Diagnostic Criteria for Oncocytic Renal Neoplasms: A Survey of Urologic Pathologists

Renal oncocytoma and chromophobe renal cell carcinoma (RCC) have been long recognized as distinct tumors; however, it remains unknown if uniform diagnostic criteria are used to distinguish these tumor types in practice. A survey was distributed to urologic pathologists regarding oncocytic tumors. Responses were received from 17/26 invitees. Histologically, >1 mitotic figure was regarded as most worrisome (n=10) or incompatible (n=6) with oncocytoma diagnosis. Interpretation of focal nuclear wrinkling, focal perinuclear clearing, and multinucleation depended on extent and did not necessarily exclude oncocytoma if minor. Staining techniques most commonly used included: CK7 (94%), KIT (71%), vimentin (65%), colloidal iron (59%), CD10 (53%), and AMACR (41%). Rare CK7-positive cells (≤5%) was regarded as most supportive of oncocytoma, although an extent excluding oncocytoma was not universal. Multiple chromosomal losses were most strongly supportive for chromophobe RCC diagnosis (65%). Less certainty was reported for chromosomal gain or a single loss. For tumors with mixed or inconclusive features, many participants use an intermediate diagnostic category (82%) that does not label the tumor as unequivocally benign or malignant, typically "oncocytic neoplasm" or "tumor" with comment. The term "hybrid tumor" was used variably in several scenarios. A slight majority (65%) report outright diagnosis of oncocytoma in needle biopsies. The morphologic, immunohistochemical, and genetic characteristics that define oncocytic renal tumors remain incompletely understood. Further studies correlating genetics, behavior, and histology are needed to define which tumors truly warrant classification as carcinomas for patient counseling and follow-up strategies.

Human pathology. 2017 Mar 14 [Epub ahead of print]

Sean R Williamson, Ramya Gadde, Kiril Trpkov, Michelle S Hirsch, John R Srigley, Victor E Reuter, Liang Cheng, L Priya Kunju, Ravi Barod, Craig G Rogers, Brett Delahunt, Ondrej Hes, John N Eble, Ming Zhou, Jesse K McKenney, Guido Martignoni, Stewart Fleming, David J Grignon, Holger Moch, Nilesh S Gupta

Department of Pathology and Laboratory Medicine, Detroit, MI, United States; Henry Ford Cancer Institute, Henry Ford Health System, Detroit, MI, United States; Department of Pathology, Wayne State University School of Medicine, Detroit, MI, United States. Electronic address: ., Department of Pathology and Laboratory Medicine, Detroit, MI, United States., Department of Pathology and Laboratory Medicine, Calgary Laboratory Service and University of Calgary, Calgary, AB, Canada., Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States., Department of Pathology and Molecular Medicine, McMaster University, Hamilton, ON, Canada., Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, United States., Department of Pathology and Laboratory Medicine, Indiana University, Indianapolis, IN, United States., Department of Pathology, University of Michigan School of Medicine, Ann Arbor, MI, United States., Vattikutti Urology Institute, Henry Ford Health System, Detroit, MI, USA., Department of Pathology and Molecular Medicine, Wellington School of Medicine and Health Sciences, University of Otago - Wellington, Wellington, New Zealand., Department of Pathology, Charles University in Prague, Faculty of Medicine in Plzeň, Pilsen, Czech Republic., Department of Pathology, New York University Medical Center, New York, NY, United States., Robert J. Tomsich Pathology and Laboratory Medicine Institute, Cleveland Clinic, Cleveland, OH, USA., Department of Pathology and Diagnostics, University of Verona, Verona, Italy; Department of Pathology, Pederzoli Hospital, Peschiera del Garda, Italy., Department of Cellular and Molecular Pathology, University of Dundee, Ninewells Hospital, Dundee, United Kingdom., Department of Pathology, University Hospital Zurich, Zurich, Switzerland., Department of Pathology and Laboratory Medicine, Detroit, MI, United States; Henry Ford Cancer Institute, Henry Ford Health System, Detroit, MI, United States.