[1039] t(6;11) Renal Cell Carcinoma (RCC): Report of Six New Genetically-Confirmed Cases and Expanded Immunohistochemical (IHC) Profile Emphasizing Renal Tubular Markers

Nathaniel Smith, Peter Illei, Nilda Gonzalez, Victor Reuter, George Netto, Pedram Argani. Johns Hopkins Medical Institutions, Baltimore, MD; Memorial Sloan-Kettering Cancer Center, New York, NY

Background: Renal cell carcinoma (RCC) harboring the t(6;11) (p21;q12) translocation and resulting Alpha-TFEB gene fusion were officially recognized by the 2012 International Society of Urological Pathology Consensus Conference and only approximately 30 genetically confirmed cases have been reported. While these RCC are known to underexpress cytokeratins and label for melanocytic markers HMB45 and Melan A and the cysteine protease Cathepsin K by immunohistochemistry (IHC), a comprehensive IHC profile has not been reported.
Design: We report 6 new t(6;11) RCC, all confirmed by break-apart TFEB fluorescence in situ hybridization. A tissue microarray containing these cases and seven others (13 total genetically confirmed cases of t(6;11) RCC) was constructed and immunolabeled for 15 different antigens. For PAX8 and Ksp-cadherin, whole sections of additional cases were also labeled. Labeling in >10% of cells was considered a positive result whereas labeling in 1-10% of cells was considered focal positive.
Results: The 6 new t(6;11) RCC affected patients aged 3-23 years of age. t(6;11) RCC labeled frequently for PAX8 (12 of 21 cases), RCC Marker antigen (9 of 13 cases), CD117 (9 of 13 cases), and vimentin (9 of 13 cases). A majority of cases labelled focally for CD10 (9 of 13 cases). A subset of cases labeled for racemase (3 of 13 cases). Only rare focal labeling was seen for EMA (1 of 13 cases), PAX2 (2 of 13 cases), and Ksp-cadherin (3 of 19 cases). There was no significant labeling for CAIX, inhibin, SOX10, ER, EP-CAM, or MiTF.
Conclusions: IHC labeling for PAX8, CD10, and RCC Marker antigen supports classification of these neoplasms as RCC despite frequent negativity for cytokeratins and EMA. CD117 and vimentin labeling are more frequent in the t(6;11) RCC compared to the related Xp11 translocation RCC which only rarely express these antigens (Am J Surg Path 2010;34: 1295-1303). In contrast to a recent report (Am J Surg Path 2012;36: 1327-1338), we find that Ksp-cadherin is not a consistent marker of the t(6;11) RCC.
Category: Genitourinary (including renal tumors)

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 158, Monday Morning


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