Cytologic diagnosis of the papillary variant of renal-cell carcinoma.

The papillary variant of renal-cell carcinoma is characterized by distinctive histologic, clinical and angiographic features. A study was undertaken to delineate the cytologic features of this tumor as it is encountered in cellular samples. Cytologic specimens containing tumor cells from eight patients who underwent resection for papillary renal-cell carcinoma were examined and compared to corresponding cytologic samples obtained from ten other patients who had nonpapillary renal-cell carcinoma. The cytologic appearance of papillary renal-cell carcinoma, which is deceptively benign, is marked by distinctive papillary structures that often resemble branched chains. The cells are usually small and contain uniform nuclei; numerous macrophages with foamy cytoplasm are often found in the background. These cytologic features were not observed in the cellular specimens from the nonpapillary renal carcinomas. We conclude that papillary renal-cell carcinoma can be confidently recognized in cytologic specimens.