Rudimentary polydactyly (cutaneous neuroma) case report with ultrastructural study.

A case of rudimentary polydactyly (cutaneous neuroma) on the ulnar aspect of the left fifth finger of a 38-year-old male was examined and the skin was studied by light and electron microscopy. In addition to a proliferation of nerve fibers and encapsulated corpuscles, normal Merkel cells were often present in the basal portion of the epidermis. It is suggested that proliferation of various neural components is the essential feature of the affected skin.