Thirty-one cases of low-grade renal cell carcinoma (RCC) with clear cells and tubulopapillary/papillary architecture were analyzed retrospectively with immunohistochemical and genetic markers to gain more experience with the differential diagnosis of such cases. All samples coexpressed CK7 and CA9; the TFE3 or TFEB reactions were negative; the CD10 and the AMACR stainings were negative in 27 cases and 30 cases, respectively. The FISH assays for papillary RCC, available in 27 cases, and deletion of chromosome 3p, available in 29 cases, gave negative results. The results for 3p deletion, VHL gene mutation or VHL gene promoter region hypermethylation testing, along with the diffuse CD10-positivity in 2 cases confirmed 21 cases as clear cell papillary RCC (CCPRCC; CK7+, CA9+; no 3p loss, no VHL abnormality) and 10 cases as clear cell RCC (CCRCC; CK7+, CA9+; no 3p loss, VHL abnormality mutation/hypermethylation present). In CCPRCCs, the representative growth pattern was branching tubulo-acinar, commonly accompanied by cyst formation. The linear nuclear arrangement or cup-shaped staining of CA9 did not necessarily indicate CCPRCC, and the absence of these did not exclude the diagnosis of CCPPRC. One tumor infiltrated the renal sinus; the others exhibited pT1 stage; and metastatic outcome was not recorded. The CCRCC cases were in pT1 stage; 6 exhibited cup-shaped staining of CA9, and 1 displayed lymph node metastasis at the time of surgery. Distant metastatic disease was not observed. In summary, the VHL abnormalities distinguished the subset of CCRCC with diffuse CK7-positivity and no 3p loss from cases of CCPRCC.
Pathology oncology research : POR. 2019 Oct 26 [Epub ahead of print]
Áron Somorácz, Levente Kuthi, Tamás Micsik, Alex Jenei, Adrienn Hajdu, Brigitta Vrabély, Erzsébet Rásó, Zoltán Sápi, Zoltán Bajory, Janina Kulka, Béla Iványi
2nd Department of Pathology, Semmelweis University, Üllői út 93, Budapest, H-1091, Hungary. ., Department of Pathology, University of Szeged, Szeged, Hungary., 1st Department of Pathology and Experimental Cancer Research, Semmelweis University, Budapest, Hungary., 2nd Department of Pathology, Semmelweis University, Üllői út 93, Budapest, H-1091, Hungary., Department of Urology, University of Szeged, Szeged, Hungary.