Fluorescence in situ hybridization as an adjunct tool in the diagnosis of primary and metastatic renal cell carcinoma in fine needle aspiration specimens

We investigated the role of fluorescence in situ hybridization (FISH) in the diagnosis of primary renal neoplasms and lesions suspicious for metastatic renal cell carcinoma. Consecutive fine‐needle aspiration biopsies (FNAB) of 39 renal masses and 41 metastatic tumours suspicious for renal cell origin were assessed with an immunohistochemical panel for CK7, RCC antigen, CD10, AMACR, PAX8, vimentin, and CD117. In addition, FISH was performed using probes for chromosomes 1p, 3p, 7, 17, X, and Y. A total of 31 of 39 primary renal masses and 33 of 41 metastatic tumors suspicious for renal origin demonstrated typical cytological and immunohistochemical (IHC) features of subtypes of renal neoplasms (40 clear cell renal cell carcinoma (RCC), 20 papillary RCC, and 4 renal oncocytomas). FISH analysis of 15 randomly selected cases each of primary and metastatic lesions revealed chromosomal abnormalities consistent with the diagnosis in 73% of these cases. Of 8 primary renal masses demonstrating atypical microscopic features and noncontributory IHC profiles, FISH was helpful in subtyping 5 (62%) of these lesions (2 clear cell RCC, 1 solid variant of oncocytic papillary RCC, 1 mixed clear cell and papillary RCC, and 1 chromophobe RCC with papillary architecture). Of 8 metastatic tumors clinically suspicious for renal cell origin and supportive, but nondiagnostic IHC, FISH revealed supportive chromosomal changes in 6 (75%) cases. In conclusion FISH analysis on FNAB material, even with limited tissue, may be contributory to the diagnosis and subtyping of RCC in diagnostically challenging biopsies. Diagn. Cytopathol. 2014;42:1013–1023. © 2014 Wiley Periodicals, Inc.