'Mixed' salivary type adenoma of the human female breast

A breast lump in a 46-year-old woman proved on histologic examination to be an adenoma of the "mixed" salivary type (pleomorphic adenoma). The lesion was characterized by intense adenomatous proliferation, hyperplasia of epithelial and myoepithelial cells, myxoid areas, and focal squamous differentiation. Electron microscopy confirmed the myoepithelial nature of islands of stromal cells. The microanatomic pattern, histochemical staining reactions, the presence of elastin, and the ultrastructural features of the tumor, all confirmed the close similarity to the corresponding salivary gland neoplasm.