Lipomatosis of the Median Nerve: A Case Report

Lipomatosis of nerve is a rare, nonhereditary congenital overgrowth disorder involving fibroadipose tissue proliferation along nerve territories, most commonly the median and plantar nerves. We report a case of a 35-year-old man presenting with slowly progressive enlargement of the thumb and index finger since childhood, associated with increasing discomfort. Imaging demonstrated nonencapsulated fatty overgrowth with digital nerve involvement and associated bony hypertrophy. Surgical management included right thumb debulking and distal phalanx amputation of the index finger. Histopathologic examination confirmed infiltration of epineural and perineurial structures by adipose and fibrous tissue, consistent with lipomatosis of the median nerve. Postoperatively, the patient exhibited diminished thumb sensation with a preserved range of motion. This case highlights the diagnostic role of imaging, along with radiologic-pathologic correlation and the potential for postoperative sensory loss because of unavoidable excision of involved nerve tissue.