Papillary renal cell carcinoma: clinicopathological characteristics in 40 patients

Background Two different subtypes of papillary renal cell carcinoma (PRCC) have so far been identified, type-1 with small cells and pale cytoplasm and type-2 with large cells and eosinophilic cytoplasm. It has generally been accepted that type-1 tumors have favorable features in comparison with type-2 tumors, suggesting that these subtypes could be different clinicopathological entities, and, as a result, that the subtypes need to be characterized. Forty cases of PRCCs were reviewed, with special attention to the distinct clinicopathological difference and the response to cytokine therapy. Methods Thirty-five cases of PRCC diagnosed between January 1997 and August 2007 were reviewed. PRCCs were classified according to the criteria of Delahunt and Eble. Results Of these 40 patients, 20 and 20 were diagnosed to be type-1 and type-2 PRCCs, respectively. No lymphatic or vascular invasion or distant metastasis were observed in patients with type-1 PRCC. The nuclear grade in all type-1 PRCCs was low grade. The nuclear grade (P <= 0.01) and the positive rate of vascular invasion (P <= 0.05) was significantly higher in type-2 than in type-1 PRCCs. Distant metastasis was detected preoperatively in three patients with type-2 PRCC. One patient with metastatic type-2 PRCCs demonstrated a response to IL-2 therapy. Conclusion PRCCs include two distinct morphological types of tumor and type-2 PRCCs tends to have unfavorable features in comparison with type-1 PRCCs. These results support the clinical basis for the need to perform morphological subtyping of PRCCs when clinically evaluating such patients.