Sarcomatoid renal cell carcinoma: Clinicopathologic. A study of 42 cases

Forty‐two cases of sarcomatoid renal cell carcinoma were reviewed clinicopathologically. Twenty‐four patients were men, and 18 women; average age was 56.2 years (range, 30–81 years). Eight, 9, 13, and 12 cases were Stages I, II, III, and IV, respectively. Three morphologic patterns of sarcomatoid components were identified: malignant fibrous histiocytomatous (26 cases), fibrosarcomatous (6 cases), and unclassified sarcomatoid (10 cases). Mitotic count, degree of pleomorphism, cellularity, and amount of tumor matrix in the sarcomatoid areas, and similar morphologic parameters in the carcinomatous component all failed to correlate with prognosis, as did tumor size and renal vein involvement by tumor. Clinicopathologic stage was a most significant prognostic factor, with a survival of 49.7 months for Stage I and 6.8 months for combined Stages II, III, and IV. Tumor necrosis in the sarcomatoid area and proportion of sarcomatoid components were also poor prognostic factors. When these factors were compared to the stage, necrosis was an independent variable, however, proportion of sarcomatoid components was a poor prognostic indicator only for Stages I and II.