Imaging

Case

The mother of a 3-year-old boy presented her son to the ED for evaluation after she noticed peeling of the skin in his perianal region. She stated that the peeling had started 1 day prior to presentation. Two days earlier, the mother had brought the same patient to the ED for evaluation of a fever, sore throat, and a slight rash over his face. The boy’s vital signs at the initial presentation were: temperature, 101.8°F; heart rate, 102 beats/minute; and respiratory rate, 28 breaths/minute. Oxygen saturation was 98% on room air.

During this first visit, the mother denied the child having had any fever, chills, headache, sore throat, facial rash, joint pain, or pain on defecation. He had no significant medical history and no known drug allergies. After examination, a throat culture was taken, and the patient was given acetaminophen and discharged home with a diagnosis of viral syndrome.

At the second presentation, physical examination revealed a well-developed child in no distress. The examination was negative except for a 4 x 2 cm area of desquamation present over the perianal region (Figure).

The area of desquamation was dry, mildly erythematous without discharge, and nontender. The patient’s vital signs at this presentation were stable, and he was afebrile. The remaining physical examination findings were normal. The throat culture taken during the first ED presentation was reported as negative. A perianal swab was sent for culture and sensitivity. This was later reported to be positive for group A β-hemolytic streptococci (GABHS), which is sensitive to penicillin. The patient was discharged home in the care of his mother with a prescription of penicillin.  A 10-day follow-up showed complete resolution of the skin rash.

  

Discussion

Perianal streptococcal dermatitis (PSD), which is caused by GABHS, is a frequently overlooked medical entity. Landolt et al¹ investigated the prevalence of PSD at the University Children’s Hospital Basel, Switzerland, from October 2000 to May 2001. In this study, 250 randomly selected patients were studied for signs of PSD by history, examination, and culture, the results of which showed that PSD was frequent in the study cohort. The study further underscored that, to appropriately treat affected patients, signs and symptoms of PSD should be searched for systematically.¹

The rash in this case was most likely the result of scarlet fever with an unusual presentation of PSD; the signs and symptoms of which include perianal erythema, itching, rectal pain, sometimes blood-streaked stools, rectal bleeding, irritation or pruritus, tissue loss and exudation, secondary constipation, and cellulitis. Perianal streptococcal dermatitis has also been described in the adult literature.² As with pediatric cases, PSD in adults is usually caused by GABHS.

Evaluation and Diagnosis

A rapid streptococcal test of suspicious areas can confirm the diagnosis. Fever, sore throat, and arthralgia are rare; however, culture from the perianal region grows GABHS. Titers are usually not elevated in laboratory evaluation. A routine skin culture is an alternative diagnostic aid.

Brilliant² described the bright red color of PSD as a sharply demarcated rash that is caused by GABHS. As previously stated, symptoms include perianal rash, itching, and rectal pain; blood-streaked stools may also be seen in one-third of patients. It primarily occurs in children between 6 months and 10 years of age and is often misdiagnosed and treated inappropriately.³

Prompt diagnosis of GABHS is important. If untreated, it can cause serious systemic infections, especially in elderly and in newborn patients. Treatment with antibiotics resolves the condition in the majority of patients.² In the acute stage, a white pseudomembrane may be present. As the rash becomes more chronic, the perianal eruption may consist of painful fissures, a dry mucoid discharge, or psoriasiform plaques. Perianal dermatitis can also be caused by Staphylococcus aureus or Candida. Confirmation of the diagnosis is accomplished by culturing a moderate-to-heavy growth of GABHS on 5% sheep-blood agar.

Treatment

A 10-day course of oral penicillin produces resolution of the dermatitis and other symptoms in most patients, but a relapse rate as high as 39% has been reported. Other treatment plans include amoxicillin, 40 mg/kg per day, divided into three doses, and/or topical applications of mupirocin 2% three times per day for 10 days. Penicillin, clindamycin phosphate, and erythromycin have also been used.

Although penicillin is generally recommended for treatment of GABHS infection, amoxicillin is often better tolerated in the pediatric population due to its superior palatability. Early antibiotic treatment causes a dramatic and rapid improvement of symptoms. However, according to Olson et al,⁴ PSD initially treated with amoxicillin or penicillin is consistently associated with a high risk of clinical recurrence. Whether treatment with a β-lactamase–resistant agent reduces this risk is uncertain.

 

  

Conclusion

This case represents an unusual presentation of scarlet fever manifesting as perianal dermatitis caused by GABHS. Although more common in the pediatric population, adult cases have been documented in the literature. As this case illustrates, early recognition and treatment with penicillin (or amoxicillin) produces rapid improvement and resolution of symptoms. 

  

---

Dr Nibhanipudi is a professor of clinical emergency medicine at New York Medical College - Metropolitan Hospital Center, New York.

Case

The mother of a 3-year-old boy presented her son to the ED for evaluation after she noticed peeling of the skin in his perianal region. She stated that the peeling had started 1 day prior to presentation. Two days earlier, the mother had brought the same patient to the ED for evaluation of a fever, sore throat, and a slight rash over his face. The boy’s vital signs at the initial presentation were: temperature, 101.8°F; heart rate, 102 beats/minute; and respiratory rate, 28 breaths/minute. Oxygen saturation was 98% on room air.

During this first visit, the mother denied the child having had any fever, chills, headache, sore throat, facial rash, joint pain, or pain on defecation. He had no significant medical history and no known drug allergies. After examination, a throat culture was taken, and the patient was given acetaminophen and discharged home with a diagnosis of viral syndrome.

At the second presentation, physical examination revealed a well-developed child in no distress. The examination was negative except for a 4 x 2 cm area of desquamation present over the perianal region (Figure).

The area of desquamation was dry, mildly erythematous without discharge, and nontender. The patient’s vital signs at this presentation were stable, and he was afebrile. The remaining physical examination findings were normal. The throat culture taken during the first ED presentation was reported as negative. A perianal swab was sent for culture and sensitivity. This was later reported to be positive for group A β-hemolytic streptococci (GABHS), which is sensitive to penicillin. The patient was discharged home in the care of his mother with a prescription of penicillin.  A 10-day follow-up showed complete resolution of the skin rash.

  

Discussion

Perianal streptococcal dermatitis (PSD), which is caused by GABHS, is a frequently overlooked medical entity. Landolt et al¹ investigated the prevalence of PSD at the University Children’s Hospital Basel, Switzerland, from October 2000 to May 2001. In this study, 250 randomly selected patients were studied for signs of PSD by history, examination, and culture, the results of which showed that PSD was frequent in the study cohort. The study further underscored that, to appropriately treat affected patients, signs and symptoms of PSD should be searched for systematically.¹

The rash in this case was most likely the result of scarlet fever with an unusual presentation of PSD; the signs and symptoms of which include perianal erythema, itching, rectal pain, sometimes blood-streaked stools, rectal bleeding, irritation or pruritus, tissue loss and exudation, secondary constipation, and cellulitis. Perianal streptococcal dermatitis has also been described in the adult literature.² As with pediatric cases, PSD in adults is usually caused by GABHS.

Evaluation and Diagnosis

A rapid streptococcal test of suspicious areas can confirm the diagnosis. Fever, sore throat, and arthralgia are rare; however, culture from the perianal region grows GABHS. Titers are usually not elevated in laboratory evaluation. A routine skin culture is an alternative diagnostic aid.

Brilliant² described the bright red color of PSD as a sharply demarcated rash that is caused by GABHS. As previously stated, symptoms include perianal rash, itching, and rectal pain; blood-streaked stools may also be seen in one-third of patients. It primarily occurs in children between 6 months and 10 years of age and is often misdiagnosed and treated inappropriately.³

Prompt diagnosis of GABHS is important. If untreated, it can cause serious systemic infections, especially in elderly and in newborn patients. Treatment with antibiotics resolves the condition in the majority of patients.² In the acute stage, a white pseudomembrane may be present. As the rash becomes more chronic, the perianal eruption may consist of painful fissures, a dry mucoid discharge, or psoriasiform plaques. Perianal dermatitis can also be caused by Staphylococcus aureus or Candida. Confirmation of the diagnosis is accomplished by culturing a moderate-to-heavy growth of GABHS on 5% sheep-blood agar.

Treatment

A 10-day course of oral penicillin produces resolution of the dermatitis and other symptoms in most patients, but a relapse rate as high as 39% has been reported. Other treatment plans include amoxicillin, 40 mg/kg per day, divided into three doses, and/or topical applications of mupirocin 2% three times per day for 10 days. Penicillin, clindamycin phosphate, and erythromycin have also been used.

Although penicillin is generally recommended for treatment of GABHS infection, amoxicillin is often better tolerated in the pediatric population due to its superior palatability. Early antibiotic treatment causes a dramatic and rapid improvement of symptoms. However, according to Olson et al,⁴ PSD initially treated with amoxicillin or penicillin is consistently associated with a high risk of clinical recurrence. Whether treatment with a β-lactamase–resistant agent reduces this risk is uncertain.

 

  

Conclusion

This case represents an unusual presentation of scarlet fever manifesting as perianal dermatitis caused by GABHS. Although more common in the pediatric population, adult cases have been documented in the literature. As this case illustrates, early recognition and treatment with penicillin (or amoxicillin) produces rapid improvement and resolution of symptoms. 

  

---

Dr Nibhanipudi is a professor of clinical emergency medicine at New York Medical College - Metropolitan Hospital Center, New York.

Case

The mother of a 3-year-old boy presented her son to the ED for evaluation after she noticed peeling of the skin in his perianal region. She stated that the peeling had started 1 day prior to presentation. Two days earlier, the mother had brought the same patient to the ED for evaluation of a fever, sore throat, and a slight rash over his face. The boy’s vital signs at the initial presentation were: temperature, 101.8°F; heart rate, 102 beats/minute; and respiratory rate, 28 breaths/minute. Oxygen saturation was 98% on room air.

During this first visit, the mother denied the child having had any fever, chills, headache, sore throat, facial rash, joint pain, or pain on defecation. He had no significant medical history and no known drug allergies. After examination, a throat culture was taken, and the patient was given acetaminophen and discharged home with a diagnosis of viral syndrome.

At the second presentation, physical examination revealed a well-developed child in no distress. The examination was negative except for a 4 x 2 cm area of desquamation present over the perianal region (Figure).

The area of desquamation was dry, mildly erythematous without discharge, and nontender. The patient’s vital signs at this presentation were stable, and he was afebrile. The remaining physical examination findings were normal. The throat culture taken during the first ED presentation was reported as negative. A perianal swab was sent for culture and sensitivity. This was later reported to be positive for group A β-hemolytic streptococci (GABHS), which is sensitive to penicillin. The patient was discharged home in the care of his mother with a prescription of penicillin.  A 10-day follow-up showed complete resolution of the skin rash.

  

Discussion

Perianal streptococcal dermatitis (PSD), which is caused by GABHS, is a frequently overlooked medical entity. Landolt et al¹ investigated the prevalence of PSD at the University Children’s Hospital Basel, Switzerland, from October 2000 to May 2001. In this study, 250 randomly selected patients were studied for signs of PSD by history, examination, and culture, the results of which showed that PSD was frequent in the study cohort. The study further underscored that, to appropriately treat affected patients, signs and symptoms of PSD should be searched for systematically.¹

The rash in this case was most likely the result of scarlet fever with an unusual presentation of PSD; the signs and symptoms of which include perianal erythema, itching, rectal pain, sometimes blood-streaked stools, rectal bleeding, irritation or pruritus, tissue loss and exudation, secondary constipation, and cellulitis. Perianal streptococcal dermatitis has also been described in the adult literature.² As with pediatric cases, PSD in adults is usually caused by GABHS.

Evaluation and Diagnosis

A rapid streptococcal test of suspicious areas can confirm the diagnosis. Fever, sore throat, and arthralgia are rare; however, culture from the perianal region grows GABHS. Titers are usually not elevated in laboratory evaluation. A routine skin culture is an alternative diagnostic aid.

Brilliant² described the bright red color of PSD as a sharply demarcated rash that is caused by GABHS. As previously stated, symptoms include perianal rash, itching, and rectal pain; blood-streaked stools may also be seen in one-third of patients. It primarily occurs in children between 6 months and 10 years of age and is often misdiagnosed and treated inappropriately.³

Prompt diagnosis of GABHS is important. If untreated, it can cause serious systemic infections, especially in elderly and in newborn patients. Treatment with antibiotics resolves the condition in the majority of patients.² In the acute stage, a white pseudomembrane may be present. As the rash becomes more chronic, the perianal eruption may consist of painful fissures, a dry mucoid discharge, or psoriasiform plaques. Perianal dermatitis can also be caused by Staphylococcus aureus or Candida. Confirmation of the diagnosis is accomplished by culturing a moderate-to-heavy growth of GABHS on 5% sheep-blood agar.

Treatment

A 10-day course of oral penicillin produces resolution of the dermatitis and other symptoms in most patients, but a relapse rate as high as 39% has been reported. Other treatment plans include amoxicillin, 40 mg/kg per day, divided into three doses, and/or topical applications of mupirocin 2% three times per day for 10 days. Penicillin, clindamycin phosphate, and erythromycin have also been used.

Although penicillin is generally recommended for treatment of GABHS infection, amoxicillin is often better tolerated in the pediatric population due to its superior palatability. Early antibiotic treatment causes a dramatic and rapid improvement of symptoms. However, according to Olson et al,⁴ PSD initially treated with amoxicillin or penicillin is consistently associated with a high risk of clinical recurrence. Whether treatment with a β-lactamase–resistant agent reduces this risk is uncertain.

 

  

Conclusion

This case represents an unusual presentation of scarlet fever manifesting as perianal dermatitis caused by GABHS. Although more common in the pediatric population, adult cases have been documented in the literature. As this case illustrates, early recognition and treatment with penicillin (or amoxicillin) produces rapid improvement and resolution of symptoms. 

  

---

Dr Nibhanipudi is a professor of clinical emergency medicine at New York Medical College - Metropolitan Hospital Center, New York.

 A bone island is a focus of normal cortical bone located within the medullary cavity. The vast majority of bone islands are small, measuring from 1 mm to 2 cm in size. They are found more frequently in adults than in children. The lesion can be virtually diagnosed on the basis of its characteristic clinical and imaging features. Differential diagnosis may be difficult when the lesion manifests itself uncharacteristically by being symptomatic, very large, and hot on bone scan.^1-4

The term giant bone island has been used to describe a large lesion1 that measures more than 2 cm in any dimension.⁵ Giant bone islands have been described only in adults,^1,5-15 and the longest bone island length reported is 10.5 cm.¹⁰ They are usually symptomatic and associated with increased radionuclide uptake on bone scintigraphy.¹⁴

The history and the clinical and imaging presentation of an even longer, symptomatic, and scintigraphically hot lesion in the tibial diaphysis of a 10-year-old boy is reported. The lesion further exhibited several atypical imaging features necessitating an open biopsy, which confirmed the diagnosis of a giant bone island. The pertinent differential diagnosis and the clinical and radiographic findings after 15-year follow-up are also presented and discussed. The patient provided written informed consent for print and electronic publication of this case report.

Case Report

A 10-year-old boy was admitted for surgical repair of an inguinal hernia. Physical examination revealed a painless but tender anterior bowing of the right tibial diaphysis. The patient was a healthy-appearing white male with normal vital signs, gait, and posture. His parents noticed a slight protuberance of the tibia at age 2.5 years. No medical advice was asked for the bone swelling after that time. After recovery from the inguinal hernia repair 3 weeks later, the bone lesion was thoroughly examined. Radiographs showed an oblong, homogenous region of dense sclerosis in the diaphysis of the right tibia. The lesion had relatively well-defined margins and was located in the medullary cavity. Speculations were not obvious in the periphery of the lesion, which exhibited a sharp circumscription (Figures 1A, 1B). A well-defined lytic area was evident at the distal part of the lesion (Figure 1B). There was no periosteal reaction. Blood and serum chemistries were within normal limits, including serum calcium, phosphorus, and alkaline phosphatase. A conventional 3-phase bone scintigraphy (300 MBq) with technetium-99m HDP (hydroxydiphosphonate) indicated increased uptake in the area of the lesion but no other skeletal abnormality (Figure 2). Computed tomography (CT) showed that the lesion was purely intramedullary and densely blastic. The lesion originated from the medial cortex, which was thickened (Figure 3A). The lesion extended to the anterolateral cortex, which was thinned and included a lytic area. In the distal part of the lesion, the anterolateral cortex was thickened, included lytic areas, and exhibited an anterior portion of cortical destruction (Figure 3B). The fatty marrow adjacent to the region of sclerosis appeared normal. There was no evidence of extraosseous soft-tissue changes. On both T1- and T2-weighted magnetic resonance imaging (MRI), the lesion exhibited low-signal intensity. The lesion measured 10.8×2.2×1 cm. It originated from the medial cortical bone of the tibia, blended into the medullary cavity, and extended anteriorly towards and through the anterior cortex. The area of cortical destruction was clearly evident on the axial MRI. The periosteum was displaced and eroded anteriorly by focal radiating bony streaks. No enhancement was seen after the intravenous administration of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) as a contrast medium. There were no extraosseous soft-tissue changes. In the distal part of the lesion, sagittal and axial MRI showed a 1.2×0.8×0.7-cm well-defined ovoid focus, with characteristics of cystic degeneration that exhibited intermediate-signal intensity on T1-weighted MRI (Figure 4) and high-signal intensity on T2-weighted MRI.

 

 

An open biopsy was performed. Macroscopically, a wedge of compact bone measuring 3×1.7×0.6 cm was taken. Microscopic examination showed a thinned periphery of lamellar (mature) bone with haversian canals and, beneath it, woven (immature) bone with long-surface processes projecting within adjacent cancellous bone (Figure 5A). The woven bone contained loose vascular fibrous tissue. No osteoclasts were noted, and the very few osteoblasts lining the bone trabeculae were small, single-layered, and flat (Figure 5B). There was no evidence of neoplastic cells. There was no abnormality of the periosteum and the surrounding soft tissues.

The histology was pathognomonic of a giant bone island. No additional surgical intervention was recommended.

The postoperative course was uncomplicated, and the patient was discharged 2 weeks later. An above-the-knee plaster was recommended for 3 months and a below-the-knee splint for an additional 2-month period. Full weight-bearing was allowed only after the postsurgical sixth month to prevent an impending fracture. The tibial bowing was tender to pressure or palpation, and the patient reported mild spontaneous pain during follow-up. Radiographs 1 year after surgery indicated that the bone area removed for biopsy was replaced by compact bone. MRI performed 4 years after surgery showed that the volume of the lesion in relation to the host bone was not changed.

 

At the last follow-up 15 years after surgery, the anterior tibial bowing was not changed (Figure 6A), but the patient additionally complained of skin irritation after intense training wearing boots during military service. The radiographic appearance of the lesion was also not changed, while the periphery of the lesion exhibited scarce radiating bony streaks with rounded contours (Figures 6B, 6C). The clinical symptoms and signs from wearing military boots completely subsided after a couple of weeks’ rest from daily army activities, but the mild spontaneous pain and the local tenderness over the tibial bowing persisted.

Discussion

Giant bone islands are more likely to be associated with clinical symptoms than the usual small-sized bone island. Some degree of pain was detected in 8 of 10 patients with a giant bone island presented in the literature, but it was induced by trauma in 3 of them.¹⁴

Radiographic appearance is among the distinguishing diagnostic features of a giant bone island. It appears as an ovoid, round, or oblong, homogenously dense, single or multiple focus of sclerosis within the medullary cavity; it is oriented along the long axis of the host bone, and it exhibits peripheral pseudopodia or radiating spicules producing the typical “thorny” or “paintbrush” appearance.^8,16,17 It does not exhibit cortical penetration and it is not associated with periosteal reaction.10

The CT findings include a sclerotic and hyperdense focus with spiculated margins extending into the adjacent cancellous bone. The lack of bone destruction and soft-tissue mass are also diagnostic.^3,7 MRI findings will reflect the low-signal intensity characteristics of cortical bone on all pulse sequences.¹⁸

Enostoses usually exhibit no activity on skeletal scintigraphy, while giant lesions generally show increased radiotracer uptake.^{5,9-11,14,19-27} The latter may result from the increased amount of bone turnover, which is seen more often with larger lesions because of active bone deposition and remodeling.^20,21,23,28 Histopathology of a giant bone island appears identical to the well-described pathologic appearance of smaller bone islands. The lesion is composed of compact lamellar bone and haversian systems, which blend with the adjacent spongiosa. The surrounding cancellous bone forms thorn-like trabeculae radiating from the lesion and merging with the cancellous bone.^1,4,5,8,28

The presumptive diagnosis of a bone island is based on the clinical findings, imaging features, and follow-up examinations. An asymptomatic, isolated, sclerotic bone lesion showing the typical features of a bone island on plain radiography, CT, and MRI, whatever its size, that is nonactive on bone scan may be easily diagnosed. However, a symptomatic patient with a hot lesion on scintigraphy should be carefully observed. In addition, larger lesions may raise the suspicion of a neoplasm, such as a sclerotic variant of osteosarcoma. In such cases, an open biopsy may be undertaken. No specific treatment is required after the diagnosis has been confirmed. There is no literature to suggest that, after adequate biopsy confirmation, excision or resection is necessary. Follow-up radiographic examination of the lesion should be suggested to monitor for any potential growth.^2,10,23

The first giant bone island appearing in a child is presented in this report. The lack of a causative factor leading to the anterior tibial bowing indicated that the bone deformity was caused primarily by the lesion. The present case is unusual for the appearance of several atypical features, some of which have not been previously described. Peripheral radiating spiculated margin was absent on the patient’s initial radiographs and CT imaging. MRI indicated only the presence of radiating bony streaks that displaced and eroded the periosteum on the anterior border of the lesion. The CT findings that the lesion likely originated or was in close proximity with the medial cortex of the tibia were also atypical. It has been previously reported that spinal lesions located immediately below the cortex tend to fuse with the endosteal surface, while similar features may also be seen in the appendicular enostoses.^4,29 Other CT findings, such as the thinning of the overlying anterolateral cortical bone, as well as the cortical thickening at the periphery of the lesion associated with areas of soft-tissue attenuation and anterior cortical destruction, have not been described even in the atypical features of a giant bone island. The lytic area resembling a nidus that was evident at the distal part of the lesion was more likely consistent with an area of resorption, which, although rare, has been described on giant lesions.^2,9,29 The substantial amount of woven bone transforming to lamellar bone that was evident in the present patient’s microscopic features is also an atypical finding, although it may be expected to some degree in scintigraphically hot, large lesions.²⁸ The clinical and imaging progress of the lesion supported the diagnosis of a giant bone island. The degree of the anterior tibial bowing and the volume of the lesion in relation to the host bone were not changed throughout the follow-up period, indicating that the growth of the lesion followed the growth of the normal bone.

 

The differential diagnosis of a giant bone island includes a variety of benign tumors and tumor-like lesions, as well as malignant bone lesions.^{2,4,23,28,30,31} In the patient presented in this report, the diagnosis of an atypical sclerotic presentation of a nonossifying fibroma or healing stage of this lesion could be consistent with some of the CT findings, including the eccentric origin from the cortex associated with medial cortical thickening, the anterolateral cortical thinning, and the soft-tissue attenuation of cortical areas. In addition, unifocal osteofibrous dysplasia may also present with a long intracortical diaphyseal lucency within an area of marked cortical sclerosis and cause a bowing deformity. Both diagnoses were excluded, since no fibrous stroma was evident on the histologic examination of the lesion. A large or giant long-bone osteoma would be associated with the outer cortical margin of bone but would not involve the intramedullary space. The scintigraphically increased uptake of radioisotope, as well as the CT and MRI findings, were not consistent with the diagnosis of osteoid osteoma, osteoblastoma, or osteomyelitis. Although most imaging findings were consistent with a benign lesion, and contrast-enhanced MRI showed no increased vascularity, anterior cortical disruption necessitated a bone biopsy to rule out any potential malignancy.

The histopathology in association with the clinical and imaging findings indicated the diagnosis of a giant bone island. The increased proportion of maturing woven bone over lamellar bone indicated an active remodeling lesion that could be related to the patient’s age, since the clinical and radiographic features of the lesion were not changed after 15-year follow-up.

Conclusion

This is the first giant bone island diagnosed in a patient before puberty. Its greatest length was 10.8 cm, which is the longest reported in the literature. The imaging appearance included several atypical features that are very rare or have not been reported. Microscopic features indicated less mature lamellar bone and a prominent proportion of maturing woven bone. The clinical and the radiographic appearance of the lesion were not changed after 15-year follow-up.

 A bone island is a focus of normal cortical bone located within the medullary cavity. The vast majority of bone islands are small, measuring from 1 mm to 2 cm in size. They are found more frequently in adults than in children. The lesion can be virtually diagnosed on the basis of its characteristic clinical and imaging features. Differential diagnosis may be difficult when the lesion manifests itself uncharacteristically by being symptomatic, very large, and hot on bone scan.^1-4

The term giant bone island has been used to describe a large lesion1 that measures more than 2 cm in any dimension.⁵ Giant bone islands have been described only in adults,^1,5-15 and the longest bone island length reported is 10.5 cm.¹⁰ They are usually symptomatic and associated with increased radionuclide uptake on bone scintigraphy.¹⁴

The history and the clinical and imaging presentation of an even longer, symptomatic, and scintigraphically hot lesion in the tibial diaphysis of a 10-year-old boy is reported. The lesion further exhibited several atypical imaging features necessitating an open biopsy, which confirmed the diagnosis of a giant bone island. The pertinent differential diagnosis and the clinical and radiographic findings after 15-year follow-up are also presented and discussed. The patient provided written informed consent for print and electronic publication of this case report.

Case Report

A 10-year-old boy was admitted for surgical repair of an inguinal hernia. Physical examination revealed a painless but tender anterior bowing of the right tibial diaphysis. The patient was a healthy-appearing white male with normal vital signs, gait, and posture. His parents noticed a slight protuberance of the tibia at age 2.5 years. No medical advice was asked for the bone swelling after that time. After recovery from the inguinal hernia repair 3 weeks later, the bone lesion was thoroughly examined. Radiographs showed an oblong, homogenous region of dense sclerosis in the diaphysis of the right tibia. The lesion had relatively well-defined margins and was located in the medullary cavity. Speculations were not obvious in the periphery of the lesion, which exhibited a sharp circumscription (Figures 1A, 1B). A well-defined lytic area was evident at the distal part of the lesion (Figure 1B). There was no periosteal reaction. Blood and serum chemistries were within normal limits, including serum calcium, phosphorus, and alkaline phosphatase. A conventional 3-phase bone scintigraphy (300 MBq) with technetium-99m HDP (hydroxydiphosphonate) indicated increased uptake in the area of the lesion but no other skeletal abnormality (Figure 2). Computed tomography (CT) showed that the lesion was purely intramedullary and densely blastic. The lesion originated from the medial cortex, which was thickened (Figure 3A). The lesion extended to the anterolateral cortex, which was thinned and included a lytic area. In the distal part of the lesion, the anterolateral cortex was thickened, included lytic areas, and exhibited an anterior portion of cortical destruction (Figure 3B). The fatty marrow adjacent to the region of sclerosis appeared normal. There was no evidence of extraosseous soft-tissue changes. On both T1- and T2-weighted magnetic resonance imaging (MRI), the lesion exhibited low-signal intensity. The lesion measured 10.8×2.2×1 cm. It originated from the medial cortical bone of the tibia, blended into the medullary cavity, and extended anteriorly towards and through the anterior cortex. The area of cortical destruction was clearly evident on the axial MRI. The periosteum was displaced and eroded anteriorly by focal radiating bony streaks. No enhancement was seen after the intravenous administration of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) as a contrast medium. There were no extraosseous soft-tissue changes. In the distal part of the lesion, sagittal and axial MRI showed a 1.2×0.8×0.7-cm well-defined ovoid focus, with characteristics of cystic degeneration that exhibited intermediate-signal intensity on T1-weighted MRI (Figure 4) and high-signal intensity on T2-weighted MRI.

 

 

An open biopsy was performed. Macroscopically, a wedge of compact bone measuring 3×1.7×0.6 cm was taken. Microscopic examination showed a thinned periphery of lamellar (mature) bone with haversian canals and, beneath it, woven (immature) bone with long-surface processes projecting within adjacent cancellous bone (Figure 5A). The woven bone contained loose vascular fibrous tissue. No osteoclasts were noted, and the very few osteoblasts lining the bone trabeculae were small, single-layered, and flat (Figure 5B). There was no evidence of neoplastic cells. There was no abnormality of the periosteum and the surrounding soft tissues.

The histology was pathognomonic of a giant bone island. No additional surgical intervention was recommended.

The postoperative course was uncomplicated, and the patient was discharged 2 weeks later. An above-the-knee plaster was recommended for 3 months and a below-the-knee splint for an additional 2-month period. Full weight-bearing was allowed only after the postsurgical sixth month to prevent an impending fracture. The tibial bowing was tender to pressure or palpation, and the patient reported mild spontaneous pain during follow-up. Radiographs 1 year after surgery indicated that the bone area removed for biopsy was replaced by compact bone. MRI performed 4 years after surgery showed that the volume of the lesion in relation to the host bone was not changed.

 

At the last follow-up 15 years after surgery, the anterior tibial bowing was not changed (Figure 6A), but the patient additionally complained of skin irritation after intense training wearing boots during military service. The radiographic appearance of the lesion was also not changed, while the periphery of the lesion exhibited scarce radiating bony streaks with rounded contours (Figures 6B, 6C). The clinical symptoms and signs from wearing military boots completely subsided after a couple of weeks’ rest from daily army activities, but the mild spontaneous pain and the local tenderness over the tibial bowing persisted.

Discussion

Giant bone islands are more likely to be associated with clinical symptoms than the usual small-sized bone island. Some degree of pain was detected in 8 of 10 patients with a giant bone island presented in the literature, but it was induced by trauma in 3 of them.¹⁴

Radiographic appearance is among the distinguishing diagnostic features of a giant bone island. It appears as an ovoid, round, or oblong, homogenously dense, single or multiple focus of sclerosis within the medullary cavity; it is oriented along the long axis of the host bone, and it exhibits peripheral pseudopodia or radiating spicules producing the typical “thorny” or “paintbrush” appearance.^8,16,17 It does not exhibit cortical penetration and it is not associated with periosteal reaction.10

The CT findings include a sclerotic and hyperdense focus with spiculated margins extending into the adjacent cancellous bone. The lack of bone destruction and soft-tissue mass are also diagnostic.^3,7 MRI findings will reflect the low-signal intensity characteristics of cortical bone on all pulse sequences.¹⁸

Enostoses usually exhibit no activity on skeletal scintigraphy, while giant lesions generally show increased radiotracer uptake.^{5,9-11,14,19-27} The latter may result from the increased amount of bone turnover, which is seen more often with larger lesions because of active bone deposition and remodeling.^20,21,23,28 Histopathology of a giant bone island appears identical to the well-described pathologic appearance of smaller bone islands. The lesion is composed of compact lamellar bone and haversian systems, which blend with the adjacent spongiosa. The surrounding cancellous bone forms thorn-like trabeculae radiating from the lesion and merging with the cancellous bone.^1,4,5,8,28

The presumptive diagnosis of a bone island is based on the clinical findings, imaging features, and follow-up examinations. An asymptomatic, isolated, sclerotic bone lesion showing the typical features of a bone island on plain radiography, CT, and MRI, whatever its size, that is nonactive on bone scan may be easily diagnosed. However, a symptomatic patient with a hot lesion on scintigraphy should be carefully observed. In addition, larger lesions may raise the suspicion of a neoplasm, such as a sclerotic variant of osteosarcoma. In such cases, an open biopsy may be undertaken. No specific treatment is required after the diagnosis has been confirmed. There is no literature to suggest that, after adequate biopsy confirmation, excision or resection is necessary. Follow-up radiographic examination of the lesion should be suggested to monitor for any potential growth.^2,10,23

The first giant bone island appearing in a child is presented in this report. The lack of a causative factor leading to the anterior tibial bowing indicated that the bone deformity was caused primarily by the lesion. The present case is unusual for the appearance of several atypical features, some of which have not been previously described. Peripheral radiating spiculated margin was absent on the patient’s initial radiographs and CT imaging. MRI indicated only the presence of radiating bony streaks that displaced and eroded the periosteum on the anterior border of the lesion. The CT findings that the lesion likely originated or was in close proximity with the medial cortex of the tibia were also atypical. It has been previously reported that spinal lesions located immediately below the cortex tend to fuse with the endosteal surface, while similar features may also be seen in the appendicular enostoses.^4,29 Other CT findings, such as the thinning of the overlying anterolateral cortical bone, as well as the cortical thickening at the periphery of the lesion associated with areas of soft-tissue attenuation and anterior cortical destruction, have not been described even in the atypical features of a giant bone island. The lytic area resembling a nidus that was evident at the distal part of the lesion was more likely consistent with an area of resorption, which, although rare, has been described on giant lesions.^2,9,29 The substantial amount of woven bone transforming to lamellar bone that was evident in the present patient’s microscopic features is also an atypical finding, although it may be expected to some degree in scintigraphically hot, large lesions.²⁸ The clinical and imaging progress of the lesion supported the diagnosis of a giant bone island. The degree of the anterior tibial bowing and the volume of the lesion in relation to the host bone were not changed throughout the follow-up period, indicating that the growth of the lesion followed the growth of the normal bone.

 

The differential diagnosis of a giant bone island includes a variety of benign tumors and tumor-like lesions, as well as malignant bone lesions.^{2,4,23,28,30,31} In the patient presented in this report, the diagnosis of an atypical sclerotic presentation of a nonossifying fibroma or healing stage of this lesion could be consistent with some of the CT findings, including the eccentric origin from the cortex associated with medial cortical thickening, the anterolateral cortical thinning, and the soft-tissue attenuation of cortical areas. In addition, unifocal osteofibrous dysplasia may also present with a long intracortical diaphyseal lucency within an area of marked cortical sclerosis and cause a bowing deformity. Both diagnoses were excluded, since no fibrous stroma was evident on the histologic examination of the lesion. A large or giant long-bone osteoma would be associated with the outer cortical margin of bone but would not involve the intramedullary space. The scintigraphically increased uptake of radioisotope, as well as the CT and MRI findings, were not consistent with the diagnosis of osteoid osteoma, osteoblastoma, or osteomyelitis. Although most imaging findings were consistent with a benign lesion, and contrast-enhanced MRI showed no increased vascularity, anterior cortical disruption necessitated a bone biopsy to rule out any potential malignancy.

The histopathology in association with the clinical and imaging findings indicated the diagnosis of a giant bone island. The increased proportion of maturing woven bone over lamellar bone indicated an active remodeling lesion that could be related to the patient’s age, since the clinical and radiographic features of the lesion were not changed after 15-year follow-up.

Conclusion

This is the first giant bone island diagnosed in a patient before puberty. Its greatest length was 10.8 cm, which is the longest reported in the literature. The imaging appearance included several atypical features that are very rare or have not been reported. Microscopic features indicated less mature lamellar bone and a prominent proportion of maturing woven bone. The clinical and the radiographic appearance of the lesion were not changed after 15-year follow-up.

 A bone island is a focus of normal cortical bone located within the medullary cavity. The vast majority of bone islands are small, measuring from 1 mm to 2 cm in size. They are found more frequently in adults than in children. The lesion can be virtually diagnosed on the basis of its characteristic clinical and imaging features. Differential diagnosis may be difficult when the lesion manifests itself uncharacteristically by being symptomatic, very large, and hot on bone scan.^1-4

The term giant bone island has been used to describe a large lesion1 that measures more than 2 cm in any dimension.⁵ Giant bone islands have been described only in adults,^1,5-15 and the longest bone island length reported is 10.5 cm.¹⁰ They are usually symptomatic and associated with increased radionuclide uptake on bone scintigraphy.¹⁴

The history and the clinical and imaging presentation of an even longer, symptomatic, and scintigraphically hot lesion in the tibial diaphysis of a 10-year-old boy is reported. The lesion further exhibited several atypical imaging features necessitating an open biopsy, which confirmed the diagnosis of a giant bone island. The pertinent differential diagnosis and the clinical and radiographic findings after 15-year follow-up are also presented and discussed. The patient provided written informed consent for print and electronic publication of this case report.

Case Report

A 10-year-old boy was admitted for surgical repair of an inguinal hernia. Physical examination revealed a painless but tender anterior bowing of the right tibial diaphysis. The patient was a healthy-appearing white male with normal vital signs, gait, and posture. His parents noticed a slight protuberance of the tibia at age 2.5 years. No medical advice was asked for the bone swelling after that time. After recovery from the inguinal hernia repair 3 weeks later, the bone lesion was thoroughly examined. Radiographs showed an oblong, homogenous region of dense sclerosis in the diaphysis of the right tibia. The lesion had relatively well-defined margins and was located in the medullary cavity. Speculations were not obvious in the periphery of the lesion, which exhibited a sharp circumscription (Figures 1A, 1B). A well-defined lytic area was evident at the distal part of the lesion (Figure 1B). There was no periosteal reaction. Blood and serum chemistries were within normal limits, including serum calcium, phosphorus, and alkaline phosphatase. A conventional 3-phase bone scintigraphy (300 MBq) with technetium-99m HDP (hydroxydiphosphonate) indicated increased uptake in the area of the lesion but no other skeletal abnormality (Figure 2). Computed tomography (CT) showed that the lesion was purely intramedullary and densely blastic. The lesion originated from the medial cortex, which was thickened (Figure 3A). The lesion extended to the anterolateral cortex, which was thinned and included a lytic area. In the distal part of the lesion, the anterolateral cortex was thickened, included lytic areas, and exhibited an anterior portion of cortical destruction (Figure 3B). The fatty marrow adjacent to the region of sclerosis appeared normal. There was no evidence of extraosseous soft-tissue changes. On both T1- and T2-weighted magnetic resonance imaging (MRI), the lesion exhibited low-signal intensity. The lesion measured 10.8×2.2×1 cm. It originated from the medial cortical bone of the tibia, blended into the medullary cavity, and extended anteriorly towards and through the anterior cortex. The area of cortical destruction was clearly evident on the axial MRI. The periosteum was displaced and eroded anteriorly by focal radiating bony streaks. No enhancement was seen after the intravenous administration of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) as a contrast medium. There were no extraosseous soft-tissue changes. In the distal part of the lesion, sagittal and axial MRI showed a 1.2×0.8×0.7-cm well-defined ovoid focus, with characteristics of cystic degeneration that exhibited intermediate-signal intensity on T1-weighted MRI (Figure 4) and high-signal intensity on T2-weighted MRI.

 

 

An open biopsy was performed. Macroscopically, a wedge of compact bone measuring 3×1.7×0.6 cm was taken. Microscopic examination showed a thinned periphery of lamellar (mature) bone with haversian canals and, beneath it, woven (immature) bone with long-surface processes projecting within adjacent cancellous bone (Figure 5A). The woven bone contained loose vascular fibrous tissue. No osteoclasts were noted, and the very few osteoblasts lining the bone trabeculae were small, single-layered, and flat (Figure 5B). There was no evidence of neoplastic cells. There was no abnormality of the periosteum and the surrounding soft tissues.

The histology was pathognomonic of a giant bone island. No additional surgical intervention was recommended.

The postoperative course was uncomplicated, and the patient was discharged 2 weeks later. An above-the-knee plaster was recommended for 3 months and a below-the-knee splint for an additional 2-month period. Full weight-bearing was allowed only after the postsurgical sixth month to prevent an impending fracture. The tibial bowing was tender to pressure or palpation, and the patient reported mild spontaneous pain during follow-up. Radiographs 1 year after surgery indicated that the bone area removed for biopsy was replaced by compact bone. MRI performed 4 years after surgery showed that the volume of the lesion in relation to the host bone was not changed.

 

At the last follow-up 15 years after surgery, the anterior tibial bowing was not changed (Figure 6A), but the patient additionally complained of skin irritation after intense training wearing boots during military service. The radiographic appearance of the lesion was also not changed, while the periphery of the lesion exhibited scarce radiating bony streaks with rounded contours (Figures 6B, 6C). The clinical symptoms and signs from wearing military boots completely subsided after a couple of weeks’ rest from daily army activities, but the mild spontaneous pain and the local tenderness over the tibial bowing persisted.

Discussion

Giant bone islands are more likely to be associated with clinical symptoms than the usual small-sized bone island. Some degree of pain was detected in 8 of 10 patients with a giant bone island presented in the literature, but it was induced by trauma in 3 of them.¹⁴

Radiographic appearance is among the distinguishing diagnostic features of a giant bone island. It appears as an ovoid, round, or oblong, homogenously dense, single or multiple focus of sclerosis within the medullary cavity; it is oriented along the long axis of the host bone, and it exhibits peripheral pseudopodia or radiating spicules producing the typical “thorny” or “paintbrush” appearance.^8,16,17 It does not exhibit cortical penetration and it is not associated with periosteal reaction.10

The CT findings include a sclerotic and hyperdense focus with spiculated margins extending into the adjacent cancellous bone. The lack of bone destruction and soft-tissue mass are also diagnostic.^3,7 MRI findings will reflect the low-signal intensity characteristics of cortical bone on all pulse sequences.¹⁸

Enostoses usually exhibit no activity on skeletal scintigraphy, while giant lesions generally show increased radiotracer uptake.^{5,9-11,14,19-27} The latter may result from the increased amount of bone turnover, which is seen more often with larger lesions because of active bone deposition and remodeling.^20,21,23,28 Histopathology of a giant bone island appears identical to the well-described pathologic appearance of smaller bone islands. The lesion is composed of compact lamellar bone and haversian systems, which blend with the adjacent spongiosa. The surrounding cancellous bone forms thorn-like trabeculae radiating from the lesion and merging with the cancellous bone.^1,4,5,8,28

The presumptive diagnosis of a bone island is based on the clinical findings, imaging features, and follow-up examinations. An asymptomatic, isolated, sclerotic bone lesion showing the typical features of a bone island on plain radiography, CT, and MRI, whatever its size, that is nonactive on bone scan may be easily diagnosed. However, a symptomatic patient with a hot lesion on scintigraphy should be carefully observed. In addition, larger lesions may raise the suspicion of a neoplasm, such as a sclerotic variant of osteosarcoma. In such cases, an open biopsy may be undertaken. No specific treatment is required after the diagnosis has been confirmed. There is no literature to suggest that, after adequate biopsy confirmation, excision or resection is necessary. Follow-up radiographic examination of the lesion should be suggested to monitor for any potential growth.^2,10,23

The first giant bone island appearing in a child is presented in this report. The lack of a causative factor leading to the anterior tibial bowing indicated that the bone deformity was caused primarily by the lesion. The present case is unusual for the appearance of several atypical features, some of which have not been previously described. Peripheral radiating spiculated margin was absent on the patient’s initial radiographs and CT imaging. MRI indicated only the presence of radiating bony streaks that displaced and eroded the periosteum on the anterior border of the lesion. The CT findings that the lesion likely originated or was in close proximity with the medial cortex of the tibia were also atypical. It has been previously reported that spinal lesions located immediately below the cortex tend to fuse with the endosteal surface, while similar features may also be seen in the appendicular enostoses.^4,29 Other CT findings, such as the thinning of the overlying anterolateral cortical bone, as well as the cortical thickening at the periphery of the lesion associated with areas of soft-tissue attenuation and anterior cortical destruction, have not been described even in the atypical features of a giant bone island. The lytic area resembling a nidus that was evident at the distal part of the lesion was more likely consistent with an area of resorption, which, although rare, has been described on giant lesions.^2,9,29 The substantial amount of woven bone transforming to lamellar bone that was evident in the present patient’s microscopic features is also an atypical finding, although it may be expected to some degree in scintigraphically hot, large lesions.²⁸ The clinical and imaging progress of the lesion supported the diagnosis of a giant bone island. The degree of the anterior tibial bowing and the volume of the lesion in relation to the host bone were not changed throughout the follow-up period, indicating that the growth of the lesion followed the growth of the normal bone.

 

The differential diagnosis of a giant bone island includes a variety of benign tumors and tumor-like lesions, as well as malignant bone lesions.^{2,4,23,28,30,31} In the patient presented in this report, the diagnosis of an atypical sclerotic presentation of a nonossifying fibroma or healing stage of this lesion could be consistent with some of the CT findings, including the eccentric origin from the cortex associated with medial cortical thickening, the anterolateral cortical thinning, and the soft-tissue attenuation of cortical areas. In addition, unifocal osteofibrous dysplasia may also present with a long intracortical diaphyseal lucency within an area of marked cortical sclerosis and cause a bowing deformity. Both diagnoses were excluded, since no fibrous stroma was evident on the histologic examination of the lesion. A large or giant long-bone osteoma would be associated with the outer cortical margin of bone but would not involve the intramedullary space. The scintigraphically increased uptake of radioisotope, as well as the CT and MRI findings, were not consistent with the diagnosis of osteoid osteoma, osteoblastoma, or osteomyelitis. Although most imaging findings were consistent with a benign lesion, and contrast-enhanced MRI showed no increased vascularity, anterior cortical disruption necessitated a bone biopsy to rule out any potential malignancy.

The histopathology in association with the clinical and imaging findings indicated the diagnosis of a giant bone island. The increased proportion of maturing woven bone over lamellar bone indicated an active remodeling lesion that could be related to the patient’s age, since the clinical and radiographic features of the lesion were not changed after 15-year follow-up.

Conclusion

This is the first giant bone island diagnosed in a patient before puberty. Its greatest length was 10.8 cm, which is the longest reported in the literature. The imaging appearance included several atypical features that are very rare or have not been reported. Microscopic features indicated less mature lamellar bone and a prominent proportion of maturing woven bone. The clinical and the radiographic appearance of the lesion were not changed after 15-year follow-up.

The apparent increase in the prevalence of incidental pancreatic cysts in recent years may be tied to improvements in MRI scanning technology, results of a study suggest.

Researchers conducted a retrospective analysis of data from 500 patients who underwent an MRI for nonpancreatic indications at a single center between 2005 and 2014; 50 were sampled from each year in chronological order.

© parisvas/Thinkstockphotos.com

A total of 208 patients (41.6%) were found to have an incidental cyst, of which less than a quarter were described in the original MRI report, according to a paper published online in Clinical Gastroenterology and Hepatology.

Analysis showed a very strong association between the type of imaging hardware and software, and the presence of cysts; older hardware found pancreatic cysts in 30.3% of patients and the newest hardware found cysts in 56.3% of patients.

However, MRI field strength was not associated with the frequency of lesion discovery (Clin Gastro Hepatol. 2015 Sep 11. doi: 10.1016/j.cgh.2015.08.038).

Most cysts were relatively small, with a median size of 4 mm. Nearly half of the patients with a cyst only had one described.

Nearly two-thirds of these cysts (62%) had an uncertain diagnosis, but 35% of patients were diagnosed with an intraductal papillary mucinous neoplasm, and one patient showed radiologic evidence of subacute pancreatitis.

When compared to the rest of the cohort, individuals with pancreatic cysts were more likely to be older, have diabetes mellitus, or have a personal history of cancer, particularly nonmelanoma skin cancer and hepatocellular carcinoma.

“Our study demonstrates the relationship between the higher trend of incidental pancreatic cysts observed in the recent years and the improvements in the technical features of MRIs,” wrote Dr. Maria Moris and colleagues from the Mayo Clinic, Jacksonville.

The authors said the real prevalence of pancreatic cystic lesions is estimated to range from 0.2% to 44.7%.

Their finding of a prevalence of 41.6% was higher than that found in similar imaging studies, but the authors suggested some of this may be due to the lack of a size cutoff in their study, as opposed to a 5-mm cutoff used in one earlier study that found a prevalence of 10%.

“Moreover, we believe that we may have even underestimated the real prevalence because of the absence of magnetic resonance cholangiopancreatography sequences (only 19% of the examinations), and the lack of 3-T studies (6% of the MRIs),” they wrote.

The median size of the lesions was lower than those found in previous studies.

“This smaller size was unexpected because, as a result of the exclusion criteria applied, the technical features of the MRIs were not the most specific for [pancreatic cystic lesion] PCL visualization,” the authors wrote, suggesting that this may have been due to the radiologist’s experience in this field.

The study was funded by the Joyce E. Baker Foundation for Research at Mayo Clinic in Jacksonville. One author disclosed grants or travel support from Olympus, Boston Scientific, and Cosmo Pharmaceuticals. There were no other conflicts of interest declared.

The apparent increase in the prevalence of incidental pancreatic cysts in recent years may be tied to improvements in MRI scanning technology, results of a study suggest.

Researchers conducted a retrospective analysis of data from 500 patients who underwent an MRI for nonpancreatic indications at a single center between 2005 and 2014; 50 were sampled from each year in chronological order.

© parisvas/Thinkstockphotos.com

A total of 208 patients (41.6%) were found to have an incidental cyst, of which less than a quarter were described in the original MRI report, according to a paper published online in Clinical Gastroenterology and Hepatology.

Analysis showed a very strong association between the type of imaging hardware and software, and the presence of cysts; older hardware found pancreatic cysts in 30.3% of patients and the newest hardware found cysts in 56.3% of patients.

However, MRI field strength was not associated with the frequency of lesion discovery (Clin Gastro Hepatol. 2015 Sep 11. doi: 10.1016/j.cgh.2015.08.038).

Most cysts were relatively small, with a median size of 4 mm. Nearly half of the patients with a cyst only had one described.

Nearly two-thirds of these cysts (62%) had an uncertain diagnosis, but 35% of patients were diagnosed with an intraductal papillary mucinous neoplasm, and one patient showed radiologic evidence of subacute pancreatitis.

When compared to the rest of the cohort, individuals with pancreatic cysts were more likely to be older, have diabetes mellitus, or have a personal history of cancer, particularly nonmelanoma skin cancer and hepatocellular carcinoma.

“Our study demonstrates the relationship between the higher trend of incidental pancreatic cysts observed in the recent years and the improvements in the technical features of MRIs,” wrote Dr. Maria Moris and colleagues from the Mayo Clinic, Jacksonville.

The authors said the real prevalence of pancreatic cystic lesions is estimated to range from 0.2% to 44.7%.

Their finding of a prevalence of 41.6% was higher than that found in similar imaging studies, but the authors suggested some of this may be due to the lack of a size cutoff in their study, as opposed to a 5-mm cutoff used in one earlier study that found a prevalence of 10%.

“Moreover, we believe that we may have even underestimated the real prevalence because of the absence of magnetic resonance cholangiopancreatography sequences (only 19% of the examinations), and the lack of 3-T studies (6% of the MRIs),” they wrote.

The median size of the lesions was lower than those found in previous studies.

“This smaller size was unexpected because, as a result of the exclusion criteria applied, the technical features of the MRIs were not the most specific for [pancreatic cystic lesion] PCL visualization,” the authors wrote, suggesting that this may have been due to the radiologist’s experience in this field.

The study was funded by the Joyce E. Baker Foundation for Research at Mayo Clinic in Jacksonville. One author disclosed grants or travel support from Olympus, Boston Scientific, and Cosmo Pharmaceuticals. There were no other conflicts of interest declared.

The apparent increase in the prevalence of incidental pancreatic cysts in recent years may be tied to improvements in MRI scanning technology, results of a study suggest.

Researchers conducted a retrospective analysis of data from 500 patients who underwent an MRI for nonpancreatic indications at a single center between 2005 and 2014; 50 were sampled from each year in chronological order.

© parisvas/Thinkstockphotos.com

A total of 208 patients (41.6%) were found to have an incidental cyst, of which less than a quarter were described in the original MRI report, according to a paper published online in Clinical Gastroenterology and Hepatology.

Analysis showed a very strong association between the type of imaging hardware and software, and the presence of cysts; older hardware found pancreatic cysts in 30.3% of patients and the newest hardware found cysts in 56.3% of patients.

However, MRI field strength was not associated with the frequency of lesion discovery (Clin Gastro Hepatol. 2015 Sep 11. doi: 10.1016/j.cgh.2015.08.038).

Most cysts were relatively small, with a median size of 4 mm. Nearly half of the patients with a cyst only had one described.

Nearly two-thirds of these cysts (62%) had an uncertain diagnosis, but 35% of patients were diagnosed with an intraductal papillary mucinous neoplasm, and one patient showed radiologic evidence of subacute pancreatitis.

When compared to the rest of the cohort, individuals with pancreatic cysts were more likely to be older, have diabetes mellitus, or have a personal history of cancer, particularly nonmelanoma skin cancer and hepatocellular carcinoma.

“Our study demonstrates the relationship between the higher trend of incidental pancreatic cysts observed in the recent years and the improvements in the technical features of MRIs,” wrote Dr. Maria Moris and colleagues from the Mayo Clinic, Jacksonville.

The authors said the real prevalence of pancreatic cystic lesions is estimated to range from 0.2% to 44.7%.

Their finding of a prevalence of 41.6% was higher than that found in similar imaging studies, but the authors suggested some of this may be due to the lack of a size cutoff in their study, as opposed to a 5-mm cutoff used in one earlier study that found a prevalence of 10%.

“Moreover, we believe that we may have even underestimated the real prevalence because of the absence of magnetic resonance cholangiopancreatography sequences (only 19% of the examinations), and the lack of 3-T studies (6% of the MRIs),” they wrote.

The median size of the lesions was lower than those found in previous studies.

“This smaller size was unexpected because, as a result of the exclusion criteria applied, the technical features of the MRIs were not the most specific for [pancreatic cystic lesion] PCL visualization,” the authors wrote, suggesting that this may have been due to the radiologist’s experience in this field.

The study was funded by the Joyce E. Baker Foundation for Research at Mayo Clinic in Jacksonville. One author disclosed grants or travel support from Olympus, Boston Scientific, and Cosmo Pharmaceuticals. There were no other conflicts of interest declared.

Background

A recent multicenter trial by Smith-Bindman et al¹ showed that ultrasound (point of care [POC] or radiology) should be considered as the first-line imaging test in evaluating patients with suspected renal colic. In addition to its ability to visualize significant renal hydronephrosis, POC ultrasound is also an excellent modality to assess for intrarenal stones.

  

Technique

The study is performed with a curvilinear probe placed in the left and right midaxillary region along the lower costal margin. To obtain a longitudinal view of the kidneys, the probe marker should point toward the head of the bed (Figure 1). The clinician should then slide the probe until the kidney comes into view just caudal to either the liver on the right or the spleen on the left. It is important to remember that the kidneys are retroperitoneal; as such, the probe should be pointed toward the bed to ensure visualization.

The probe should be swept/fanned through the kidney so that the entire organ is visualized from cortex to renal calices. To obtain a transverse view of the kidney, the probe marker should be rotated 90˚ clockwise (Figure 2); the probe should also be swept/fanned through the kidney in this orientation as well. In addition, during evaluation, the bladder should also be scanned in both the longitudinal and transverse planes to assess its volume and the presence of stones.

  

Hydronephrosis

Ureteral or bladder outlet obstruction can lead to unilateral or bilateral renal hydronephrosis, which can present on a spectrum ranging from mild to severe.  As fluid appears black on ultrasound, hydronephrosis will appear black in what is normally an echogenic center of the kidney. The higher the degree of hydronephrosis, the larger the area of black; in cases of severe hydronephrosis, there is thinning of the renal parenchyma and most of the kidney is taken up by dilated calyces (Figure 3). If there is uncertainty during evaluation, color Doppler may be employed to differentiate the vascular renal hilum from hydronephrosis (Figure 4).

  

Ureteral Stones

Ureteral stones are not typically visualized by ultrasound.  However, intrarenal stones can be found. These will appear as hyperechoic structures within the central area of the kidney with acoustic shadowing artifact noted underneath them. Additionally, while scanning the bladder, one can sometimes find a stone lodged in the ureteropelvic junction (UPJ). One can also look for “ureteral jets,” seen as periodic flow of urine within the bladder using color/power Doppler (Figure 5).

  

Pearls/Pitfalls

As abdominal aortic aneurysm (AAA) can mimic renal stones, it is important to scan the aorta in patients presenting with renal colic or flank pain who are at increased risk for AAA or who are older than age 50 years. In addition, during evaluation, the clinician should keep in mind that pregnancy state and aggressive intravenous fluid administration can lead to mild bilateral hydronephrosis. In addition, incidental renal cysts/masses are often encountered during imaging and require close follow-up (Figure 6).

  

  

  

---

Dr Meer is an assistant professor and director of emergency ultrasound, department of emergency medicine, Emory University School of Medicine, Atlanta, Georgia. Dr Beck is an assistant professor, department of emergency medicine, Emory University School of Medicine, Atlanta, Georgia. Dr Taylor is an assistant professor and director of postgraduate medical education, department of emergency medicine, Emory University School of Medicine, Atlanta, Georgia.

Background

A recent multicenter trial by Smith-Bindman et al¹ showed that ultrasound (point of care [POC] or radiology) should be considered as the first-line imaging test in evaluating patients with suspected renal colic. In addition to its ability to visualize significant renal hydronephrosis, POC ultrasound is also an excellent modality to assess for intrarenal stones.

  

Technique

The study is performed with a curvilinear probe placed in the left and right midaxillary region along the lower costal margin. To obtain a longitudinal view of the kidneys, the probe marker should point toward the head of the bed (Figure 1). The clinician should then slide the probe until the kidney comes into view just caudal to either the liver on the right or the spleen on the left. It is important to remember that the kidneys are retroperitoneal; as such, the probe should be pointed toward the bed to ensure visualization.

The probe should be swept/fanned through the kidney so that the entire organ is visualized from cortex to renal calices. To obtain a transverse view of the kidney, the probe marker should be rotated 90˚ clockwise (Figure 2); the probe should also be swept/fanned through the kidney in this orientation as well. In addition, during evaluation, the bladder should also be scanned in both the longitudinal and transverse planes to assess its volume and the presence of stones.

  

Hydronephrosis

Ureteral or bladder outlet obstruction can lead to unilateral or bilateral renal hydronephrosis, which can present on a spectrum ranging from mild to severe.  As fluid appears black on ultrasound, hydronephrosis will appear black in what is normally an echogenic center of the kidney. The higher the degree of hydronephrosis, the larger the area of black; in cases of severe hydronephrosis, there is thinning of the renal parenchyma and most of the kidney is taken up by dilated calyces (Figure 3). If there is uncertainty during evaluation, color Doppler may be employed to differentiate the vascular renal hilum from hydronephrosis (Figure 4).

  

Ureteral Stones

Ureteral stones are not typically visualized by ultrasound.  However, intrarenal stones can be found. These will appear as hyperechoic structures within the central area of the kidney with acoustic shadowing artifact noted underneath them. Additionally, while scanning the bladder, one can sometimes find a stone lodged in the ureteropelvic junction (UPJ). One can also look for “ureteral jets,” seen as periodic flow of urine within the bladder using color/power Doppler (Figure 5).

  

Pearls/Pitfalls

As abdominal aortic aneurysm (AAA) can mimic renal stones, it is important to scan the aorta in patients presenting with renal colic or flank pain who are at increased risk for AAA or who are older than age 50 years. In addition, during evaluation, the clinician should keep in mind that pregnancy state and aggressive intravenous fluid administration can lead to mild bilateral hydronephrosis. In addition, incidental renal cysts/masses are often encountered during imaging and require close follow-up (Figure 6).

  

  

  

---

Dr Meer is an assistant professor and director of emergency ultrasound, department of emergency medicine, Emory University School of Medicine, Atlanta, Georgia. Dr Beck is an assistant professor, department of emergency medicine, Emory University School of Medicine, Atlanta, Georgia. Dr Taylor is an assistant professor and director of postgraduate medical education, department of emergency medicine, Emory University School of Medicine, Atlanta, Georgia.

Background

A recent multicenter trial by Smith-Bindman et al¹ showed that ultrasound (point of care [POC] or radiology) should be considered as the first-line imaging test in evaluating patients with suspected renal colic. In addition to its ability to visualize significant renal hydronephrosis, POC ultrasound is also an excellent modality to assess for intrarenal stones.

  

Technique

The study is performed with a curvilinear probe placed in the left and right midaxillary region along the lower costal margin. To obtain a longitudinal view of the kidneys, the probe marker should point toward the head of the bed (Figure 1). The clinician should then slide the probe until the kidney comes into view just caudal to either the liver on the right or the spleen on the left. It is important to remember that the kidneys are retroperitoneal; as such, the probe should be pointed toward the bed to ensure visualization.

The probe should be swept/fanned through the kidney so that the entire organ is visualized from cortex to renal calices. To obtain a transverse view of the kidney, the probe marker should be rotated 90˚ clockwise (Figure 2); the probe should also be swept/fanned through the kidney in this orientation as well. In addition, during evaluation, the bladder should also be scanned in both the longitudinal and transverse planes to assess its volume and the presence of stones.

  

Hydronephrosis

Ureteral or bladder outlet obstruction can lead to unilateral or bilateral renal hydronephrosis, which can present on a spectrum ranging from mild to severe.  As fluid appears black on ultrasound, hydronephrosis will appear black in what is normally an echogenic center of the kidney. The higher the degree of hydronephrosis, the larger the area of black; in cases of severe hydronephrosis, there is thinning of the renal parenchyma and most of the kidney is taken up by dilated calyces (Figure 3). If there is uncertainty during evaluation, color Doppler may be employed to differentiate the vascular renal hilum from hydronephrosis (Figure 4).

  

Ureteral Stones

Ureteral stones are not typically visualized by ultrasound.  However, intrarenal stones can be found. These will appear as hyperechoic structures within the central area of the kidney with acoustic shadowing artifact noted underneath them. Additionally, while scanning the bladder, one can sometimes find a stone lodged in the ureteropelvic junction (UPJ). One can also look for “ureteral jets,” seen as periodic flow of urine within the bladder using color/power Doppler (Figure 5).

  

Pearls/Pitfalls

As abdominal aortic aneurysm (AAA) can mimic renal stones, it is important to scan the aorta in patients presenting with renal colic or flank pain who are at increased risk for AAA or who are older than age 50 years. In addition, during evaluation, the clinician should keep in mind that pregnancy state and aggressive intravenous fluid administration can lead to mild bilateral hydronephrosis. In addition, incidental renal cysts/masses are often encountered during imaging and require close follow-up (Figure 6).

  

  

  

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Dr Meer is an assistant professor and director of emergency ultrasound, department of emergency medicine, Emory University School of Medicine, Atlanta, Georgia. Dr Beck is an assistant professor, department of emergency medicine, Emory University School of Medicine, Atlanta, Georgia. Dr Taylor is an assistant professor and director of postgraduate medical education, department of emergency medicine, Emory University School of Medicine, Atlanta, Georgia.

Case

A 32-year-old previously healthy woman presented to the ED with right upper arm pain and swelling of 6 days duration. According to the patient, the swelling began 2 days after she sustained a work-related injury at a coin-manufacturing factory. She stated that her right arm had gotten caught inside of a rolling press while she was cleaning it. The roller had stopped over her upper arm, trapping it between the roller and the platform for several minutes before it was extricated. She was brought to the ED by emergency medical services for evaluation immediately following this incident. At this first visit to the ED, the patient complained of mild pain in her right arm. Physical examination at that time revealed mild diffuse swelling extending from her hand to her distal humerus, with mild pain on passive flexion, and extension without associated numbness or tingling. Plain films of her right upper extremity were ordered, the results of which were relatively unremarkable. She was evaluated by an orthopedist, who ruled out compartment syndrome based on her benign physical examination and soft compartments. She was ultimately discharged and told to follow up with her primary care provider.

Over the course of 48 hours from the first ED visit, the patient developed large bullae on the dorsal and volar aspect of her forearm, elbow, and upper arm with associated pain. In addition to dark discolorations of the skin over her affected arm, she noticed that the bullae had become numerous and discolored. These symptoms continued to grow progressively worse, prompting her second presentation to the ED.

With respect to the patient’s history, she denied taking any medications and did not have any significant medical or surgical history. She also denied any new food exposure, infections, or insect bites. Physical examination revealed a young woman who was uncomfortable but cooperative. On inspection, she had multiple hemorrhagic bullae extending circumferentially from the mid-upper arm to her mid-forearm with lightly ecchymotic skin that was more prominent on the medial aspect of her arm (Figure 1). There was notable fluid collection, most prominently in the posterior aspect of her arm underneath the area of greatest skin necrosis. The compartments were flaccid and compressible, and radial, ulnar, and brachial pulses were palpable. The patient complained of diffuse paresthesias and decreased sensation in radial, median, and ulnar nerve distribution. Motor strength of the flexor digitorum superficialis, profundus, extensor policis longus, and extensor carpi radialis remained 5/5.

Laboratory evaluations, which included coagulation studies, were normal with the exception of a minimally elevated creatinine kinase at 239 IU/L (normal, 20-210 IU/L). The patient was evaluated by a trauma surgeon and subsequently underwent ultrasound evaluation (Figure 2) and computed tomography (CT) with intravenous (IV) contrast of the affected arm. Both studies revealed an extensive fluid collection centered in the subcutaneous fat extending from the mid-forearm to the humeral head, consistent with an internal degloving injury.

The patient was taken to the operating room and underwent debridement and resection of the circumferential necrotic skin and subcutaneous tissue in her right arm, and the placement of a skin graft with overlying wound vacuum-assisted closure. During the procedure, a large amount of serosanguinous fluid was drained and cultured, and was found to be sterile. Due to the size of her injury, she underwent two additional episodes of debridement and graft placement over the course of the next 2 weeks.

  

Discussion

First described in the 1850s by the French physician Maurice Morel-Lavallée, Morel-Lavallée lesion is a rare, traumatic, soft-tissue injury.¹ It is an internal degloving injury wherein the skin and subcutaneous tissue have been forcibly separated from the underlying fascia as a result of shear stress. The lymphatic and blood vessels between the layers are also disrupted in this process, resulting in the accumulation of blood and lymphatic fluid as well as subcutaneous debris in the potential space that forms. Excess accumulation over time can compromise blood supply to the overlying skin and cause necrosis.² Morel-Lavallée lesion is missed on initial evaluation in up to one-third of the cases and may have a delay in presentation ranging from hours to months after the inciting injury.³

Morel-Lavallée lesions typically involve the flank, hips, thigh, and prepatellar regions as a result of shear injuries sustained from bicycle falls and motor vehicle accidents.⁴ These lesions are often associated with concomitant acetabular and pelvic fractures.⁵ Involvement of the upper extremities is unusual. Typically, presentation consists of a fluctuant and painful mass underneath the skin which increases over time. The overlying skin may show the mechanism of the original injury, for example, as abrasions after a crush injury. The excessive skin necrosis and hemorrhagic bullae seen in this particular case is a very rare presentation.

 

Differential Diagnosis

The differential diagnosis includes compartment syndrome, coma blisters, a missed fracture, bullous pemphigoid, bullous drug reactions, and linear immunoglobulin A disease. Most of these conditions were easily ruled out in this case as the patient was previously healthy and not on any medications. The lesions in this case could have been confused with coma blisters, which are similar in appearance, self-limiting, and can develop on the extremities. However, coma blisters are classically associated with toxicity from various central nervous system depressants, as well as reduced consciousness from other causes—all of which were readily ruled-out based on the patient’s history. Moreover, the Morel-Lavallée lesion is a degloving injury of the subcutaneous tissue from the fascia underneath, whereas the pathology of coma blisters includes subepidermal bullae formation as well as immunoglobulin and complement deposition.⁶

Diagnostic Imaging

Morel-Lavallée lesion can often be confirmed via several imaging modalities, including  ultrasound, CT, 3D CT, or magnetic resonance imaging (MRI).^3,7 Ultrasound will usually show a well-circumscribed hypoechoic fluid collection with hyperechoic fat globules from the subcutaneous tissue, whereas CT tends to show an encapsulated mass with fluid collection underneath. In MRI, Morel-Lavallée lesion often appears as a hypointense T1-sequence and hyperintense T2-sequence similar to most other fluid collections. There may be variable T1- and T2-intensities with subcutaneous tissues in the fluid collection.²

Management

Despite recognition of this disease entity, controversies still exist regarding management. Case reports have demonstrated a relatively high rate of infected fluid collections depending on the chronicity of the injury.⁸ A recent algorithm to management described by Nickerson et al⁴ proposes that for patients with viable skin, percutaneous aspiration of more than 50 cc of fluid from these lesions should be treated with more extensive operative intervention based on the increased likelihood of recurrence. Patients without viable skin require formal debridement with possible skin grafting.

Other treatment options include conservative management, surgical drainage, sclerodesis, and extensive open surgery.^8-10 Management is always case-based and dependent upon the size of the lesion and associated injuries.

  

Conclusion

This case represents an example of Morel-Lavallée lesions in their most severe and atypical form. It also serves as a reminder that vigilance and knowledge of this disease process is important in helping to diagnose this rare but potentially devastating condition. The key to recognizing this injury lies in keeping this disease process in the differential diagnosis of traumatic injuries with suspicious mechanism involving significant shear forces. Significant physical examination findings may not be present initially and evolve over a time period of hours to days. Once this injury is identified, management hinges on the size of the lesion and affected body part. Despite timely interventions, Morel-Lavallée lesions may result in significant morbidity and functional disability.

  

---

Dr Ye is an emergency medicine resident at the Brown Alpert Medical School in Providence, Rhode Island. Dr Rosenberg is a clinical assistant professor at Brown Alpert Medical School, and an emergency medicine attending physican at Rhode Island Hospital and The Miriam Hospital, Providence, Rhode Island.

Case

A 32-year-old previously healthy woman presented to the ED with right upper arm pain and swelling of 6 days duration. According to the patient, the swelling began 2 days after she sustained a work-related injury at a coin-manufacturing factory. She stated that her right arm had gotten caught inside of a rolling press while she was cleaning it. The roller had stopped over her upper arm, trapping it between the roller and the platform for several minutes before it was extricated. She was brought to the ED by emergency medical services for evaluation immediately following this incident. At this first visit to the ED, the patient complained of mild pain in her right arm. Physical examination at that time revealed mild diffuse swelling extending from her hand to her distal humerus, with mild pain on passive flexion, and extension without associated numbness or tingling. Plain films of her right upper extremity were ordered, the results of which were relatively unremarkable. She was evaluated by an orthopedist, who ruled out compartment syndrome based on her benign physical examination and soft compartments. She was ultimately discharged and told to follow up with her primary care provider.

Over the course of 48 hours from the first ED visit, the patient developed large bullae on the dorsal and volar aspect of her forearm, elbow, and upper arm with associated pain. In addition to dark discolorations of the skin over her affected arm, she noticed that the bullae had become numerous and discolored. These symptoms continued to grow progressively worse, prompting her second presentation to the ED.

With respect to the patient’s history, she denied taking any medications and did not have any significant medical or surgical history. She also denied any new food exposure, infections, or insect bites. Physical examination revealed a young woman who was uncomfortable but cooperative. On inspection, she had multiple hemorrhagic bullae extending circumferentially from the mid-upper arm to her mid-forearm with lightly ecchymotic skin that was more prominent on the medial aspect of her arm (Figure 1). There was notable fluid collection, most prominently in the posterior aspect of her arm underneath the area of greatest skin necrosis. The compartments were flaccid and compressible, and radial, ulnar, and brachial pulses were palpable. The patient complained of diffuse paresthesias and decreased sensation in radial, median, and ulnar nerve distribution. Motor strength of the flexor digitorum superficialis, profundus, extensor policis longus, and extensor carpi radialis remained 5/5.

Laboratory evaluations, which included coagulation studies, were normal with the exception of a minimally elevated creatinine kinase at 239 IU/L (normal, 20-210 IU/L). The patient was evaluated by a trauma surgeon and subsequently underwent ultrasound evaluation (Figure 2) and computed tomography (CT) with intravenous (IV) contrast of the affected arm. Both studies revealed an extensive fluid collection centered in the subcutaneous fat extending from the mid-forearm to the humeral head, consistent with an internal degloving injury.

The patient was taken to the operating room and underwent debridement and resection of the circumferential necrotic skin and subcutaneous tissue in her right arm, and the placement of a skin graft with overlying wound vacuum-assisted closure. During the procedure, a large amount of serosanguinous fluid was drained and cultured, and was found to be sterile. Due to the size of her injury, she underwent two additional episodes of debridement and graft placement over the course of the next 2 weeks.

  

Discussion

First described in the 1850s by the French physician Maurice Morel-Lavallée, Morel-Lavallée lesion is a rare, traumatic, soft-tissue injury.¹ It is an internal degloving injury wherein the skin and subcutaneous tissue have been forcibly separated from the underlying fascia as a result of shear stress. The lymphatic and blood vessels between the layers are also disrupted in this process, resulting in the accumulation of blood and lymphatic fluid as well as subcutaneous debris in the potential space that forms. Excess accumulation over time can compromise blood supply to the overlying skin and cause necrosis.² Morel-Lavallée lesion is missed on initial evaluation in up to one-third of the cases and may have a delay in presentation ranging from hours to months after the inciting injury.³

Morel-Lavallée lesions typically involve the flank, hips, thigh, and prepatellar regions as a result of shear injuries sustained from bicycle falls and motor vehicle accidents.⁴ These lesions are often associated with concomitant acetabular and pelvic fractures.⁵ Involvement of the upper extremities is unusual. Typically, presentation consists of a fluctuant and painful mass underneath the skin which increases over time. The overlying skin may show the mechanism of the original injury, for example, as abrasions after a crush injury. The excessive skin necrosis and hemorrhagic bullae seen in this particular case is a very rare presentation.

 

Differential Diagnosis

The differential diagnosis includes compartment syndrome, coma blisters, a missed fracture, bullous pemphigoid, bullous drug reactions, and linear immunoglobulin A disease. Most of these conditions were easily ruled out in this case as the patient was previously healthy and not on any medications. The lesions in this case could have been confused with coma blisters, which are similar in appearance, self-limiting, and can develop on the extremities. However, coma blisters are classically associated with toxicity from various central nervous system depressants, as well as reduced consciousness from other causes—all of which were readily ruled-out based on the patient’s history. Moreover, the Morel-Lavallée lesion is a degloving injury of the subcutaneous tissue from the fascia underneath, whereas the pathology of coma blisters includes subepidermal bullae formation as well as immunoglobulin and complement deposition.⁶

Diagnostic Imaging

Morel-Lavallée lesion can often be confirmed via several imaging modalities, including  ultrasound, CT, 3D CT, or magnetic resonance imaging (MRI).^3,7 Ultrasound will usually show a well-circumscribed hypoechoic fluid collection with hyperechoic fat globules from the subcutaneous tissue, whereas CT tends to show an encapsulated mass with fluid collection underneath. In MRI, Morel-Lavallée lesion often appears as a hypointense T1-sequence and hyperintense T2-sequence similar to most other fluid collections. There may be variable T1- and T2-intensities with subcutaneous tissues in the fluid collection.²

Management

Despite recognition of this disease entity, controversies still exist regarding management. Case reports have demonstrated a relatively high rate of infected fluid collections depending on the chronicity of the injury.⁸ A recent algorithm to management described by Nickerson et al⁴ proposes that for patients with viable skin, percutaneous aspiration of more than 50 cc of fluid from these lesions should be treated with more extensive operative intervention based on the increased likelihood of recurrence. Patients without viable skin require formal debridement with possible skin grafting.

Other treatment options include conservative management, surgical drainage, sclerodesis, and extensive open surgery.^8-10 Management is always case-based and dependent upon the size of the lesion and associated injuries.

  

Conclusion

This case represents an example of Morel-Lavallée lesions in their most severe and atypical form. It also serves as a reminder that vigilance and knowledge of this disease process is important in helping to diagnose this rare but potentially devastating condition. The key to recognizing this injury lies in keeping this disease process in the differential diagnosis of traumatic injuries with suspicious mechanism involving significant shear forces. Significant physical examination findings may not be present initially and evolve over a time period of hours to days. Once this injury is identified, management hinges on the size of the lesion and affected body part. Despite timely interventions, Morel-Lavallée lesions may result in significant morbidity and functional disability.

  

---

Dr Ye is an emergency medicine resident at the Brown Alpert Medical School in Providence, Rhode Island. Dr Rosenberg is a clinical assistant professor at Brown Alpert Medical School, and an emergency medicine attending physican at Rhode Island Hospital and The Miriam Hospital, Providence, Rhode Island.

Case

A 32-year-old previously healthy woman presented to the ED with right upper arm pain and swelling of 6 days duration. According to the patient, the swelling began 2 days after she sustained a work-related injury at a coin-manufacturing factory. She stated that her right arm had gotten caught inside of a rolling press while she was cleaning it. The roller had stopped over her upper arm, trapping it between the roller and the platform for several minutes before it was extricated. She was brought to the ED by emergency medical services for evaluation immediately following this incident. At this first visit to the ED, the patient complained of mild pain in her right arm. Physical examination at that time revealed mild diffuse swelling extending from her hand to her distal humerus, with mild pain on passive flexion, and extension without associated numbness or tingling. Plain films of her right upper extremity were ordered, the results of which were relatively unremarkable. She was evaluated by an orthopedist, who ruled out compartment syndrome based on her benign physical examination and soft compartments. She was ultimately discharged and told to follow up with her primary care provider.

Over the course of 48 hours from the first ED visit, the patient developed large bullae on the dorsal and volar aspect of her forearm, elbow, and upper arm with associated pain. In addition to dark discolorations of the skin over her affected arm, she noticed that the bullae had become numerous and discolored. These symptoms continued to grow progressively worse, prompting her second presentation to the ED.

With respect to the patient’s history, she denied taking any medications and did not have any significant medical or surgical history. She also denied any new food exposure, infections, or insect bites. Physical examination revealed a young woman who was uncomfortable but cooperative. On inspection, she had multiple hemorrhagic bullae extending circumferentially from the mid-upper arm to her mid-forearm with lightly ecchymotic skin that was more prominent on the medial aspect of her arm (Figure 1). There was notable fluid collection, most prominently in the posterior aspect of her arm underneath the area of greatest skin necrosis. The compartments were flaccid and compressible, and radial, ulnar, and brachial pulses were palpable. The patient complained of diffuse paresthesias and decreased sensation in radial, median, and ulnar nerve distribution. Motor strength of the flexor digitorum superficialis, profundus, extensor policis longus, and extensor carpi radialis remained 5/5.

Laboratory evaluations, which included coagulation studies, were normal with the exception of a minimally elevated creatinine kinase at 239 IU/L (normal, 20-210 IU/L). The patient was evaluated by a trauma surgeon and subsequently underwent ultrasound evaluation (Figure 2) and computed tomography (CT) with intravenous (IV) contrast of the affected arm. Both studies revealed an extensive fluid collection centered in the subcutaneous fat extending from the mid-forearm to the humeral head, consistent with an internal degloving injury.

The patient was taken to the operating room and underwent debridement and resection of the circumferential necrotic skin and subcutaneous tissue in her right arm, and the placement of a skin graft with overlying wound vacuum-assisted closure. During the procedure, a large amount of serosanguinous fluid was drained and cultured, and was found to be sterile. Due to the size of her injury, she underwent two additional episodes of debridement and graft placement over the course of the next 2 weeks.

  

Discussion

First described in the 1850s by the French physician Maurice Morel-Lavallée, Morel-Lavallée lesion is a rare, traumatic, soft-tissue injury.¹ It is an internal degloving injury wherein the skin and subcutaneous tissue have been forcibly separated from the underlying fascia as a result of shear stress. The lymphatic and blood vessels between the layers are also disrupted in this process, resulting in the accumulation of blood and lymphatic fluid as well as subcutaneous debris in the potential space that forms. Excess accumulation over time can compromise blood supply to the overlying skin and cause necrosis.² Morel-Lavallée lesion is missed on initial evaluation in up to one-third of the cases and may have a delay in presentation ranging from hours to months after the inciting injury.³

Morel-Lavallée lesions typically involve the flank, hips, thigh, and prepatellar regions as a result of shear injuries sustained from bicycle falls and motor vehicle accidents.⁴ These lesions are often associated with concomitant acetabular and pelvic fractures.⁵ Involvement of the upper extremities is unusual. Typically, presentation consists of a fluctuant and painful mass underneath the skin which increases over time. The overlying skin may show the mechanism of the original injury, for example, as abrasions after a crush injury. The excessive skin necrosis and hemorrhagic bullae seen in this particular case is a very rare presentation.

 

Differential Diagnosis

The differential diagnosis includes compartment syndrome, coma blisters, a missed fracture, bullous pemphigoid, bullous drug reactions, and linear immunoglobulin A disease. Most of these conditions were easily ruled out in this case as the patient was previously healthy and not on any medications. The lesions in this case could have been confused with coma blisters, which are similar in appearance, self-limiting, and can develop on the extremities. However, coma blisters are classically associated with toxicity from various central nervous system depressants, as well as reduced consciousness from other causes—all of which were readily ruled-out based on the patient’s history. Moreover, the Morel-Lavallée lesion is a degloving injury of the subcutaneous tissue from the fascia underneath, whereas the pathology of coma blisters includes subepidermal bullae formation as well as immunoglobulin and complement deposition.⁶

Diagnostic Imaging

Morel-Lavallée lesion can often be confirmed via several imaging modalities, including  ultrasound, CT, 3D CT, or magnetic resonance imaging (MRI).^3,7 Ultrasound will usually show a well-circumscribed hypoechoic fluid collection with hyperechoic fat globules from the subcutaneous tissue, whereas CT tends to show an encapsulated mass with fluid collection underneath. In MRI, Morel-Lavallée lesion often appears as a hypointense T1-sequence and hyperintense T2-sequence similar to most other fluid collections. There may be variable T1- and T2-intensities with subcutaneous tissues in the fluid collection.²

Management

Despite recognition of this disease entity, controversies still exist regarding management. Case reports have demonstrated a relatively high rate of infected fluid collections depending on the chronicity of the injury.⁸ A recent algorithm to management described by Nickerson et al⁴ proposes that for patients with viable skin, percutaneous aspiration of more than 50 cc of fluid from these lesions should be treated with more extensive operative intervention based on the increased likelihood of recurrence. Patients without viable skin require formal debridement with possible skin grafting.

Other treatment options include conservative management, surgical drainage, sclerodesis, and extensive open surgery.^8-10 Management is always case-based and dependent upon the size of the lesion and associated injuries.

  

Conclusion

This case represents an example of Morel-Lavallée lesions in their most severe and atypical form. It also serves as a reminder that vigilance and knowledge of this disease process is important in helping to diagnose this rare but potentially devastating condition. The key to recognizing this injury lies in keeping this disease process in the differential diagnosis of traumatic injuries with suspicious mechanism involving significant shear forces. Significant physical examination findings may not be present initially and evolve over a time period of hours to days. Once this injury is identified, management hinges on the size of the lesion and affected body part. Despite timely interventions, Morel-Lavallée lesions may result in significant morbidity and functional disability.

  

---

Dr Ye is an emergency medicine resident at the Brown Alpert Medical School in Providence, Rhode Island. Dr Rosenberg is a clinical assistant professor at Brown Alpert Medical School, and an emergency medicine attending physican at Rhode Island Hospital and The Miriam Hospital, Providence, Rhode Island.