A Case of Clear Cell Papillary Renal Cell Tumor: A Rare Entity With an Unusual Presentation

Clear cell papillary renal cell Tumor (CCPRCT) is a rare variant of renal cell carcinoma that typically arises in a nonfunctional kidney. We report a case of CCPRCT in a 49-year-old Iranian male who presented with a mural nodule within a large cystic mass in his nonfunctional left kidney, and we discuss the relevant diagnostic challenges. Immunohistochemistry revealed diffuse and intense positivity for CK7 and carbonic anhydrase IX in a cuplike distribution, p53 positivity, and no expression of AMACR or CD10. Ki67 staining showed approximately 5% positivity in neoplastic cells. The differential diagnoses include clear cell and papillary renal cell carcinomas and papillary adenoma, all of which share overlapping clinical, imaging, histopathologic, and immunophenotypic features with CCPRCT. Accurate histological and immunophenotypic evaluation is crucial, as CCPRCT is clinically indolent, and correct diagnosis significantly influences patient outcomes and quality of life.