Clinical and pathological characteristics of renal cell carcinomas with MiTF translocation.

INTRODUCTION:Microphthalmia Transfactor Family (MiTF) translocation renal cell carcinomas (RCCs) represent a rare subtype of renal cell cancers. They are diagnosed in young patients and have a poor prognosis. The aim of our study was to analyze the clinical and pathological features of patients with MiTF RCC. MATERIAL AND METHOD:We performed a retrospective, monocentric, descriptive study including all patients operated for RCC between January 2015 and January 2023. The diagnosis of MiTF RCC was suspected by immunohistochemistry (IHC) and confirmed by fluorescent in situ hybridization (FISH). Survival data according to histological subtype (MiTF versus ccRCC) were analyzed using the Kaplan-Meier method and compared using a log-rank test. The primary endpoint was recurrence-free survival (RFS). A descriptive cohort analysis was performed. RESULTS:Of the 960 patients included, 19 (2%) had FISH-confirmed MiTF tumors. The median age at diagnosis was 42 years [18-75], the sex ratio was 1.11 females for 1 male, and 4 (21%) patients were immediately metastatic. Median RFS was 21months for patients in the MiTF group and was significantly lower than that of ccRCC patients, HR=4.33 [CI95% 2.06; 9.10; P<0.001]. Of the 11 patients with cT1-T2 tumors, 9 (81.8%) were treated with nephron sparing-surgery, with 2 (22.2%) harbored local recurrence. CONCLUSION:Our study shows that patients with MiTF translocation RCC have a significantly lower RFS than non-MiTF RCC patients. Nephron sparing surgery must be weighted by the high risk of recurrence in this particularly young population. LEVEL OF EVIDENCE: 5: