Rhabdomyoblastic differentiation in malignant melanoma in adults: report of 2 cases.

Two cases of malignant melanoma are reported in adults exhibiting rhabdomyoblastic differentiation to alert pathologists to this rare variant of malignant melanoma. One of the cases presented as a metastasis in a submandibular lymph node, and the other was a primary skin melanoma. There are only a few published reports on melanocytic tumors with rhabdomyoblastic differentiation, mainly occurring in giant congenital nevi. Both cases reported here were confirmed by immunohistochemistry. Both cases were also studied by electron microscopy, and one showed distinctive ultrastructural features of striated muscle.