Prognostic relevance of extensive necrosis in renal cell carcinoma

Evidence suggests that the presence of tumour necrosis is an adverse prognostic factor in renal cell carcinoma (RCC). However, it has also been shown that tumour regression, a microscopic feature associated with necrosis, may be a favourable short term prognostic factor in RCC.

Pathology reports of 253 RCCs from 1992 to 2001 were reviewed, and identified 37 tumours with substantial macroscopic or microscopic necrosis. Microscopic pathology, TNM 1997 tumour stage, and clinical follow up were reviewed and correlated with pathological findings. Three cases were rejected because two were diagnosed at necropsy, and a third was the result of renal arterial embolisation.

Twenty of the 34 cases showed <50% necrosis, 10 showed 50-94% tumour necrosis, and four showed >95% tumour necrosis. Follow up data were unavailable in three cases. Nine of the remaining 31 tumours progressed; six were group 3 tumours showing <50% necrosis, three were group 2 tumours showing 50-94% necrosis, and none was a group 1 tumour showing >95% necrosis.

Extensive necrosis (>95% necrosis) is rare in RCC, accounting for only 1.6% of those diagnosed during eight years in this unselected hospital series. The microscopic pattern of necrosis was typical, requiring extensive tumour sampling for definitive tumour diagnosis. Although there were only four patients with extensive necrosis, none developed recurrent or metastatic carcinoma, or died from RCC. Although extensive (>95%) necrosis may imply better short term prognosis after adjusting for tumour pathological TNM stage, it is probably not a prognostic variable in RCC.