Age / Sex : 20 / F

Chief complaint: palpable mass

What is your impression?

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

(Please submit only one answer)

Courtesy: Sang Hoon Lee, Asan Medical Center, Ulsan University College of medicine

Lipomatosis of nerve (fibrolipomatous hamartoma)

Discussion

Findings:

X-ray: Soft tissue swelling of great toe.

MRI: Mixed high and low signal intensity mass lesion at the subcutaneous layer, inferomedial aspect, great toe and 1^st metatarsal bone level. The tumor margin was hardly differentiated with normal subcutaneous fat. Enlarged fascicular appearance of plantar digital nerve.

Differential Diagnosis:

Macrodystrophia lipomatosa: combined bone hypertrophy

Neurofibromatosis: multifocal involvement

Diagnosis:  

Lipomatosis of nerve

Discussion:

Histology

Anomalous growth of fibroadipose tissue of nerve sheath

Thickened nerve bundles(a)

Endoneural, perineural fibrosis(b)

Increased fatty tissue(c)

Onset: before 30, m/c - at birth or early childhood

Incidence: rare

Upper extremity: 78~96%

median nerve(m/c, 85%)

Lower extremity: 4~22%

Foot: 10 case

5 case: medial plantar nerve

3 case: superficial peroneal nerve

2 case: not specified

MR

unique and characteristic

serpentine low-intensity structures

thickened nerve fascicles

surrounded by evenly distributed fat

short axis: coaxial-cable-like appearance

long axis: spaghetti-like appearance

imaging spectrum reflecting amount of fat and fibrous tissue in mass

References:

1. Fibrolipomatous hamartoma in the foot: atypical MR imaging findings. Van Breuseghem I, Sciot R, Pans S, Geusens E, Brys P, De Wever I. Skeletal Radiol. 2003 Nov;32(11):651-5.


2. From the archives of the AFIP: benign musculoskeletal lipomatous lesions. Murphey MD, Carroll JF, Flemming DJ, Pope TL, Gannon FH, Kransdorf MJ. Radiographics. 2004 Sep-Oct;24(5):1433-66. Review.


3. Lipofibromatous hamartoma of the upper extremity: a review of the radiologic findings for 15 patients. Toms AP, Anastakis D, Bleakney RR, Marshall TJ. AJR Am J Roentgenol. 2006 Mar;186(3):805-11.