Fine Needle Aspiration of Oncocytic Neoplasm of the Salivary Gland: Prominent Arborizing Fibrovascular Tissue Fragment With Bland Oncocytes Is an Underrecognized Characteristic Feature of Oncocytoma

Salivary gland neoplasms with oncocytic cells consist of mixed benign and malignant entities. On fine needle aspiration, a commonly encountered challenge is to distinguish oncocytoma from acinic cell carcinoma due to overlapping cytologic features. In this study, we evaluated fine needle aspiration cytology of 11 histologically confirmed oncocytomas and acinic cell carcinomas. We found prominent arborizing fibrovascular tissue fragments with bland oncocytes in five out of six oncocytoma cases, whereas only one of five acinic cell carcinomas had this finding. Our conclusion is that prominent arborizing fibrovascular tissue fragment with bland oncocytes is an underrecognized characteristic feature of oncocytoma. Although this feature is not entirely specific for oncocytoma, it is important to consider oncocytoma as one of the main differential diagnoses when this feature is present and avoid misdiagnosing such cases as acinic cell carcinoma in the absence of other supporting findings.