MALIGNANT ONCOCYTOMA OF MAJOR SALIVARY-GLANDS - REPORT OF A POSTIRRADIATION CASE

The fourth case of malignant oncocytoma arising in the submandibular g land is here reported. This tumor arose in a 48-year-old man after rad iation exposure, a finding never described before for malignant oncocy toma. In addition, several regional metastatic lymph nodes were found. The diagnosis was confirmed by histochemical and ultrastructural find ings. The tumor cells showed easily recognizable mucus production and, ultrastructurally, abundant mitochondria, intracytoplasmic lumina lin ed by microvilli and lipid droplets. These last features have only sel dom been described in malignant oncocytoma. Furthermore, the neoplasti c cells were alpha-l-antitrypsin positive and S100, thyroglobulin, car cinoembryonic antigen, and smooth muscle actin negative. A thorough re view of the literature is also presented.