Mixed tumors of the skin of the salivary gland type: a light and electron microscopic study.

The light and electron microscopic features of two mixed tumors of the skin of the salivary gland type demonstrate eccrine differentiation of the epithelial component. The tumors were made up of tuboalveolar spaces lined by an eccrine duct type of epithelium with luminal cells showing numerous microvilli. The mesenchymal elements were fibroblasts and chondrocytes embedded in a mucous and chondroid matrix. Groups of undifferentiated cells without eccrine differentiation but with ultrastructural features suggestive of epithelial origin were seen among the mesenchymal and epithelial elements of the tumor.