Epithelial and Myoepithelial Oncocytes: Ultrastructural Study of a Salivary Gland Oncocytoma

Abstract

An oncocytoma of the submaxillary gland was examined by light and electron microscopy. Two different types of oncocytes were seen. The most prevalent was the usual polyhedral, epithelial oncocyte. The second type of oncocyte has not previously been described, to our knowledge, and consisted of an elongated cell with myofibrils and mitochondrial hyperplasia, a myoepithelial oncocyte. It is concluded that, regardless of cell type, an oncocyte should be defined by the ultrastructural characteristic of mitochondrial hyperplasia. The fine structural features of the hyperplastic mitochondria suggest that they may be secondary to quantitative mitochondrial enzyme(s) deficiency.