Two cases of mélanose neurocutanée with development of malignant melanoma: a microspectrophotometric and electron microscopic study.

Two cases of neurocutaneous melanosis with development of malignant melanoma in the Japanese are presented. The first case was a 4-year-old boy in whom a retroperitoneal melanoma appeared with giant nevi, and cerebral and spinal melanosis. The second case was a 39-year-old man, in whom a primary leptomeningeal melanoma developed with leptomeningeal melanosis and smaller pigmented nevi. Microspectrophotometric and electron microscopic studies were made on the neoplastic and non-neoplastic melanotic tissues to elucidate the histogenesis of this rare disorder. Two different patterns of nuclear DNA histograms, corresponding to melanosis and melanoma, were obtained by microspectrophotometry, Considerable variation in the ultrastructure of the melanocytes was seen by electron microscopy.