[895] Chromophobe Renal Cell Carcinoma with Sarcomatoid Differentiation: A Clinicopathologic Study of 12 Cases

SR Lauer, M Zhou, AO Osunkoya. Emory University School of Medicine, Atlanta, GA; The Cleveland Clinic Foundation, Cleveland, OH

Background: Chromophobe renal cell carcinoma (CHRCC) typically has a better prognosis than clear cell renal cell carcinoma (CCRCC) and papillary renal cell carcinoma (PRCC). It is well established that patients diagnosed with CCRCC or PRCC with sarcomatoid differentiation have a poorer prognosis than patients whose tumors do not show sarcomatoid differentiation. However, CHRCC with sarcomatoid differentiation is relatively rare and has not been well studied.
Design: The surgical pathology and expert consultation files of two major academic institutions were searched for radical nephrectomy specimens with CHRCC with sarcomatoid differentiation from 2003 to 2009. Clinicopathologic parameters and follow up information were analyzed.
Results: 12 patients with a diagnosis of CHRCC with sarcomatoid differentiation were identified, including 7 females (58%) and 5 males (42%). The mean patient age was 62 years (range 40-82 years). There was a 2:1 left sided predominance, left (8 patients) and right (4 patients). The mean tumor size was 14.2 cm (range 9.5-23.0 cm), and the mean percentage sarcomatoid differentiation was 70% (range 40-99%). The non-sarcomatoid component in all cases demonstrated classic features of CHRCC. All tumors exhibited moderate to extensive areas of necrosis. 9 patients (75%) had pT3 disease and 3 patients (25%) had pT4 disease. 4 patients (33%) had positive surgical margins. 5 patients (42%) had pathologic and/or radiologic evidence of multiple or isolated metastatic disease. The common metastatic sites were lungs (4 of 5 patients, 80%), lymph nodes (3 of 5 patients, 60%); other sites included mediastinum, adrenal gland, omentum and orbit. Follow up information was available in 11 patients. Mean follow up time was 12 weeks (range 2-32 weeks). 8 of 11 patients (70%) died of disease, 7 of which were within 6 months (mean survival time of 13 weeks), 2 patients were alive with disease, and only 1 patient was alive with no evidence of disease.
Conclusions: CHRCC with sarcomatoid differentiation should be considered in the differential diagnosis of sarcomatoid tumors on renal biopsy. Most patients present at high stage and have a mean survival of 13 weeks. It is thus critical to make the distinction between CHRCC and oncocytoma on biopsies of large renal tumors. This study is one of the largest series to date specifically examining the clinicopathologic features of sarcomatoid CHRCC and confirms that these tumors behave more aggressively than conventional CCRCC and PRCC.
Category: Genitourinary (including renal tumors)

Monday, March 22, 2010 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 128, Monday Morning


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