Melanoma with rhabdomyosarcomatous differentiation.

Melanoma with rhabdomyosarcomatous differentiation is an extremely rare observation with a review of the literature revealing fewer than 15 previously identified cases. The authors describe a case of a 72-year-old man with a cutaneous lesion of the left scalp that was diagnosed as malignant melanoma on biopsy and wide excision. One month later, a punch biopsy of the excisional area revealed rhabdomyosarcomatous proliferation. Re-examination of the wide-excision specimen with muscle markers revealed areas of neoplastic melanoma cells consistent with rhabdomyosarcomatous differentiation.