In children, renal cell carcinoma (RCC) is rare. This study is the first report of pediatric patients with RCC registered by the International Society of Pediatric Oncology‐Renal Tumor Study Group (SIOP‐RTSG). Pediatric patients with histologically confirmed RCC, registered in SIOP 93‐01, 2001, and UK‐IMPORT databases, were included. Event‐free survival (EFS) and overall survival (OS) were analyzed using the Kaplan‐Meier method. Between 1993‐2019, 122 pediatric patients with RCC were registered. Available detailed data (n=111) revealed 56 localized, 30 regionally advanced, 25 metastatic, and no bilateral cases. Histological classification according to WHO 2004, including immunohistochemical and molecular testing for transcription factor E3 (TFE3) and/or EB (TFEB) translocation, was available for 65/122 patients. In this group, the most common histological subtypes were translocation type RCC (MiT‐RCC) (36/64, 56.3%), papillary type (19/64, 29.7%), and clear cell type (4/64, 6.3%). One histological subtype was not reported. In the remaining 57 patients, translocation testing could not be performed, or TFE‐cytogenetics and/or immunohistochemistry results were missing. In this group the most common RCC histological subtypes were papillary type (21/47, 44.7%) and clear cell type (11/47, 23.4%). Ten histological subtypes were not reported. Estimated 5‐year (5y) EFS and 5yOS of the total group was 70.5% (95%CI:61.7‐80.6%) and 84.5% (95%CI:77.5‐92.2%), respectively. Estimated 5yOS for localized, regionally advanced, and metastatic disease was 96.8%, 92.3%, and 45.6%, respectively. In conclusion, the registered pediatric patients with RCC showed a reasonable outcome. Survival was substantially lower for patients with metastatic disease. This descriptive study stresses the importance of full, prospective registration including TFE‐testing.

Pediatric renal cell carcinoma (RCC) is a rare type of kidney cancer, most commonly occurring in teenagers and young adolescents. Few relatively large series of pediatric RCC have been reported. Knowledge of clinical characteristics, outcome and treatment strategies are often based on the more frequently occurring adult types of RCC. However, published pediatric data suggest that clinical, molecular and histological characteristics of pediatric RCC differ from adult RCC. This paper summarizes reported series consisting of ≥10 RCC pediatric patients in order to create an up-to-date overview of the clinical and histopathological characteristics, treatment and outcome of pediatric RCC patients.

Background: The SIOP‐Renal Tumor Study Group (RTSG) does not advocate invasive procedures to determine histology before the start of therapy. This may induce misdiagnosis‐based treatment initiation, but only for a relatively small percentage of approximately 10% of non‐Wilms tumors (non‐WTs). MRI could be useful for reducing misdiagnosis, but there is no global consensus on differentiating characteristics.Purpose: To identify MRI characteristics that may be used for discrimination of newly diagnosed pediatric renal tumors.Study Type: Consensus process using a Delphi method.Population: Not applicable.Field Strength/Sequence: Abdominal MRI including T1‐ and T2‐weighted imaging, contrast‐enhanced MRI, and diffusion‐weighted imaging at 1.5 or 3 T.Assessment: Twenty‐three radiologists from the SIOP‐RTSG radiology panel with ≥5 years of experience in MRI of pediatric renal tumors and/or who had assessed ≥50 MRI scans of pediatric renal tumors in the past 5 years identified potentially discriminatory characteristics in the first questionnaire. These characteristics were scored in the subsequent second round, consisting of 5‐point Likert scales, ranking‐ and multiple choice questions.Statistical Tests: The cut‐off value for consensus and agreement among the majority was ≥75% and ≥60%, respectively, with a median of ≥4 on the Likert scale.Results: Consensus on specific characteristics mainly concerned the discrimination between WTs and non‐WTs, and WTs and nephrogenic rest(s) (NR)/nephroblastomatosis. The presence of bilateral lesions (75.0%) and NR/nephroblastomatosis (65.0%) were MRI characteristics indicated as specific for the diagnosis of a WT, and 91.3% of the participants agreed that MRI is useful to distinguish NR/nephroblastomatosis from WT. Furthermore, all participants agreed that age influenced their prediction in the discrimination of pediatric renal tumors.Data Conclusion: Although the discrimination of pediatric renal tumors based on MRI remains challenging, this study identified some specific characteristics for tumor subtypes, based on the shared opinion of experts. These results may guide future validation studies and innovative efforts.Level of Evidence: 3Technical Efficacy Stage: 3

This study aimed to determine the efficacy of different Leucovorin regimens to reduce oral mucositis in children with acute lymphoblastic leukemia after high-dose Methotrexate (HD-MTX). Twelve articles were included in a systematic literature review. Articles were categorized into low/medium/high risk of bias. As no randomized controlled trial assessing the effect of Leucovorin has been performed, the efficacy of Leucovorin to reduce oral mucositis remains unknown. Leucovorin was initiated at 24, 36 or 42 h after HD-MTX at a dose of 15 or 30 mg/m2. No meta-analysis could be performed as treatment regimens differed. When comparing studies with similar HD-MTX doses, we observed lower oral mucositis rates in regimens with higher cumulative doses of Leucovorin and early initiation of Leucovorin after MTX. Even though future studies are necessary, higher cumulative Leucovorin doses and early initiation of Leucovorin after start of MTX seem to reduce oral mucositis.