Cytologic and histologic findings in multiple renal hybrid oncocytic tumors in a patient with Birt-Hogg-Dube syndrome - A case report

Background Birt-Hogg-Dube (BHD) syndrome is a rare autosomal dominant neoplastic syndrome characterized by multiple skin lesions, lung cysts and renal tumors. A variety of histologic types of renal tumors have been reported, including clear cell renal cell carcinoma (RCC), papillary RCC, chromophobe RCC, oncocytoma and a recently described hybrid oncocytic tumor, which is thought to be,be highly associated with BHD. Case We report a case of a 48-year-old woman with BHD who initially presented to our institution with spontaneous pneumothorax and was found to have multiple lung cysts and renal tumors on computed tomography. We describe the fine needle aspiration findings of one of the renal tumors, which was suggestive of so-called hybrid oncocytic tumor. We also describe the gross and histologic findings of the multiple kidney tumors that the patient subsequently bad excised. Conclusion When multiple kidney tumors from a single patient appear oncocytic on fine needle aspiration, especially when focal clear cells are present, the possibility of oncocytomas and hybrid tumors associated with BHD must be entertained.