OBJECTIVETo study the clinicopathological features, differential diagnosis and prognosis of clear cell papillary renal cell carcinoma (CCPRCC).

METHODSThe histological, immunohistochemical, and molecular features were studied in 11 cases and follow-up data were also analyzed.

RESULTSThere were a total of 3 females and 8 males. The age of patients were ranged from 33 to 72 years(mean age 52.5 years). The diameters of tumors varied from 1cm to 4 cm. Histologically, papillary and cystic architecture were present at least focally in all tumors. The papillae were covered by small to medium-sized cuboidal cells with abundant clear cytoplasm and often showed extensive secondary branching, which were often folded and densely packed, resulting in a solid appearance. The nuclei were round and uniform in shape; nucleoli were not prominent (Fuhrman grade 1 or 2). Neither mitotic figures nor necrosis was present. All 11 cases exhibited moderate to strong positivity for CK7, CA9, vimentin, and HIF-1α, coupled with negative reactions for CD10, P504S, and TFE3. Ksp-cadherin was positively expressed in 8 cases.VHL gene mutations were not found in all 11 cases. Losses of chromosomes 3 (monoploid chromosome 3) was detected in 3 cases.

CONCLUSIONSCCPRCC is uncommon and seemed to be an indolent tumor. The differential diagnosis should be included tumors, which harbor clear cell and papillary structure including clear cell renal cell carcinoma, papillary renal cell carcinoma, Xp11 translocation renal cell carcinoma, and CCPRCC. Immunohistochemical and molecular analysis may be help for its diagnosis.