[Fibrolipomatous hamartoma of the peripheral nerves. Anatomico-clinical study of 5 cases, including 2 with ultrastructural study].

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%).