Further evidence for adipocytic differentiation by the neoplastic myoepithelium.

Lipomatous pleomorphic adenoma (PA)/myoepithelioma is rare. Nevertheless, adipocytic differentiation in salivary gland tumors is a well-known phenomenon. As extensive lipometaplasia occurs primarily in adenomas with myoepithelial participation, circumstantial evidence implicates neoplastic myoepithelium (NME), especially the spindle type, as a key partaker. We report here a unique PA that represents an equivocal transition from the epithelioid NME to adipocytes in recurrent lesions but not in a primary tumor.