Cytodiagnosis of Oncocytoma of Parotid Gland: A Report of Two Cases

Abstract

Among benign neoplasms of the salivary gland, malignancies are less common. One of the rarest tumours found in the oral cavity is oncocytoma, comprising less than 2% of all oral neoplasms and carrying a 1% risk of malignant transformation. Oncocytoma is rare among benign neoplasms, typically affecting females and impacting the major salivary glands. Literature discussing the cytodiagnosis of oncocytoma through Fine Needle Aspiration Cytology (FNAC) is even scarcer. Cytomorphological features indicating a predominantly oncocytic population with benign nuclear characteristics suggest the diagnosis of oncocytoma. The presence of oncocytes alongside other cell types in cytology smears suggests oncocytosis or a tumour-like presentation of Warthin’s tumour. Due to its unique features and clinical presentation, clinicians may misdiagnose this tumour as pleomorphic adenoma, haemangioma, or another form of oncocytosis due to its rarity and clinical features. Therefore, only histopathological examination can provide a definitive diagnosis. The present report discusses two unusual cytodiagnoses of oncocytoma identified through FNAC of the parotid gland in a 50-year-old female and a 70-year-old male, along with their clinicoradiological findings and subsequent tumour excision. Furthermore, the authors aim to raise awareness about the importance of a comprehensive work-up and optimal treatment selection for these lesions.