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Immunohistochemical Analysis for Cytokeratin 7, KIT, and PAX2
Value in the Differential Diagnosis of Chromophobe Cell Carcinoma

Lorenzo Memeo MD, Jeffrey Jhang MD, Adel M. Assaad MD, James M. Mckiernan MD, Vundavalli V.V.S. Murty MD, Hanina Hibshoosh MD, Guo-Xia Tong MD, PhD, Mahesh M. Mansukhani MD
DOI: http://dx.doi.org/10.1309/9KWEA4W9Y94D1AEE 225-229 First published online: 1 February 2007

Abstract

Immunohistochemical staining for cytokeratin 7 (CK7), KIT, and PAX2 expression was performed on 91 renal neoplasms, 37 conventional (clear cell) renal cell carcinomas (CRCCs), 20 papillary RCCs (PRCCs), 11 chromophobe RCCs (ChCs), and 23 oncocytomas, with available karyotypes. All ChCs, 19 PRCCs, 2 CRCCs, and 1 oncocytoma were CK7+; all ChCs, 22 oncocytomas, 2 CRCCs, and no PRCCs expressed KIT; PAX2 was positive in 31 CRCCs, 17 PRCCs, 20 oncocytomas, and 1 ChC. The predominant expression profiles were as follows: CRCC, CK7–/KIT–/PAX2+ (26/37); PRCC, CK7+/KIT–/PAX2+ (17/20); ChC, CK7+/KIT+/PAX2– (10/11); and oncocytoma, CK7–/KIT+/PAX2+ (19/23). Cytogenetic analysis showed that the sole PAX2+ ChC had a retained chromosome 10, and all ChCs with chromosome 10 loss were PAX2–. These results identify specific staining patterns of the 4 major histologic subtypes of renal neoplasms and raise the question of a relationship between chromosome 10 loss and loss of PAX2 expression in ChC.

Key Words:
  • Cytokeratin 7
  • KIT
  • PAX2
  • Oncocytoma
  • Renal cell carcinoma