Oncocytic lipoadenoma of the parotid gland: Report of a rare case

Background: Oncocytic lipoadenoma is a very uncommon, benign, salivary gland tumor. There are only rare case reports of this distinct entity. Case: A 50-year-old-female patient presented with a slow growing swelling, in the left parotid region which was clinically interpreted as a soft tissue tumor, with a differential of neurofibroma/lipoma. Based on fine needle aspiration cytology (FNAC), a diagnosis of oncocytoma with a remote possibility of an 'acinic cell carcinoma with oncocytic features' was suggested. Histopathologic examination showed it to be an encapsulated tumor with an intimate admixture of mature fat cells and oncocytes. The latter was present in glandular or microacinar pattern. The cells were positive for pancytokeratin and epithelial membrane antigen and negative for smooth muscle actin. Conclusions: Histopathologists should be aware of an entity called oncocytic lipoadenoma of the salivary gland in order to differentiate it from other oncytic and lipomatous lesions of salivary gland and diagnose it precisely.