Immunohistochemical expression of tumor antigens MAGE-A3/4 and NY-ESO-1 in renal oncocytoma and chromophobe renal cell carcinoma.

The distinction between renal oncocytoma (RO) and chromophobe renal cell carcinoma (ChRCC), especially the eosinophilic variant, can often be difficult. Our study has documented for the first time the expression of MAGE-A3/4 and NY-ESO-1 cancer testis antigens (CTAs) in these tumors. A total of 35 patients (17 ROs and 18 ChRCCs) were included in the study. Two antibodies were used for immunohistochemical staining: 57B recognizing multiple MAGE-A and D8.38 recognizing NY-ESO-1 CTAs. Fifteen (88.2%) samples of RO stained positively for both MAGE-A3/4 and NY-ESO-1 antigens. Regarding ChRCC, seven (38.9%) stained positively for MAGE-A3/4 and six (33.3%) for NY-ESO-1 antigens. Median MAGE-A3/4 expression was moderately positive in RO and negative in ChRCC. The difference in MAGE-A3/4 expression between two tumor groups was significant (P=0.0013). Median NY-ESO-1 expression was strongly positive in RO and negative in ChRCC. The difference in NY-ESO-1 expression between two tumor groups was also significant (P=0.0008). Our study has shown that RO had a significantly higher expression of both CTAs. However, additional research is needed to clarify their potential diagnostic implications.