Blue Nevus Versus Pigmented Epithelioid Melanocytoma

Blue nevi (dermal melanocytomas) and their variants are characterized by melanocytes containing abundant cytoplasmic melanin. These lesions must be distinguished from heavily pigmented melanomas. Pigmented epithelioid melanocytoma (PEM) is a recently described melanocytic tumor with histologic features overlapping blue nevus and melanoma and having a less aggressive clinical course. This chapter highlights the features that help to distinguish these histologically similar lesions. The discussion is expanded to include other lesions (neoplastic and inflammatory) containing abundant melanin and other pigmented material resembling melanin.