Renal cell carcinoma (RCC) with rhabdoid differentiation is thought to portend a poor prognosis, similar to RCC with sarcomatoid differentiation. According to the most recent International Society of Urological Pathology (ISUP) grading system, both features are currently classified as grade 4 RCC.
To determine the differential effects of rhabdoid and sarcomatoid differentiation on patient outcome, Mayo Clinic researchers, first author Brian Costello, M.D., reviewed a large series of patients with grade 4 RCC. The study, published in European Urology, identified 406 patients with ISUP grade 4 RCC, including 111 with rhabdoid differentiation.
In multivariable analysis of grade 4 RCC tumors, the presence of rhabdoid differentiation was not associated with death from RCC. In contrast, sarcomatoid differentiation was significantly associated with death from RCC. Patients with RCC with rhabdoid differentiation were significantly more likely to die of RCC than a comparison cohort of 1,758 patients with grade 3 RCC.
These results suggest that rhabdoid and sarcomatoid differentiation should not be grouped together when assessing risk in a patient with grade 4 RCC, but support the notion that rhabdoid differentiation is appropriately placed in the ISUP grade 4 category.
Additional Mayo Clinic authors include: Ben Zhang, M.D., John Cheville, M.D., R. Houston Thompson, M.D., Christine Lohse, Stephen Boorjian, M.D., and Bradley Leibovich, M.D.