Biomarker Expression in Sarcomatoid Renal Cell Carcinoma: Comparison with Non-Sarcomatoid Components, and Renal Cell Carcinoma Unclassified.
Liang Liu, Qiqin Yin-Goen, Andrew N Young, Adeboye O Osunkoya. Emory University School of Medicine, Atlanta
Background: The biomarker expression of the various subtypes of renal cell carcinoma (RCC) continues to be an area of great interest with clinical, diagnostic and therapeutic significance. The comparison of biomarker expression of sarcomatoid RCC with non-sarcomatoid component has hitherto not been well characterized.
Design: A search was made through the surgical pathology files of an academic institution for cases of RCC with sarcomatoid differentiation. 15 cases were selected; 6/15 (40%) clear cell CCRCC, 6/15 (40%) chromophobe CHRCC, 2/15 (13%) papillary PAPRCC, and 1/15 (7%) clear cell papillary CCPRCC. A case of RCC unclassified (UC) was also included in the study. Tumor cells obtained from separate FFPE tissue blocks of the sarcomatoid and non-sarcomatoid components were microdissected in each case. The relative expression of tumor biomarkers was measured by quantitative RT-PCR. RCC biomarkers were chosen from our previous microarray studies, and included: CCRCC markers CA9 and NNMT; PAPRCC markers AMACR, BAMB1 and SLC34A2; and CHRCC markers PVALB and BDF1. Results were analyzed using bioinformatics software.
Results: The non-sarcomatoid and sarcomatoid CCRCC components showed increased expression of NNMT compared to CA9. The non-sarcomatoid and sarcomatoid CHRCC components showed increased expression of parvalbumin compared to BDF1. The non-sarcomatoid and sarcomatoid PAPRCC components showed increased expression of BAMB1 and AMACR compared to SLC34A2. The non-sarcomatoid component of CCPRCC showed increased expression of CA9, AMACR and BAMB1, while the sarcomatoid component showed only slightly increased expression of SLC34A2. In most cases, the biomarker expression levels were higher in the non-sarcomatoid components compared to the sarcomatoid components. In all cases, the positive tumor biomarker expression levels in the non-sarcomatoid areas were relatively lower than in our previously studied RCC subtypes that had no sarcomatoid component. Expression of NNMT, parvalbumin and BAMB1/AMACR tended to distinguish sarcomatoid CCRCC, CHRCC and PAPRCC respectively from sarcomatoid RCC of other subtypes. The RCCUC case showed broad increased expression of NNMT, BDF1 and BAMB1, confirming a truly mixed phenotype.
Conclusions: Our study suggests that NNMT, parvalbumin and BAMB1/AMACR, are markers of choice for cases of CCRCC, CHRCC and PAPRCC respectively. These markers may have a critical diagnostic role in cases of sarcomatoid RCC in which subtyping is precluded by the absence of the non-sarcomatoid component, especially on needle core biopsies.
Category: Genitourinary (including renal tumors)
Monday, February 28, 2011 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 114, Monday Morning