ABSTRACT
Purpose To investigate the clinicopathological features, immunophenotype, molecular genetic alteration in multilocular cystic clear cell neoplasm of low malignant potential. Methods 17 cases of multilocular cystic clear cell neoplasm of low malignant potential with complete clinical data, systematic measurement and follow-up were retrospectively studied. Histopathological evaluation and immunophenotyping were examed by HE staining and EnVision two steps methods, chromosome 3p deletion was analyzed by interphase fluorescence in situ hybridization. Results In 17 cases, there were 12 males and 5 females, and the ratio of male and female was 2.4: 1. The prevalence age was at a range of 28-73 years, and the average age is54 years. Mostly of them were found by incidental or physical exmanination. Microscopically, most cysts were lined by a single layer of tumor cells with clear cytoplasm, small nuclear, and no obvious nucleoli. According to WHO/ISUP nuclear grade, they were level I. Clear cell groups similar to cells lined cysts were seen within the fibrous septa. Immunohistochemically, tumor cells were positive for CK(AE1/AE3), CK7, EMA, vimentin, CD10, CAIX, PAX-2, and PAX-8, but negative for CD68. Ki-67 index were less than 10％. The loss of heterozygosity of 3p chromosome was detected in 11 cases and the rate of the loss of heterozygosity was 64.7％. Conclusion Multilocular cystic clear cell neoplasm of low malignant potential is a relatively rare type of renal cell carcinoma with low malignant potential and a good prognosis. It is suggested that tumor cells may be derived from tumor stem cells with pluripotent potential in renal tubules based on the immunophenotypes. Multilocular cystic clear cell renal cell carcinoma and renal clear cell carcinoma is similar in immunophenotype and molecular genetics, which suggesting that it may be a special histologic subtype of renal clear cell carcinoma.