Malignant basomelanocytic tumor manifesting as metastatic melanoma.

We report a case of an unusual basomelanocytic tumor from the scalp of a 56-year-old man. A 56-year-old white man presented with a scalp lesion that was biopsied and interpreted as a basal cell carcinoma. Fourteen months later, metastatic melanoma was discovered in a cervical lymph node and the liver. A subsequent biopsy from the area of the previously biopsied basal cell carcinoma of the scalp showed an invasive malignant melanoma. Immunohistochemical stains performed on the original scalp specimen showed biphasic immunohistochemical profile. A population of neoplastic cells was strongly positive for the melanocytic markers Melan-A, HMB-45, and tyrosinase and showed weak focal immunoreactivity for S-100. A second population of cells was strongly immunoreactive for keratin (wide-spectrum polyclonal antibody) and BerEp4. To our knowledge, this is the first description of a malignant basomelanocytic tumor complicated by metastatic melanoma.