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

Renal carcinomas are a heterogeneous group of tumors, difficult to classify and identify precisely. Since their prognosis depends very much upon their type, precise diagnosis might mean the difference between therapeutic success and patient death. Cytokeratins are particularly useful for the identification of the epithelial nature of the tumors, because their expression is maintained even in poorly differentiated tumors. Monoclonal cytokeratins such as CK7 and CK20 stain different components of the renal tubular system and are a useful duo for the identification of the origin of the different tumors that might arise in the kidney. Along with polyclonal cytokeratins such as AE1/AE3 and high molecular weight cytokeratin antibodies (34betaE12, Cam 5.2), epithelial membrane antigen (EMA) and vimentin, they are included in every diagnostic panel for renal tumors. We have selected 138 renal parenchyma tumor specimens, performed morphological diagnosis and then stained them with polyclonal cytokeratin antibody AE1/AE3, and monoclonal antibodies to CK7 and CK20. AE1/AE3 was expressed in 61.7% of the renal parenchyma tumors, with high intensity and percentage of positive cases in the papillary carcinomas (100%), and with rare and weakly positive cells in chromophobic cells carcinomas, clear cells carcinomas and sarcomatous carcinomas. CK7 was positive in 68% of the renal parenchyma tumors, with positive reaction in 100% of the cases of chromophobic cells and sarcomatous carcinomas. Clear cells carcinomas had the less percentage of positive cells, whereas papillary carcinomas were positive in seven out of eight cases. No difference in the staining pattern was noticed between type I and type II papillary carcinomas. CK20 was negative in all cases studied.