Nodal and subcutaneous cellular blue nevi. A pseudometastasizing pseudomelanoma.

A 20-year-old white woman had extensive surgery for "metastatic melanoma" of the dorsum of the right foot and surgical removal of two regional inguinal lymph nodes. Review of the histopathological sections ten years later revealed all three lesions to be cellular blue nevi. Cellular blue nevi may resemble melanoma histologically and, relative to their incidence, are quite frequently found in lymph nodes. Thus they may present a uniquely challenging differential diagnosis with metastatic melanoma.