대한근골격영상의학회

Title : Case 69

Age / Sex : / Age / Sex : 17 /F Chief complaint : A soft, slowly enlarging mass in the volar aspect of left hand. The mass was noted in early childhood 1) What is your impression? Two weeks later, you can see the final diagnosis with a brief discussion of this case. * Send Application Answers to Ja-Young Choi, MD (drchoi01@radiol.snu.ac.kr) Courtesy : Juhng Seon-Kwan, MD. Wonkwang University School of Medicine and Hospital Diagnosis: Lipomatosis of nerve Discussion Findings: T1WI show multiple, cord like longitudinally oriented cylindrical low signal intensities surrounded by increased signal intensities along the course of median nerve and its digital branches. Cable like structures was enhanced and background high signal intensity was well suppressed on fat suppressed T1WI with contrast enhancement. Discussion: Lipomatosis of nerve was initially described in 1953 by Mason and has been referred to in the past by various terms, including fibrolipomatous hamartoma of nerve, perineural lipoma, fatty infiltration of the nerve, intraneural lipoma, and neural fibrolipoma. In 2002, the WHO adopted the designation of lipomatosis of nerve. There is no known cause or hereditary predisposition for this lesion, although hypertrophy of mature fat and fibroblasts in the epineurium has been postulated. Patients typically present before the age of 30 years and most commonly at birth or early childhood. The upper extremity is affected in 78%–96% of cases, particularly the median nerve (85% of cases). The most frequent clinical manifestation is a slowly growing mass at the wrist, hand, or forearm. The ulnar nerve is the second most commonly affected site. The lower extremity is involved in 4%–22% of patients, with other reported cases affecting the radial nerve, brachial plexus, and cranial nerves. Pain and neurologic symptoms including carpal tunnel syndrome may be associated with lipomatosis of nerve. At gross pathologic examination, the affected nerve is diffusely enlarged by yellow fibrofatty tissue. Histologic evaluation reveals that the fatty infiltration separates individual nerve bundles. This infiltrative pattern allows distinction from a soft-tissue lipoma that lies adjacent to nerve. The nerve fibers are usually intrinsically normal, although atrophy has been reported late in the disease. The pathologic appearance is the same, regardless of the presence or absence of macrodactyly. Macrodactyly results in disproportionate fibroadipose tissue overgrowth in the affected digits. Radiographs of patients without associated macrodactyly often appear normal, although a soft-tissue mass may be seen. Macrodactyly causes soft-tissue and osseous overgrowth, both longitudinally and axially. Bone overgrowth is typically more prominent volarly and distally, often resulting in osseous bowing. The osseous overgrowth usually does not progress after puberty. The bone deformity may lead to premature osteoarthritis. Soft-tissue overgrowth often appears as increased radiolucent tissue that corresponds to fat. The imaging appearance, particularly with sonography and MR imaging, of advanced lipomatosis of nerve is usually pathognomonic and reflects the underlying disease. Sonography reveals alternating hyperechoic (fat) and hypoechoic (nerve fascicles) bands in a diffusely enlarged nerve, thus creating a cablelike appearance. The MR imaging appearance is similar, with longitudinally oriented cylindrical areas of low to intermediate signal intensity (nerve fascicles) surrounded by adipose tissue in a diffusely thickened nerve. Increased fat content in the digits is also apparent in patients with macrodactyly on MR images. References: Murphey MD, Carroll JF, Flemming DJ, Pope TL, Gannon FH, Kransdorf MJ. Benign Musculoskeletal Lipomatous Lesions RadioGraphics 2004;24:1433-1466

Title : Case 69

Age / Sex : /

Age / Sex : 17 /F
Chief complaint : A soft, slowly enlarging mass in the volar aspect of left hand. The mass was noted in early childhood

1) What is your impression?

Two weeks later, you can see the final diagnosis with a brief discussion of this case.

* Send Application Answers to Ja-Young Choi, MD (drchoi01@radiol.snu.ac.kr)

Courtesy : Juhng Seon-Kwan, MD. Wonkwang University School of Medicine and Hospital

Diagnosis:

Lipomatosis of nerve

Discussion

Findings:
T1WI show multiple, cord like longitudinally oriented cylindrical low signal intensities surrounded by increased signal intensities along the course of median nerve and its digital branches. Cable like structures was enhanced and background high signal intensity was well suppressed on fat suppressed T1WI with contrast enhancement.

Discussion:
Lipomatosis of nerve was initially described in 1953 by Mason and has been referred to in the past by various terms, including fibrolipomatous hamartoma of nerve, perineural lipoma, fatty infiltration of the nerve, intraneural lipoma, and neural fibrolipoma. In 2002, the WHO adopted the designation of lipomatosis of nerve. There is no known cause or hereditary predisposition for this lesion, although hypertrophy of mature fat and fibroblasts in the epineurium has been postulated. Patients typically present before the age of 30 years and most commonly at birth or early childhood. The upper extremity is affected in 78%–96% of cases, particularly the median nerve (85% of cases). The most frequent clinical manifestation is a slowly growing mass at the wrist, hand, or forearm. The ulnar nerve is the second most commonly affected site. The lower extremity is involved in 4%–22% of patients, with other reported cases affecting the radial nerve, brachial plexus, and cranial nerves. Pain and neurologic symptoms including carpal tunnel syndrome may be associated with lipomatosis of nerve. At gross pathologic examination, the affected nerve is diffusely enlarged by yellow fibrofatty tissue. Histologic evaluation reveals that the fatty infiltration separates individual nerve bundles. This infiltrative pattern allows distinction from a soft-tissue lipoma that lies adjacent to nerve. The nerve fibers are usually intrinsically normal, although atrophy has been reported late in the disease. The pathologic appearance is the same, regardless of the presence or absence of macrodactyly. Macrodactyly results in disproportionate fibroadipose tissue overgrowth in the affected digits. Radiographs of patients without associated macrodactyly often appear normal, although a soft-tissue mass may be seen. Macrodactyly causes soft-tissue and osseous overgrowth, both longitudinally and axially. Bone overgrowth is typically more prominent volarly and distally, often resulting in osseous bowing. The osseous overgrowth usually does not progress after puberty. The bone deformity may lead to premature osteoarthritis. Soft-tissue overgrowth often appears as increased radiolucent tissue that corresponds to fat. The imaging appearance, particularly with sonography and MR imaging, of advanced lipomatosis of nerve is usually pathognomonic and reflects the underlying disease. Sonography reveals alternating hyperechoic (fat) and hypoechoic (nerve fascicles) bands in a diffusely enlarged nerve, thus creating a cablelike appearance. The MR imaging appearance is similar, with longitudinally oriented cylindrical areas of low to intermediate signal intensity (nerve fascicles) surrounded by adipose tissue in a diffusely thickened nerve. Increased fat content in the digits is also apparent in patients with macrodactyly on MR images.

References:
Murphey MD, Carroll JF, Flemming DJ, Pope TL, Gannon FH, Kransdorf MJ. Benign Musculoskeletal Lipomatous Lesions RadioGraphics 2004;24:1433-1466

Correct Answer
Name	Institution
이경규: 한강성심병원
주승호: 건강보험공단 일산 병원
우성구: 부산대학병원 전공의
안영이: 여의도성모병원 전공의
장진희: 가톨릭중앙의료원 전공의
박혜정: 가톨릭중앙의료원 전공의
김정현: 가톨릭중앙의료원 전공의
김완태: 서울보훈병원
김권형: 제주한마음병원
김미영: 가톨릭중앙의료원 전공의
박소영: 분당서울대병원
최희석: 동국대학교 일산 병원
박상현: 순천향대학천안병원
하종수: 광명성애병원