intractable pruritus in patients with atopic dermatitis. The researchers suggested that a potential explanation for the antipruritic effect of the excimer laser may be secondary to nerve degeneration.³³ Additionally, low doses of UVB light also may inhibit mast cell degranulation and prevent histamine release, further supporting the antipruritic properties of excimer laser.³⁴

In our patient, failed treatment with other modalities led to trial of excimer laser therapy because of the overlapping clinical and histopathologic findings with psoriasis. Excimer laser improved the clinical appearance and overall texture of the ILVEN lesions and decreased pruritus. The reasons for treatment success may be two-fold. By decreasing the number of keratinocytes and mast cells, the excimer laser may have improved the epidermal hyperplasia and pruritus in the ILVEN lesions. Alternatively, because the patient had ILVEN lesions since infancy, psoriasis may have developed in the location of the ILVEN lesions due to koebnerization, resulting in the clinical response to excimer therapy; however, she had no other clinical evidence of psoriasis.

Because of the recalcitrance of ILVEN lesions to conventional therapies, it is important to investigate therapies that may be of possible benefit. Our novel case documents successful use of the excimer laser in the treatment of ILVEN. 

Conclusion

Our case of ILVEN in a woman that had been present since infancy highlights the disease pathology as well as a potential new treatment modality. The patient was refractory to first-line treatments and was concerned about the cosmetic appearance of the lesions. The patient was subsequently treated with a trial of a 308-nm excimer laser with clinical improvement of the lesions. It is possible that the similarity of ILVEN and psoriasis may have contributed to the clinical improvement in our patient, but the mechanism of action remains unknown. Due to the paucity of evidence regarding optimal treatment of ILVEN, the current case offers dermatologists an option for patients who are refractory to other treatments.
 

The Diagnosis: Monsel Solution Reaction

Exogenous substances can cause interesting incongruities in cutaneous biopsies of which pathologists and dermatologists should be cognizant. Exogenous lesions are caused by externally introduced foreign bodies, substances, or materials, such as sterile compressed sponges, aluminum chloride hexahydrate and anhydrous ethyl alcohol, silica, paraffin, and Monsel solution. Monsel solution reaction is a florid fibrohistiocytic proliferation stimulated by the application of Monsel solution. Monsel solution is a ferric subsulfate that often is used to achieve hemostasis after shave biopsies. Hemostasis is thought to result from the ability of ferric ions to denature and agglutinate proteins such as fibrinogen.^1,2 Application of Monsel solution likely causes ferrugination of fibrin, dermal collagen, and striated muscle fibers. Some ferruginated collagen fibers are eliminated through the epidermis as the epidermis regenerates, while some fibers become calcified. Siderophages (iron-containing macrophages) are present in these areas. The ferrugination of collagen fibers becomes less pronounced as the biopsy sites heal and the iron pigment subsequently is absorbed by macrophages. Ferruginated skeletal muscles can act as foreign bodies and may elicit granulomatous reactions.²

It is currently unclear why fibrohistiocytic responses occur in some instances but not others. Iron stains (eg, Perls Prussian blue stain) make interpretation clear, provided the pathologist is familiar with Monsel solution. The primary differential diagnosis of these lesions centers on heavily pigmented melanocytic proliferations. It is critical to review prior biopsy sections or to have definite knowledge of the prior biopsy diagnosis. Histologically, the epidermis may demonstrate nonspecific reactive changes such as hyperkeratosis with foci of irregular acanthosis. The prominent features are present in the dermis where there is a proliferation of spindle- and polyhedral-shaped cells that may show cytologic atypia and occasional mitotic figures. The cells contain refractile brown pigment scattered in the dermis and deposited on collagen fibers (quiz images). Occasional large black or brown encrustations may be identified. Monsel-containing cells may indiscernibly blend with foci of more blatantly fibrohistiocytic differentiation, in which case iron stains are strongly positive (Figure 1). If the clinician uses Monsel solution for hemostasis during the removal of a nevomelanocytic neoplasm, it might be necessary to use melanin stains or immunohistochemistry on the reexcision specimen to distinguish between residual nevomelanocytic and fibrohistiocytic cells.³

Common blue nevus is a benign, typically intradermal melanocytic lesion. It most frequently occurs in young adults and has a predilection for females. Clinically, it can be found anywhere on the body as a single, asymptomatic, well-circumscribed, blue-black, dome-shaped papule measuring less than 1 cm in diameter. Histologically, it is characterized by pigmented, dendritic, spindle-shaped melanocytes that typically are separated by thick collagen bundles (Figure 2). The melanocytes typically have small nuclei with occasional basophilic nucleolus. Melanocytes typically are diffusely positive for melanocytic markers including human melanoma black (HMB) 45, S-100, Melan-A, and microphthalmia transcription factor 1. In contrast to most other benign melanocytic nevi, HMB-45 strongly stains the entire lesion in blue nevi.⁴

Desmoplastic melanoma accounts for 1% to 4% of all melanomas. The median age at diagnosis is 62 years and, as in other types of melanoma, men are more commonly affected.⁵ Clinically, desmoplastic melanoma typically presents on the head and neck as a painless indurated plaque, though it can present as a small papule or nodule. Nearly half of desmoplastic melanomas lack obvious pigmentation, which may lead to the misdiagnosis of basal cell carcinoma or a scar. Histologically, desmoplastic melanomas are composed of spindled melanocytes separated by collagen fibers or fibrous stroma (Figure 3). Histology displays variable cytologic atypia and stromal fibrosis. Characteristically there are small islands of lymphocytes and plasma cells within or at the edge of the tumor. The spindle cells stain positive with S-100 and Sry-related HMg-box gene 10, SOX10. Type IV collagen and laminin often are expressed in desmoplastic melanoma. In contrast to many other subtypes of melanoma, HMB-45 and Melan-A usually are negative.⁶

Animal-type melanoma is a rare neoplasm that differs from other subtypes of melanoma both clinically and histologically. Most frequently, animal-type melanoma affects younger adults (median age, 27 years) and arises on the arms and legs, head and neck, or trunk; men and women are affected equally.7 It most commonly presents with a blue or blue-black nodule with a blue-white veil or irregular white areas. Histologically, animal-type melanoma is a predominantly dermal-based melanocytic proliferation with heavily pigmented epithelioid and spindled melanocytes (Figure 4). The pigmentation pattern ranges widely from fine, granular, light brown deposits to coarse dark brown deposits with malignant cells often arranged in fascicles or sheets. Frequently, there is periadnexal and perieccrine spread. Often, there is epidermal hyperplasia above the dermis. As with conventional melanoma, the immunohistochemistry of animal-type melanoma is positive for S-100 protein, HMB-45, SOX10, and Melan-A.⁷

Recurrent nevi typically arise within 6 months of a previously biopsied melanocytic nevus. Most recurrent nevi originate from common banal nevi (most often a compound nevus). Recurrent nevi also may arise from congenital, atypical/dysplastic, and Spitz nevi. Most often they are found on the back of women aged 20 to 30 years.⁸ Clinically, they manifest as a macular area of scar with variegated hyperpigmentation and hypopigmentation as well as linear streaking. They may demonstrate variable diffuse, stippled, and halo pigmentation patterns. Classically, recurrent nevi present with a trizonal histologic pattern. Within the epidermis there is a proliferation of melanocytes along the dermoepidermal junction, which may show varying degrees of atypia and pagetoid migration. The melanocytes often are described as epithelioid with round nuclei and even chromatin (Figure 5). The atypical features should be confined to the epidermis overlying the prior biopsy site. Within the dermis there is dense dermal collagen and fibrosis with vertically oriented blood vessels. Finally, features of the original nevus may be seen at the base of the lesion. Although immunohistochemistry may be helpful in some cases, an appropriate clinical history and comparison to the prior biopsy can be invaluable.⁸

Host tissue reactions resulting in artefactual changes caused by foreign bodies or substances may confound the untrained eye. Monsel solution reaction may be confused for a blue nevus, desmoplastic melanoma, animal-type melanoma, and a residual/recurrent nevus. This confusion could lead to serious diagnostic errors that could cause an unfavorable outcome for the patient. It is critical to know the salient points in the patient's clinical history. Knowledge of the Monsel solution reaction and other exogenous lesions as well as the subsequent unique tissue reaction patterns can aid in facilitating an accurate and prompt pathologic diagnosis.

The Diagnosis: Monsel Solution Reaction

Exogenous substances can cause interesting incongruities in cutaneous biopsies of which pathologists and dermatologists should be cognizant. Exogenous lesions are caused by externally introduced foreign bodies, substances, or materials, such as sterile compressed sponges, aluminum chloride hexahydrate and anhydrous ethyl alcohol, silica, paraffin, and Monsel solution. Monsel solution reaction is a florid fibrohistiocytic proliferation stimulated by the application of Monsel solution. Monsel solution is a ferric subsulfate that often is used to achieve hemostasis after shave biopsies. Hemostasis is thought to result from the ability of ferric ions to denature and agglutinate proteins such as fibrinogen.^1,2 Application of Monsel solution likely causes ferrugination of fibrin, dermal collagen, and striated muscle fibers. Some ferruginated collagen fibers are eliminated through the epidermis as the epidermis regenerates, while some fibers become calcified. Siderophages (iron-containing macrophages) are present in these areas. The ferrugination of collagen fibers becomes less pronounced as the biopsy sites heal and the iron pigment subsequently is absorbed by macrophages. Ferruginated skeletal muscles can act as foreign bodies and may elicit granulomatous reactions.²

It is currently unclear why fibrohistiocytic responses occur in some instances but not others. Iron stains (eg, Perls Prussian blue stain) make interpretation clear, provided the pathologist is familiar with Monsel solution. The primary differential diagnosis of these lesions centers on heavily pigmented melanocytic proliferations. It is critical to review prior biopsy sections or to have definite knowledge of the prior biopsy diagnosis. Histologically, the epidermis may demonstrate nonspecific reactive changes such as hyperkeratosis with foci of irregular acanthosis. The prominent features are present in the dermis where there is a proliferation of spindle- and polyhedral-shaped cells that may show cytologic atypia and occasional mitotic figures. The cells contain refractile brown pigment scattered in the dermis and deposited on collagen fibers (quiz images). Occasional large black or brown encrustations may be identified. Monsel-containing cells may indiscernibly blend with foci of more blatantly fibrohistiocytic differentiation, in which case iron stains are strongly positive (Figure 1). If the clinician uses Monsel solution for hemostasis during the removal of a nevomelanocytic neoplasm, it might be necessary to use melanin stains or immunohistochemistry on the reexcision specimen to distinguish between residual nevomelanocytic and fibrohistiocytic cells.³

Common blue nevus is a benign, typically intradermal melanocytic lesion. It most frequently occurs in young adults and has a predilection for females. Clinically, it can be found anywhere on the body as a single, asymptomatic, well-circumscribed, blue-black, dome-shaped papule measuring less than 1 cm in diameter. Histologically, it is characterized by pigmented, dendritic, spindle-shaped melanocytes that typically are separated by thick collagen bundles (Figure 2). The melanocytes typically have small nuclei with occasional basophilic nucleolus. Melanocytes typically are diffusely positive for melanocytic markers including human melanoma black (HMB) 45, S-100, Melan-A, and microphthalmia transcription factor 1. In contrast to most other benign melanocytic nevi, HMB-45 strongly stains the entire lesion in blue nevi.⁴

Desmoplastic melanoma accounts for 1% to 4% of all melanomas. The median age at diagnosis is 62 years and, as in other types of melanoma, men are more commonly affected.⁵ Clinically, desmoplastic melanoma typically presents on the head and neck as a painless indurated plaque, though it can present as a small papule or nodule. Nearly half of desmoplastic melanomas lack obvious pigmentation, which may lead to the misdiagnosis of basal cell carcinoma or a scar. Histologically, desmoplastic melanomas are composed of spindled melanocytes separated by collagen fibers or fibrous stroma (Figure 3). Histology displays variable cytologic atypia and stromal fibrosis. Characteristically there are small islands of lymphocytes and plasma cells within or at the edge of the tumor. The spindle cells stain positive with S-100 and Sry-related HMg-box gene 10, SOX10. Type IV collagen and laminin often are expressed in desmoplastic melanoma. In contrast to many other subtypes of melanoma, HMB-45 and Melan-A usually are negative.⁶

Animal-type melanoma is a rare neoplasm that differs from other subtypes of melanoma both clinically and histologically. Most frequently, animal-type melanoma affects younger adults (median age, 27 years) and arises on the arms and legs, head and neck, or trunk; men and women are affected equally.7 It most commonly presents with a blue or blue-black nodule with a blue-white veil or irregular white areas. Histologically, animal-type melanoma is a predominantly dermal-based melanocytic proliferation with heavily pigmented epithelioid and spindled melanocytes (Figure 4). The pigmentation pattern ranges widely from fine, granular, light brown deposits to coarse dark brown deposits with malignant cells often arranged in fascicles or sheets. Frequently, there is periadnexal and perieccrine spread. Often, there is epidermal hyperplasia above the dermis. As with conventional melanoma, the immunohistochemistry of animal-type melanoma is positive for S-100 protein, HMB-45, SOX10, and Melan-A.⁷

Recurrent nevi typically arise within 6 months of a previously biopsied melanocytic nevus. Most recurrent nevi originate from common banal nevi (most often a compound nevus). Recurrent nevi also may arise from congenital, atypical/dysplastic, and Spitz nevi. Most often they are found on the back of women aged 20 to 30 years.⁸ Clinically, they manifest as a macular area of scar with variegated hyperpigmentation and hypopigmentation as well as linear streaking. They may demonstrate variable diffuse, stippled, and halo pigmentation patterns. Classically, recurrent nevi present with a trizonal histologic pattern. Within the epidermis there is a proliferation of melanocytes along the dermoepidermal junction, which may show varying degrees of atypia and pagetoid migration. The melanocytes often are described as epithelioid with round nuclei and even chromatin (Figure 5). The atypical features should be confined to the epidermis overlying the prior biopsy site. Within the dermis there is dense dermal collagen and fibrosis with vertically oriented blood vessels. Finally, features of the original nevus may be seen at the base of the lesion. Although immunohistochemistry may be helpful in some cases, an appropriate clinical history and comparison to the prior biopsy can be invaluable.⁸

Host tissue reactions resulting in artefactual changes caused by foreign bodies or substances may confound the untrained eye. Monsel solution reaction may be confused for a blue nevus, desmoplastic melanoma, animal-type melanoma, and a residual/recurrent nevus. This confusion could lead to serious diagnostic errors that could cause an unfavorable outcome for the patient. It is critical to know the salient points in the patient's clinical history. Knowledge of the Monsel solution reaction and other exogenous lesions as well as the subsequent unique tissue reaction patterns can aid in facilitating an accurate and prompt pathologic diagnosis.

The Diagnosis: Monsel Solution Reaction

Exogenous substances can cause interesting incongruities in cutaneous biopsies of which pathologists and dermatologists should be cognizant. Exogenous lesions are caused by externally introduced foreign bodies, substances, or materials, such as sterile compressed sponges, aluminum chloride hexahydrate and anhydrous ethyl alcohol, silica, paraffin, and Monsel solution. Monsel solution reaction is a florid fibrohistiocytic proliferation stimulated by the application of Monsel solution. Monsel solution is a ferric subsulfate that often is used to achieve hemostasis after shave biopsies. Hemostasis is thought to result from the ability of ferric ions to denature and agglutinate proteins such as fibrinogen.^1,2 Application of Monsel solution likely causes ferrugination of fibrin, dermal collagen, and striated muscle fibers. Some ferruginated collagen fibers are eliminated through the epidermis as the epidermis regenerates, while some fibers become calcified. Siderophages (iron-containing macrophages) are present in these areas. The ferrugination of collagen fibers becomes less pronounced as the biopsy sites heal and the iron pigment subsequently is absorbed by macrophages. Ferruginated skeletal muscles can act as foreign bodies and may elicit granulomatous reactions.²

It is currently unclear why fibrohistiocytic responses occur in some instances but not others. Iron stains (eg, Perls Prussian blue stain) make interpretation clear, provided the pathologist is familiar with Monsel solution. The primary differential diagnosis of these lesions centers on heavily pigmented melanocytic proliferations. It is critical to review prior biopsy sections or to have definite knowledge of the prior biopsy diagnosis. Histologically, the epidermis may demonstrate nonspecific reactive changes such as hyperkeratosis with foci of irregular acanthosis. The prominent features are present in the dermis where there is a proliferation of spindle- and polyhedral-shaped cells that may show cytologic atypia and occasional mitotic figures. The cells contain refractile brown pigment scattered in the dermis and deposited on collagen fibers (quiz images). Occasional large black or brown encrustations may be identified. Monsel-containing cells may indiscernibly blend with foci of more blatantly fibrohistiocytic differentiation, in which case iron stains are strongly positive (Figure 1). If the clinician uses Monsel solution for hemostasis during the removal of a nevomelanocytic neoplasm, it might be necessary to use melanin stains or immunohistochemistry on the reexcision specimen to distinguish between residual nevomelanocytic and fibrohistiocytic cells.³

Common blue nevus is a benign, typically intradermal melanocytic lesion. It most frequently occurs in young adults and has a predilection for females. Clinically, it can be found anywhere on the body as a single, asymptomatic, well-circumscribed, blue-black, dome-shaped papule measuring less than 1 cm in diameter. Histologically, it is characterized by pigmented, dendritic, spindle-shaped melanocytes that typically are separated by thick collagen bundles (Figure 2). The melanocytes typically have small nuclei with occasional basophilic nucleolus. Melanocytes typically are diffusely positive for melanocytic markers including human melanoma black (HMB) 45, S-100, Melan-A, and microphthalmia transcription factor 1. In contrast to most other benign melanocytic nevi, HMB-45 strongly stains the entire lesion in blue nevi.⁴

Desmoplastic melanoma accounts for 1% to 4% of all melanomas. The median age at diagnosis is 62 years and, as in other types of melanoma, men are more commonly affected.⁵ Clinically, desmoplastic melanoma typically presents on the head and neck as a painless indurated plaque, though it can present as a small papule or nodule. Nearly half of desmoplastic melanomas lack obvious pigmentation, which may lead to the misdiagnosis of basal cell carcinoma or a scar. Histologically, desmoplastic melanomas are composed of spindled melanocytes separated by collagen fibers or fibrous stroma (Figure 3). Histology displays variable cytologic atypia and stromal fibrosis. Characteristically there are small islands of lymphocytes and plasma cells within or at the edge of the tumor. The spindle cells stain positive with S-100 and Sry-related HMg-box gene 10, SOX10. Type IV collagen and laminin often are expressed in desmoplastic melanoma. In contrast to many other subtypes of melanoma, HMB-45 and Melan-A usually are negative.⁶

Animal-type melanoma is a rare neoplasm that differs from other subtypes of melanoma both clinically and histologically. Most frequently, animal-type melanoma affects younger adults (median age, 27 years) and arises on the arms and legs, head and neck, or trunk; men and women are affected equally.7 It most commonly presents with a blue or blue-black nodule with a blue-white veil or irregular white areas. Histologically, animal-type melanoma is a predominantly dermal-based melanocytic proliferation with heavily pigmented epithelioid and spindled melanocytes (Figure 4). The pigmentation pattern ranges widely from fine, granular, light brown deposits to coarse dark brown deposits with malignant cells often arranged in fascicles or sheets. Frequently, there is periadnexal and perieccrine spread. Often, there is epidermal hyperplasia above the dermis. As with conventional melanoma, the immunohistochemistry of animal-type melanoma is positive for S-100 protein, HMB-45, SOX10, and Melan-A.⁷

Recurrent nevi typically arise within 6 months of a previously biopsied melanocytic nevus. Most recurrent nevi originate from common banal nevi (most often a compound nevus). Recurrent nevi also may arise from congenital, atypical/dysplastic, and Spitz nevi. Most often they are found on the back of women aged 20 to 30 years.⁸ Clinically, they manifest as a macular area of scar with variegated hyperpigmentation and hypopigmentation as well as linear streaking. They may demonstrate variable diffuse, stippled, and halo pigmentation patterns. Classically, recurrent nevi present with a trizonal histologic pattern. Within the epidermis there is a proliferation of melanocytes along the dermoepidermal junction, which may show varying degrees of atypia and pagetoid migration. The melanocytes often are described as epithelioid with round nuclei and even chromatin (Figure 5). The atypical features should be confined to the epidermis overlying the prior biopsy site. Within the dermis there is dense dermal collagen and fibrosis with vertically oriented blood vessels. Finally, features of the original nevus may be seen at the base of the lesion. Although immunohistochemistry may be helpful in some cases, an appropriate clinical history and comparison to the prior biopsy can be invaluable.⁸

Host tissue reactions resulting in artefactual changes caused by foreign bodies or substances may confound the untrained eye. Monsel solution reaction may be confused for a blue nevus, desmoplastic melanoma, animal-type melanoma, and a residual/recurrent nevus. This confusion could lead to serious diagnostic errors that could cause an unfavorable outcome for the patient. It is critical to know the salient points in the patient's clinical history. Knowledge of the Monsel solution reaction and other exogenous lesions as well as the subsequent unique tissue reaction patterns can aid in facilitating an accurate and prompt pathologic diagnosis.