Adenomyoepithelioma of the skin: a case report with immunohistochemical and ultrastructural observations.
The histological, immunohistochemical and electron microscopic features of a primary adenomyoepithelioma of skin, a rare sweat gland tumour, are reported. The tumour occurred on the back of a 92-year-old woman. It was composed of well-formed tubules lined by epithelial cells surrounded by clear or spindled myoepithelial cells. Immunohistochemically, the epithelial cells exhibited strong cytokeratin (CAM5.2) and weak carcinoembryonic antigen positivity. The myoepithelial cells showed diffuse positivity for smooth muscle actin and focal positivity for S100 protein. Ultrastructurally, the myoepithelial cells contained myofilaments with focal densities and hemidesmosomes. They were limited by well-formed basal lamina. The tumour was associated with a small eccrine spiradenoma. We predict that the tumour will behave in a benign fashion. There is no evidence of recurrence or metastasis 28 months later.