title: Cytologic and histologic findings in multiple renal hybrid oncocytic tumors in a patient with Birt-Hogg-Dubé syndrome: a case report.
abstract: BACKGROUND
  Birt-Hogg-Dubé (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 highly associated with BHD.
  
  
  METHODS
  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 had excised.
  
  
  CONCLUSIONS
  When multiple kidney tumors from a single patient appear oncycytic on fine needle aspiration, especially when focal clear cells are present, the possibility of oncocytomas and hybrid tumors associated with BHD must be entertained.
authors.affiliation: Department of Pathology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois 60611, USA. b-adley@northwestern.edu
authors.forename: Brian P
authors.initials: BP
authors.lastname: Adley
authors.forename: Kristian T
authors.initials: KT
authors.lastname: Schafernak
authors.forename: Anjana V
authors.initials: AV
authors.lastname: Yeldandi
authors.forename: Ximing J
authors.initials: XJ
authors.lastname: Yang
authors.forename: Ritu
authors.initials: R
authors.lastname: Nayar
mesh_terms: D018249:Adenoma, Oxyphilic / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D003560:Cysts / Q000000981:diagnostic imaging* / Q000473:pathology; D003937:Diagnosis, Differential; D004847:Epithelial Cells / Q000473:pathology; D005260:Female; D005799:Genes, Dominant; D006801:Humans; D007668:Kidney / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D007680:Kidney Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery; D011030:Pneumothorax / Q000000981:diagnostic imaging; D011237:Predictive Value of Tests; D013577:Syndrome; D014057:Tomography, X-Ray Computed