Oncocytic Lipoadenoma of the Parotid Gland against a Background of Multifocal Oncocytic Hyperplasia: Report of a Rare Case

Abstract

Oncocytic lipoadenoma is an extremely rare benign salivary gland tumor with only few cases reported in the literature. We herein report a case of oncocytic lipoadenoma originating in the parotid gland of a 65-year-old man. The tumor presented as a slowly growing asymptomatic right-sided parotid gland mass. On MRI, right parotid showed a 40 × 32 × 20 mm well-encapsulated, neoplastic mass in the superficial lobe. On core biopsy, differentials considered were nodular oncocytosis and oncocytoma. Subsequently, superficial parotidectomy was performed. The resected tumor was encapsulated, yellowish brown, and homogenous. Microscopically, it was composed of oncocytoma-like epithelial component admixed with mature adipocytes, each contributing to 50% of the mass. Adjacent salivary gland showed multiple foci of oncocytosis. Differential diagnosis includes lipomatous tumors as well as neoplastic and non-neoplastic oncocytic lesions of the salivary gland. The present case of oncocytic lipoadenoma against a background of multifocal oncocytic hyperplasia has been reported for its rarity.

Keywords

• mature adipocytes
• oncocytic lipoadenoma
• oncocytosis
• parotid neoplasm