Background: Chromophobe renal cell carcinoma (chRCC) has a favorable prognosis. Due to irregular nuclei and nuclear pleomorphism, chRCC has a high Fuhrman nuclear grade (FNG). The chromophobe tumor grade (CTG) is a novel three-tier grading system that has been reported to be a better prognosticator than the traditional FNG. We compared the two nuclear grading systems in terms of patients' clinical outcomes.
Patients and method: We performed this retrospective chart review of all patients with chRCC from 2000 to 2017. All pathologic features and CTG and FNG results were re-evaluated.
Result: Eighteen patients' records were reviewed with a mean follow-up of 70.6 months. The nuclear grading distribution was as follows: FNG 2, 56%; FNG 3, 39%; FNG 4, 5%; CTG 1, 78%; CTG 2, 17%; and CTG 3, 6%. Only one patient died. This patient had adrenal invasion, lung metastasis, sarcomatoid change and tumor necrosis, and the tumor was graded as FNG 4 and CTG 3. Overall survival was associated with both FNG and CTG.
Conclusion: Chromophobe RCC was associated with a low rate of cancer-specific death and sarcomatoid differentiation. Both FNG and CTG were associated with overall survival.
Keywords: Chromophobe renal cell carcinoma; Chromophobe tumor grade; Fuhrman nuclear grade; Nuclear grading system.