Diffuse oncocytic hyperplasia of the parotid gland

[Parapharyngeal oncocytoma of the parotid gland--case report]

Oncocytoma is a rare, benign salivary gland tumour with slowly course. It usually occurs in the parotid gland, seldom in submandibular gland. This report presents a case of parapharyngeal oncocytoma of the left parotid gland in 77-year-old patient, treated in 2nd ENT Department of Medical University of Silesia in Zabrze. On the basis of physical examination and preoperative radiologic studies (computed tomography scan of nasopharynx, magnetic resonance imaging, Doppler ultrasonography of carotid and vertebral arteries) the extensiveness of the tumour was determined and the surgical procedure was undertaken. The removal of a whole tumour was performed through a cervical--transpharyngeal approach with midline mandibulotomy. A follow-up of 30 months hasn't revealed any recurrence of the oncocytoma.

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.