1. Department of Pediatric Hematology and OncologySt. Anna Children's HospitalMedical University of Vienna Vienna Austria
2. Division of Hematology and OncologyDepartment of PediatricsHospital for Sick Children Toronto Canada
3. Department of Pediatric Hematology and OncologyUniversity of Münster Münster Germany
4. Princess Máxima Center for Pediatric Oncology Utrecht The Netherlands
5. Department of Pediatric Hematology and OncologyCambridge University HospitalsNHS Foundation TrustAddenbrooke's Hospital Cambridge United Kingdom
6. Department of Pediatric and Adolescent OncologyGustave‐Roussy Cancer CenterParis‐Saclay University Villejuif France
7. Department of PathologyNecker Enfants Maladies Hospital Paris France
8. Department of PathologyUniversity of Padova Padova Italy
9. Department of PathologyHematopathology Section and Lymph Node RegistryUniversity of Kiel Kiel Germany
10. Division of Pediatric HematologyOncology and Stem Cell TransplantationDepartment of Pediatrics and Adolescent MedicineUniversity Medical Center Aachen Germany
11. Department of Pediatric Hematology and OncologyUniversity of Padova Padova Italy
12. Department of Pediatric Hematology and OncologyThe Royal Marsden NHS Foundation Trust London United Kingdom
13. Division of Cellular and Molecular PathologyDepartment of PathologyAddenbrooke's Hospital Cambridge United Kingdom
14. Central European Institute of TechnologyMasaryk University Brno Czech Republic
15. Department of Pediatric Hematology and OncologyUniversity Hospital Leuven Leuven Belgium
16. Department of Pediatric Hematology and OncologyUniversity Hospital Hamburg, Eppendorf Hamburg Germany
17. Department of Pediatric Hematology and OncologyThe Queen Silvia's Hospital for Children and AdolescentsUniversity of Gothenburg Gothenburg Sweden