Angiomatoid melanoma: A novel pattern of differentiation in invasive periocular desmoplastic malignant melanoma

A case of locally invasive, long standing desmoplastic and amelanotic malig nant melanoma is described in an 84-year-old man. Histologic examination of the involved periorbital tissue showed neoplastic foci exhibiting a novel pattern reminiscent of microvascular proliferation. These regions were char acterized by malignant, S-100-positive tumor cells lining vessel-like space s in transverse sections and forming tubuler-like structures in longitudina l sections. Recent data indicate that melanoma cells may express genes and patterns of differentiation in vitro akin to endothelial cells. Because ang iosarcoma often involves facial and scalp skin of elderly individuals, awar eness of angiomatoid differentiation in melanoma has important diagnostic i mplications. Copyright (C) 2000 by W.B. Saunders Company.