Clear cell papillary renal cell carcinoma

These tumors account for 1%-4% of renal tumors and are not gender specific. They are disseminated or associated with end-stage renal disease or VHL syndrome. These tumors are small, well-defined, and enveloped masses, often with cystic changes. The histology is papillary, with uniform cell size, clear cytoplasm, nuclei arranged away from the basement membrane, and visible cytoplasmic protrusions, with graded G1 or G2 nuclei. Immunohistochemistry showed diffuse positivity for CK7, cupping positivity for CAIX, positivity for PAX2, PAX8 and CK34βE12, and negativity for P504S and CD10. It should be noted that in morphologically atypical cases: if P504S or CD10 is positive and CK7 diffuse positivity is diminished, the diagnosis of clear cell carcinoma is better.