Fibrolipomatous hamartoma of the median nerve

Case contributed by Dr Andrew Lawson


Swollen forearm

Patient Data

Age: 50
Gender: Male

There is an extensive fibrolipomatous hamartoma of the median nerve.  The nerve is grossly thickened with lipomatous tissue interdigitating between prominent fassicles with a 'coaxial cable'-like appearance. This abnormality extends throughout the entire imaging field of view from the level of the elbow articulation to the decussation of the median nerve distal to the carpal tunnel. The abnormality extends into the digital nerves of all the fingers. The nerve has a maximal diameter in the carpal tunnel with gross bowing and convexity of the overlying carpal tunnel retinacula sheath.

Small poorly encapsulated subcutaneous lipomatous lesions are noted in the palmar soft tissues at the level of the mid and distal carpal rows. One of these foci is adjacent to the flexor carpis radialis tendon. These areas demonstrate homogeneous suppression on the STIR sequence.  There is linear scar tissue volar to the trapezium at this level related to previous surgical excision with mild STIR hyperintensity but there is no discrete non-adipose mass to suggest a liposarcoma. There is overlying thickening of the dermis at the level of the carpal tunnel extending into the palm.  

There is macrodystrophy of the thumb and index finger with osseous and fibrofatty soft tissue hypertrophy. No focal soft tissue mass is identified at these sites. There is marked associated cutaneous thickening. There is no significant focal osseous lesion of the forearm, carpus or hand.


The findings are consistent with an extensive fibrolipomatous hamartoma throughout the imaged median nerve with severe mass effect in the carpal tunnel, which would account for the neurological symptoms. There is associated macrodactyly of the index finger and thumb. There are superficial fibrofatty mass lesions at the volar aspect of the wrist with adjacent post surgical change.

Clinical appearance of this patient.

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Case information

rID: 28312
Published: 20th Mar 2014
Last edited: 1st Oct 2015
Inclusion in quiz mode: Included

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