Five cases of fibrolipomatous hamartoma are described. The median nerve was involved in four cases, the medial plantar nerve in one case. In the two cases with involvement of the median nerve in the wrist, the diagnosis was macroscopically suspected on the typical fusiform, segmentary enlargement of the nerve by fibrolipomatous tissue. Histologically, the epineurium was expanded by fibrolipomatous tissue and the scattered nerve bundles were dissociated by perineurial and endoneurial fibrosis. At ultrastructural examination the nerve bundles were constituted of "onion bulblike formations" with one or two central nerve fibers and peripheral perineurial cells. Eighty-eight cases of fibrolipomatous hamartoma were published in the medical literature, thirty-six with macrodactyly. This rare and probably congenital affection frequently involve the median nerve (78%).

Fibrolipomatous hamartoma of the median nerve. J Hand Surg [Br]. 1987 Jun;12(2):224-6

A case of fibrolipomatous hamartoma of the median nerve is presented. The operative findings were characteristic. The diagnosis should be confirmed by histological examination of a biopsy from an involved palmar cutaneous branch, and treatment should be limited to decompression of the ligament or fascia over the involved area.

MR imaging of uncommon recurrence of fibrolipomatous hamartoma of the ulnar nerve.Acta Radiol. 2003 May;44(3):326-8.

We present the MR and histopathologic findings of fibrolipomatous hamartoma (FLH) of the ulnar nerve in a 54-year-old woman, a lipomatous process that rarely affects the ulnar nerve. The case illustrated is further unusual as a local soft tissue recurrent mass developed over a remarkably long course of the disease.