The diagnostic value of EMA expression in the renal parenchyma tumors.

Renal parenchyma tumors are a heterogeneous group of malignancies that are difficult to diagnose and classify. Immunohistochemistry begun to be routinely used for the diagnosis of these tumors. Panels of antibodies are developed for the diagnostic assessment of these tumors, which include cytokeratins, epithelial membrane antigen and vimentin. Epithelial membrane antigen (EMA) is expressed by most of the tumor cell types. Forty-seven specimens of renal parenchyma tumors were studied immunohistochemically for the expression of EMA. In the majority of the cases, clear cells carcinoma was positive for EMA (25/33, 75.70%). All of the papillary carcinomas were positive, with different staining patterns between the two subtypes. The two cases of chromophobe cells carcinomas were intensely positive with a granular cytoplasmic staining pattern. The mixed epithelial-stromal tumor was negative for EMA in both of the components. Out of the three cases of sarcomatoid carcinomas, one was negative, one was weakly positive (+1) and the last was positive (+2). Intensely positive normal tubes were caught by the tumor proliferation in the negative case and in the negative stained areas of the weakly positive case.