Chromophobe renal cell carcinoma with sarcomatoid differentiation

OBJECTIVE: To investigate the clinicopathologic features of chromophobe renal cell carcinoma with sarcomatoid differentiation. STUDY DESIGN: A search was made through the surgical pathology and expert consult files of two major academic institutions from 2003 to 2011 for cases of chromophobe renal cell carcinoma with sarcomatoid differentiation. RESULTS: Fourteen patients were identified. The patients included 9 males (64%) and 5 females (36%). The mean patient age was 60.4 years (range, 40-82 years). There was a left-sided predominance: left (9 patients) and right (5 patients). The mean tumor size was 14.6 cm (range, 9.5-28.0 cm), and the mean percentage sarcomatoid differentiation was 67% (range, 30-99%). All tumors exhibited moderate to extensive areas of necrosis. The nonsarcomatoid component in all cases demonstrated classic features of chromophobe renal cell carcinoma. Nine patients (64%) had pT3 disease and 5 patients (36%) had pT4 disease. Five patients (36%) had positive surgical margins. Three patients (21%) had tissue diagnosis of metastatic disease at the time of initial surgery. Six patients (43%) had subsequent pathologic and/or radiologic evidence of multiple or isolated metastatic disease. Follow-up information was available in all 14 patients. Mean follow-up time was 16 weeks (range, 2-84 weeks). Ten of 14 patients (71%) died of disease, 9 of those within 6 months (mean survival time of 10 weeks), 3 patients (21%) were alive with disease, and only 1 patient (7%) was alive with no evidence of disease. CONCLUSION: This study is one of the largest series to date specifically examining the clinicopathologic features of sarcomatoid chromophobe renal cell carcinoma in radical nephrectomy specimens and confirms the observation that these tumors behave more aggressively than conventional clear cell renal cell carcinoma or papillary renal cell carcinoma.