Abstract: Objective：To study the characteristics of histopathologic features of small renal carcinoma. Methods: This retrospective study collected the data of renal cell carcinoma from the patients who underwent surgery from January 2002 to June 2012. They were all preoperatively diagnosed as renal cancer by CT scan, and pathologically diagnosed as renal cell carcinoma after surgery with the diameter ≤4 cm. We recorded and analyzed the tumor size, histologic subtype, Fuhrman grading, TNM stage, the existence of tumor vascular invasion, sarcomatoid differentiation, and whether it was multifocal, and then grouped them for comparison. Results: A total of 1 276 patients were included in the study and were analyzed, of whom 306 (24.0%) had small renal cell carcinoma less than 2.0 cm, 526 (41.2%) 2.0-3.0 cm, and 444 (34.8%) bigger than 3.0 cm. Of all the subjects, 1 158 (90.7%) suffered from clear cell carcinoma, 49 (3.8%) papillary carcinoma, 32 (2.5%) chromophobe cell carcinoma, whose distribution was not related with tumor size. Of the ≤2.0 cm and >2.0 cm groups, Furmann grades of G3/4 were 15 (4.9%), 98 (10.1%), respectively (P=0.007). T3a+ stage and above were 1 (0.3%), and 32 (3.3%), respectively (P=0.004). Synchronous distant metastases occurred in 6 patients, all in group >2.0 cm. Tumor sarcomatoid differentiation (0.3% vs. 0.9%), vascular invasion (0.6% vs. 2.1%) and multifocal (1.3% vs. 2.7%) had no significant difference between the two groups. Conclusion:Small renal cell carcinoma with diameter over 2.0 cm are more aggressive, suggesting that renal cancer bigger than 2.0 cm in diameter should not select a nonsurgical treatment.

Key words: Carcinoma, renal cell, Neoplasm staging, Neoplasm metastasis, Urologic surgical procedures