MJMR, Vol. 52, No. 1, 5112, pages (21-?1). Safwat et al., 55 Immunohistochemical Expression of Survivin and BM- H1 in Renal Cell Carcinoma Research Article Immunohistochemical Expression of Survivin and B?- H1 in Renal Cell Carcinoma Rabab A. Safwat, Nehad M. Abd El-Maqsoud, Dalia M. Abd El-Rehim, Heba M. Tawfik and Reda F. Abd El-meguid. Department of Pathology, El-Minia Faculty of Medicine Abstract Background: Kidney cancer is the ninth most common cancer in developed countries. According to last registries of Egyptian National Cancer Institute, renal cell carcinoma represents 567MV of all malignant renal tumors. Survivin is a member of the inhibitor of apoptosis protein family that inhibits apoptosis and play a critical role in regulating mitosis and microtubule stability. BM-H1 (also known as PD-L1) is a ligand that inhibits T cell – mediated immunity and has been implicated as a potent negative regulator of antitumor immunity. Methods: The aim of the current study was to investigate the immunohistochemical expression and the relevant clinicopathological significance of survivin and BM-H1 and to study the relationship between the two markers in one hundred cases of RCC tumors including histologically confirmed M5 case of clear renal cell carcinoma, 15 cases of chromophobe renal cell carcinoma, 15 cases of papillary renal cell carcinoma, 2 cases of mixed renal cell carcinoma, 3 cases of granular renal cell carcinoma and 5 cases of sarcomatoid renal cell carcinoma. Results: A significant association was found between nuclear survivin expression and different clinicopathological features including (primary tumor classification, regional lymph involvement, advanced tumor stage, perinephric fat invasion, lymphocytic infiltrate, SSIGN score, MR score (p<57551 for each), tumor size (p=57551), nuclear grading (p=57552) and coagulative tumor necrosis (p=57552). However, no significant association between cytoplasmic survivin expression and any of clinicopatho-logical features. Regarding BM- H1expression, the present study showed positive BM-H1expression in 2c of RCC tumors. A significant association was found between BM-H1 expression and different clinicopathological features including, primary tumor classification, regional lymph involvement, advanced tumor stage, nuclear grading, coagulative tumor necrosis, perinephric fat invasion, lymphocytic infiltrate, SSIGN score, MR score (p<57551) and tumor size (p=57551).Combined expression patterns of both markers revealed 4 immunophenotypes, including 5M(5M) survivin Low /BM- H1 − tumors, 14 (14) survivin Hi /BM-H1 − tumors, c(c) survivin Low /BM-H1 + tumors, and 25 (25) survivin Hi /BM-H1 + tumors. Among them, the survivin Hi /BM-H1 + immunoprofile showed a strong significant association with the more aggressive clinicopathological features including advanced primary tumor classification, regional lymph involvement, advanced tumor stage, coagulative tumor necrosis, perinephric fat invasion, lymphocytic infiltrate, higher SSIGN score and MR score (p<57551) and higher nuclear grading (p=57552). On studying the differential expression of both markers in primary RCC tumors and their corresponding LN metastasis, no significant differences were noticed between primary tumors and their corresponding LN metastasis with high concordance rates were found between both locations. Conclusion: Taken together, it can be speculated that dual expression of survivin and BM- H1can be used to predict RCC tumor aggressiveness. Key words: Survivin _ BM-H1 _ RCC _ Immunohistochemistry Introduction Kidney cancer is the ninth most common cancer in developed countries (1) . It consti- tutes about 3 of all solid neoplasms and ranks 15th as the leading cause of cancer