Oncocytoma of the Parotid Gland in the Setting of Birt-Hogg-Dube Syndrome.

Birt-Hogg-Dubé syndrome (BHD) is a rare autosomal dominant disorder caused by germline mutations in the FLCN gene, characterized by cutaneous fibrofolliculomas, pulmonary cysts, and an increased risk of renal neoplasms. Parotid oncocytoma is an infrequently reported extracutaneous manifestation of the syndrome. A 30-year-old man with a prior history of testicular embryonal cell carcinoma presented with a right-sided neck mass. Workup of the parotid lesion ultimately led to a new diagnosis of BHD, confirmed by FLCN germline mutation testing. The patient underwent right parotidectomy, which was technically complex due to parapharyngeal extension and adherence to the facial nerve. Final pathology confirmed oncocytoma with clear cell features; all three lymph nodes were negative for metastatic carcinoma. The patient has remained without evidence of disease at over two years of postoperative follow-up. This case illustrates the diagnostic challenges posed by BHD-associated parotid oncocytoma, particularly when clear cell morphology raises concern for metastatic renal cell carcinoma or recurrent germ cell tumor. Clinicians should consider BHD in younger patients presenting with oncocytic parotid tumors, as recognition carries important implications for long-term renal and pulmonary surveillance.