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.