Renal cell carcinoma in children and adolescents: a retrospective study of a French–Italian series of 93 cases

International audience; Aims Renal cell carcinomas (RCCs) represent 2-5% of kidney malignancies in children and adolescents. Appropriate diagnostic and classification are crucial for the correct management of the patients and in order to avoid inappropriate pre-operative chemotherapy, which is usually recommended if a Wilms' tumour is suspected. Methods and results A French-Italian series of 93 renal cell carcinomas collected from 1990 to 2019 in patients aged less than 18 years was reclassified according to the 2016 World Health Organization (WHO) classification and the latest literature. TFE3 and TFEB fluorescence in-situ hybridisation (FISH) analyses and a panel of immunohistochemical stains were applied. The median age at diagnosis was 11 years (range = 9 months-17 years). MiT family (MiTF) translocation RCCs accounted for 52% of the tumours, followed by papillary (20%) and unclassified RCCs (13%). Other subtypes, such as SDHB-deficient and fumarate hydratase-deficient RCCs, represented 1-3% of the cases. We also described a case of ALK-rearranged RCC with a metanephric adenoma-like morphology. Conclusion A precise histological diagnosis is mandatory, as targeted therapy could be applied for some RCC subtypes, i.e. MiTF-translocation and ALK-translocation RCC. Moreover, some RCC subtypes may be associated with a predisposition syndrome that will impact patients' and family's management and genetic counselling. A precise RCC subtype is also mandatory for the clinical management of the patients and inclusion in new prospective clinical trials.