Abstract: Objective: To explore the clinicopathologic features and the prognosis of renal cell carcinoma(RCC) with rhabdoid features.Methods: It was reviewed a consecutive series of 135 RCCs during the period from 1999 to 2009.Seven(7/135,5.2%)cases of RCC with rhabdoid features were identified.After immunohistochemistry and optical microscopy were performed,relevant literatures were reviewed.Results: Histopathologically,the RCC of these cases included the regional components of the conventional clear cell RCC and the rhabdoid cells.There was transition or separation with fibrous capsule between rhabdoid cells and conventional RCCs.The rhabdoid regions characterized with lack of adhesion or poor adhesion.The rhabdoid cells were round or polygonal,and exhibited abundant eosinophilic cytoplasm,eccentric nuclei,vesicular chromatin pattern and prominent nucleoli.The hyaline eosinophilic globular inclusions also could be seen in paranuclear cytoplasm.The immunohistochemical study showed that vimentin(7/7),panCK,(7/7),EMA(7/7) and CD10(7/7) were expressed diffusely,and NSE(3/7),S-100 protein(1/7) were expressed focally and weakly,while desmin,myogenin,SMA,CK7,CK20 and HMB45 were expressed negatively in the rhabdoid cells.A distinctive paranuclear spherical structures expressed panCK,EMA,vimentin and CD10 were observed characteristically.The expression of Ki-67 in rhabdoid region was higher than region of the conventional clear cell RCC.The expression of CD34 showed that compared with the conventional clear cell RCC region,vessels significantly reduced in the rhabdoid region.Among 7 cases,6 patients offered the information of follow-up(range from 3 to 96 months),and 3 patients died from 3 months to 1.5 years after diagnosis,1 case was alive with known metastases,the other 2 patients were alive without clinically detectable carcinoma.Conclusions: The RCC with rhabdoid features is a rare neoplasm with highly aggressiveness.There were similar features of histopathology,immunophenotype and ultrastructur between the RCC with rhabdoid features and the RCC without rhabdoid features,and the fomer may be a new subtype of RCC with poor clinnical outcome.