Pathological staging of renal cell carcinoma: a review of 300 consecutive cases with emphasis on retrograde venous invasion.

AIMS: Pathological staging of renal cell carcinoma (RCC) can be challenging compared to other cancer types, as invasion often manifests as finger-like protrusions into vascular spaces or renal sinus tissue. Although prior studies have shown larger tumour size to be correlated highly with renal sinus invasion, prospective data on evaluating pathological stage are limited. We evaluated a large series reported by one urological pathologist. METHODS AND RESULTS: Three hundred consecutive specimens were reviewed. Tumours larger than 5 cm were routinely sampled extensively or grossly re-reviewed when no extrarenal extension was identified on initial examination. Apparent multifocal disease was assessed critically for intravascular spread. Retrograde venous invasion was reported in 15 of 300 (5%) cases, 13 of 15 of which were clear cell RCC. Of a total of 163 specimens with clear cell histology, only five of 34 (15%) tumours 7 cm or larger were reported as pT2, all of which had an explanatory comment indicating the absence of definitive extrarenal spread. In contrast, 15 of 20 (75%) pT2 tumours were non-clear cell histology (papillary, chromophobe and translocation-associated). Comparing pT3a or higher tumours, the median tumour size in cases with retrograde venous invasion was 8.0 cm, compared to 6.2 cm in cases without retrograde venous invasion (P = 0.005). CONCLUSIONS: Our findings support that retrograde venous invasion should be considered carefully before diagnosing multifocal clear cell RCC, which is rare in the sporadic setting. In the absence of vascular invasion, multifocal clear cell papillary RCC can be a mimic. pT2 occurs more frequently with non-clear cell histology (particularly papillary or chromophobe RCC)