Oncocytic neoplasms of the parotid gland: A 16-year institutional review

BACKGROUND: Oncocytic neoplasms of the parotid gland are a rare collection of salivary gland tumors that include oncocytosis, oncocytoma, and oncocytic carcinoma. Mounting evidence has linked the presence of oncocytes to acquired mitochondrial dysfunction. OBJECTIVES: The study goals were to further delineate this poorly understood group of salivary gland tumors and to search for genetic alterations indicative of mitochondrial dysfunction. METHODS: Cases were identified by search of the surgical pathology archival files from 1984 through 2000. Corresponding medical records were reviewed. Tumor mitochondrial DNA (mtDNA) was evaluated for mtDNA mutations within the control region (C-tract). RESULTS: Twenty-one parotid oncocytic neoplasms were identified. Oncocytoma was the most frequent morphology (62%), followed by oncocytosis (28.5%) and oncocytic carcinoma (9.5%). One specimen displayed synchronous oncocytic morphologies (oncocytoma, oncocytosis, and oncocytic metaplasia). One oncocytoma specimen displayed the mtDNA C-tract alteration. CONCLUSIONS: Oncocytic neoplasia of the parotid gland is a rare form of salivary gland disease with obscure etiology. The presence of multiple oncocytic morphologies in a single specimen is suggestive of transition between forms. Although oncocytic tumorigenesis secondary to acquired mitochondrial dysfunction is a plausible mechanism, few of these tumors actually harbor mtDNA alterations within the control region.