Fine needle aspiration cytology of oncocytic lipoadenoma of the parotid gland: report of a rare case.

Background: Oncocytic lipoadenoma is an uncommon benign salivary gland tumor. There are only rare case reports of this distinct entity in which only the histopathologic aspects are discussed. Fine needle aspiration cytologic (FNAC) findings of oncocytic lipoadenoma have not yet been documented.

Case: A 50-year-old woman presented with a slow-growing swelling in the left parotid region that was clinically interpreted as a soft tissue tumor, with a differential of neurofibroma/lipoma. FNAC showed moderate cellularity, with oncocytic cells arranged predominantly as microacini in a prominent lipoid background. The adipose tissue background of the cytologic smears was ignored as material derived from the normal fat tissue; based on the oncocytic population of cells, a diagnosis of oncocytoma was considered. A remote possibility of acinic cell carcinoma with oncocytic features was also suggested. However, histopathologic examination showed it to be an oncocytic lipoadenoma, a tumor we were unaware of at the time of cytodiagnosis.

Conclusion: Both cytopathologists and histopathologists need to be aware of oncocytic lipoadenoma of the salivary gland in order to diagnose it precisely. The clinicocytopathologic correlation highlighted in our case will be useful for cytopathologists in preoperative interpretation and diagnosis.