Pathologic 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 highly correlated with renal sinus invasion, prospective data on evaluating pathologic stage are limited. We evaluated a large series reported by a single urologic pathologist.
Three hundred consecutive specimens were reviewed. Tumours larger than 5 cm were routinely extensively sampled or grossly re-reviewed when no extrarenal extension was identified on initial examination. Apparent multifocal disease was critically assessed for intravascular spread. Retrograde venous invasion was reported in 15/300 (5%) cases, of which 13/15 were clear cell RCC. Of a total of 163 specimens with clear cell histology, only 5/34 (15%) tumours 7 centimetres or larger were reported as pT2, all of which had an explanatory comment indicating the absence of definitive extrarenal spread. In contrast, 15/20 (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 (p=0.005).
Our findings support that retrograde venous invasion should be carefully considered 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). This article is protected by copyright. All rights reserved.
Histopathology. 2018 Jun 13 [Epub ahead of print]
Kanika Taneja, Sohrab Arora, Craig G Rogers, Nilesh S Gupta, Sean R Williamson
Department of Pathology and Laboratory Medicine, Henry Ford Cancer Institute, Henry Ford Health System, Detroit, MI, USA., Vattikuti Urology Institute, Henry Ford Health System, Detroit, MI, USA.