Epithelioid melanoma cells (400×, H&E). These cells resemble epithelium because of abundant eosinophilic cytoplasm and enlarged round to oval-shaped nuclei. Epithelioid melanoma cells often lack cohesiveness and demonstrate marked pleomorphism, including the formation of multinucleated tumor cells (arrow). Nuclei have a conspicuous nuclear membrane, very coarse chromatin, and large nucleoli. Note the balloon cells (arrowheads).