Submandibular gland oncocytoma: Imaging features and histopathological correlation of a rare benign salivary gland tumor

Abstract

Submandibular gland oncocytoma is a rare benign epithelial tumor accounting for less than 1% of all salivary gland neoplasms. It is composed of oncocytes-large polygonal epithelial cells with abundant eosinophilic granular cytoplasm resulting from mitochondrial accumulation-and typically affects adults between the fifth and seventh decades of life, without a clear gender predilection. Radiation exposure has been reported as a possible predisposing factor. Clinically, oncocytomas usually present as painless, slow-growing masses. Imaging modalities, particularly ultrasound and contrast-enhanced computed tomography, typically demonstrate well-circumscribed and homogeneous lesions suggestive of a benign process. Fine-needle aspiration cytology may contribute to the preoperative assessment by suggesting an oncocytic lesion; however, definitive diagnosis relies on histopathological examination of the excised specimen, which remains essential to reliably differentiate oncocytoma from malignant oncocytic neoplasms. The main differential diagnoses include Warthin's tumor, pleomorphic adenoma, and oncocytic carcinoma. Surgical excision of the tumor along with the affected gland is the treatment of choice. Recurrence and malignant transformation are exceedingly rare, and prognosis is excellent following complete resection. We report the case of a 52-year-old male patient with no significant medical history who presented with a slowly enlarging submandibular mass. Imaging findings were consistent with a benign salivary gland tumor, and the diagnosis of oncocytoma was subsequently confirmed by histopathological analysis after surgical excision. Given its rarity and potential diagnostic overlap with other oncocytic lesions, an integrated clinical, radiological, and pathological approach is essential for accurate diagnosis and optimal management.