Shuch B, Said J, LaRochelle JC et al.
University of California, Los Angeles, CA, USA.
Cancer 2010;116:616–24.
Editor’s note: Renal cell carcinoma (RCC) is the most common histotype of the primary kidney tumors. Approximately 80% of patients with RCC have clear-cell histology. It is well known that some histotypes have mixed histologies, which may include other cell types (e.g. papillary or chromophobe) or sarcomatoid differentiation. The latter is an unfavorable prognostic factor, being associated with a more aggressive disease that usually has a poor response to the different systemic therapies available. Originally, renal tumors with sarcomatoid features were thought to be a separate histological subtype; however, they are now considered to be an unfavorable evolution of RCC.