Electron microscopy in the evaluation of melanocytic tumors

Melanoma is the "syphilis of malignant tumors", said one of my favorite mentors (Dr Jerome Wollman, Wadsworth VA Hospital, Los Angeles, California). What syphilis is to clinicians, melanoma is to surgical pathologists. By light microscopy, melanoma, especially in its metastatic form, can exhibit any imaginable pattern, can be amelanotic, and the immunostaining can be negative or equivocal. The present review deals with the features of both classic and aberrant forms of melanosomes. In addition to melanosome morphology, spectrum of ultrastructural features of usual and unusual histological variants of melanoma are described and illustrated. Finally, the role of immunoelectron microscopy is discussed briefly.