[944] Macrophage Related Markers Expression in MITF/TFE Family Renal Translocation Carcinoma, Melanotic Xp11 Translocation Renal Cancer and Pure Epithelioid PEComa (so Called Epithelioid Angiomyolipoma) of the Kidney

Guido Martignoni, Diego Segala, Enrico Munari, Maurizio Pea, Stefano Gobbo, Matteo Brunelli, Franco Bonetti, Claudia Zampini, Claudio Ghimenton, Ondrej Hes, Philippe Camparo, Serena Pedron, Chiara Pastena, Marco Chilosi, John N Eble, Pedram Argani. University of Verona, Verona, Italy; Ospedale Orlandi, Bussolengo, Italy; Ospedale Civile Maggiore, Verona, Italy; Charles University and University Hospital, Plzen, Czech Republic; Hopital Foch, Suresnes, Paris, France; Indiana University School of Medicine, Indianapolis, IN; Johns Hopkins Medical Institutions, Baltimore, MD

Background: Cathepsin K is a lysosomal protease recently described in MITF/TFE family renal translocation carcinomas (tRCC) and angiomyolipoma of the kidney both classic and epithelioid (pure epithelioid PEComa (PEP)). Both tRCC and angiomyolipoma are neoplasms expressing MITF/TFE family transcription factors. Moreover t(6;11) TFEB+ tRCC and PEP constantly immunostain for the melanogenesis markers HMB45 and MART1 such as melanotic Xp11 tRCC. These three tumors can show overlapping morphological and immunohistochemical features and their differential diagnosis can be challenging. In this study we investigated the expression of macrophage markers (CD68-PGM1, CD68-KP1, cathepsin K, CD163) in a series of tRCC, PEP and melanotic Xp11 tRCC, in order to assess their utility to distinguish them.
Design: We studied the immunohistochemical expression of CD68-PGM1, CD68-KP1, cathepsin K and CD163 in 21 tRCC (including 9 PRCC TFE3+ tRCC and 12 t(6;11) TFEB+ tRCC), 5 melanotic Xp11 tRCC and 13 PEP.
Results: All PEP, all t(6;11) TFEB+ tRCC, and all but two, PRCC TFE3+ tRCC express strongly and diffusely cathepsin K whereas the 5 melanotic Xp11 tRCC were weakly positive. CD163 resulted positive in 3 out of 7 PEP and in none of 4 t(6;11) TFEB+ tRCC, 4 PRCC TFE3+ tRCC and 1 melanotic Xp11 tRCC. CD68-KP1 was expressed in all 22 tested tumors (13 PEP, 4 t(6;11) TFEB+ RCC, 1 melanotic Xp11 tRCC, 4 PRCC TFE3+ tRCC) whereas CD68-PGM1 immunostained all 13 PEP, but none of the other neoplasms.
Conclusions: 1) Cathepsin K is consistently expressed in PRCC TFE3+ tRCC, t(6;11) TFEB+ tRCC, melanotic Xp11 tRCC and PEP; 2) CD68-PGM1 is a useful tool for the differential diagnosis between PEP and all the other tRCC, including the HMB45 positive t(6;11) TFEB+ tRCC; 3) the CD68-PGM1 negativity in melanotic Xp11 tRCC seems to relate this tumor more closely to tRCC rather than PEP.
Category: Genitourinary (including renal tumors)

Wednesday, March 21, 2012 9:30 AM

Poster Session V # 102, Wednesday Morning


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