Myoepithelioma with melanocytic colonization (melanocytic myoepithelioma): a case report

Mixed tumors of the salivary glands and the skin (also known as chondroid syringomas) contain epithelial and myoepithelial components in a chondroid to myxoid stroma. Lesions that are composed solely of cells with myoepithelial differentiation are known as myoepitheliomas. These tumors have been well described in the salivary glands and many other sites, and within the past decade, cutaneous myoepitheliomas have been described as well. Immunohistochemically, these lesions are typically positive for S-100, cytokeratin and/or epithelial membrane antigen (EMA), with variable positivity for glial fibrillary acid protein and myogenic markers such as actin and calponin. Rare case reports have described the presence of melanocytes in mixed tumors of the salivary glands, but they have not been shown in mixed tumors or myoepitheliomas of the skin. We report a case of a cutaneous myoepithelioma with a distinct subpopulation of spindled to dendritic melanocytes, confirmed by immunohistochemical positivity for S-100, HMB-45 and melanoma antigen recognized by T-cells-1 (Mart-1).