[1049] Renal Cell Carcinoma: A Study of PMS2 and MSH6 Expression in Histologic Subtypes with Clinicopathologic Correlation

Pamela S Tauchi-Nishi, Diane Chen, Megan Morisada, John Fife, Hiroko Shinoda, David Shimizu. Queens Medical Center, Honolulu, HI; University of Hawaii, Honolulu, HI

Background: Microsatellite instability is seen with varying frequency in renal cell carcinoma (RCC). Previous studies of RCC, ranging from 32 to 127 patients, have utilized immunohistochemical staining for mismatch repair (MMR) proteins MLH1 and MSH2 with varying results. In these articles, loss of expression for MLH1 varied between 7-92% for clear cell RCC, 20-64% for papillary RCC, and 0-58% for chromophobe RCC. In comparison, MSH2 loss ranged from 19-56% for clear cell, 0-62% for papillary, and 0-25% for chromophobe RCC. More recent investigations have demonstrated that MLH1 and MSH2 are the obligatory partners for their respective heterodimers, PMS2 and MSH6, and that the latter proteins may be preferable in the initial screen for MMR abnormalities in extracolonic malignancies. In our study, we examined the 3 main histologic subtypes of RCCA for expression of PMS2 and MSH6, and compared these findings with other clinicopathologic factors.
Design: We identified 75 RCC patients, including 25 of each histologic subtype, within the Queens Medical Center database from January 2008 to July 2012. Immunohistochemical staining of the tumors was performed for MSH6 and PMS2, and the results were correlated with clinicopathologic features, including patient age and gender, tumor location, size, grade, and stage.
Results: All 75 RCC cases expressed PMS2. All 25 clear cell RCCs revealed no loss of MSH6 expression. Six (24%) of the 25 chromophobe RCCs, and 3 (12%) papillary RCCs failed to stain for MSH6. No significant correlations were observed between loss of MSH6 expression and any of the clinicopathologic factors.
Conclusions: Our study demonstrated a possible correlation between non-clear cell histology and loss of MSH6 proteins. There was no association with any other clinicopathologic features.
Category: Genitourinary (including renal tumors)

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 160, Wednesday Afternoon

 

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