[Atypical forms of renal carcinoma].

This is a comparative study of the various subtypes of renal carcinoma (divided according to their microscopic features in classic, papillary, Bellini's, sarcomatoid, chromophobe, small cells) on the 286 renal carcinomas removed in the Valdecilla Hospital over the last 25 years. For each type of presentation, age, gender, location, intrarenal status, tumoral diameter, clinical signs and symptoms, presence of metastasis, Fuhrman's core grade, Robson stage and survival, have been analyzed. No cases of small cells or chromophobe tumours were seen. Of the total 286 renal tumours, 253 (88.64%) showed a classical pattern, 21 (7.34%) were papillary, 10 (3.49%) sarcomatoid, and 2 (0.69%) Bellini's carcinomas. In the analysis by mean age at presentation, distribution by sex, involvement site and intrarenal location, no statistically significant differences were found between the different tumoral subtypes. In our series, the sarcomatoid type presents a larger average tumoral diameter than both the papillary and the classical ones (p < 0.01, p < 0.001, respectively). The most frequent clinical manifestation in all tumoral types was haematuria. The sarcomatoid tumours showed a statistically significant trend to present with higher core grade (G4) and higher tumoral stage (E IV) than papillary and classical tumours. Overall survival at 3 years was 72% for the papillary type, 65% for the classical and 22% for the sarcomatoid subtype, the latter being significantly worse than the first two (a < 0.001).