Abstract: Background and purpose: Clear cell papillary renal cell carcinoma is a rare renal epithelial malignant tumor which was recently discovered. Its biological behavior is inert, and its prognosis is good. The purpose of this article was to analyze the clinical and pathological features of clear cell papillary renal cell carcinoma, and differentiate it from other subtypes to avoid overtreatment. Methods: Seven cases of clear cell papillary renal cell carcinoma were collected and analyzed by histopathology and immunohistochemistry. Results: In 7 cases, the masses were all located in the kidneys. The incised surface was grayish red and grayish yellow, solid or cystic. Under the microscope, the tumor tissue was glandular tubular, microcystic, or papillary. The tumor could be a dominant structure or a variety of structures mixed presence. The cytoplasm was clear, the nucleus was round or ovoid, and WHO/ISUP grading was grade 1 or 2. Immunophenotype results showed that 7 cases all expressed CK7, CK8, vimentin, PAX-8, CA9, CK34βE12, and Ki-67 proliferative index 5 % -10 %. However, none of them expressed CD117, TFE3 or CD10. All the patients were followed up for 2 months to 4 years without recurrence or metastasis. Conclusion: Clear cell papillary renal cell carcinoma is a rare low-grade malignant tumor. Morphologically, it overlaps with a variety of renal cancers with clear cells and/or papillary cells, which can be differentiated by immunohistochemistry.

Key words: Clear cell papillary renal cell carcinoma, Immunohistochemistry, Diagnosis, Differential diagnosis