Comparison of type I and II papillary renal cell carcinoma (RCC) and clear cell RCC

To compare the pathological features of clear cell renal cell carcinoma (ccRCC) with papillary RCC (pRCC) and further differentiate type I and II pRCC as independent prognosticators for survival.

From September 1994 to February 2007 557 RCCs were treated and reviewed. All patients underwent radical nephrectomy or nephron-sparing surgery. We reviewed patient data and correlated RCC subtypes to tumour size, pathological stage, nuclear grade, and 5-year cancer-specific survival (CSS). pRCC was re-evaluated in to type I and II. The 2002 Tumour-Node-Metastasis and Fuhrman classifications were used.

In all, 391 (70%) patients had ccRCC, 96 (17%) had pRCC, 34 (6%) had chromophobe RCC, seven (1%) had ductus Bellini RCC and 29 (5%) had unclassified RCC. Upon re-evaluation 34 patients had type I pRCC and 62 had type II. The pRCCs were significantly smaller than the ccRCCs, at a mean (sd) of 4.5 (2.5) cm vs 5 (2.9) cm (P = 0.013), and multifocal (25% vs 12%, P = 0.001). Whereas patients with ccRCC had significantly more primary metastases (12% vs 3%, P = 0.014). The mean (sd) follow-up was 42.3 (41.4) months. The 5-year CSS for M0 patients was 84% for ccRCC and 90% for pRCC (P = 0.573). At multivariate analyses predictors for 5-year CSS were only tumour size (hazard ratio, HR 2.6, P < 0.001), pathological stage (HR 3.9, P < 0.001) and nuclear grade (HR 2.7, P < 0.001). The type I and II pRCCs had significantly different lymphovascular invasion (LVI) and 5-year CSS rates (94% vs 74%, P = 0.03).

The ccRCCs were significantly larger at diagnosis than the pRCCs. The histological subtype (pRCC vs ccRCC) had no impact on the 5-year CSS in multivariate analyses. The type I and II pRCCs had similar histopathological features except for a significant difference in LVI. However, the 5-year CSS was significantly different in type I and II pRCC.