1. Biostatistics and Epidemiology Unit, Institut Gustave-Roussy, Villejuif, France;
2. University Paris-Sud, Le Kremlin-Bicêtre, France;
3. Department of Pediatric Hematology and Oncology, Justus Liebig University, Giessen, Germany;
4. Department of Pediatrics, Addenbrookes Hospital, Cambridge; United Kingdom;
5. Inserm, U563, Centre de Physiopathologie de Toulouse Purpan; Université Toulouse III Paul-Sabatier; Toulouse, France;
6. Department of Pathology, Centre Hospitalo-Universitaire Toulouse, Hôpital Purpan, Toulouse, France;
7. Department of Pathology, Hematopathology Section and Lymph Node Registry, University of Kiel, Kiel, Germany;
8. Department of Pathology, Gloucester Hospitals National Health Service Foundation Trust, Gloucester, United Kingdom;
9. Department of Pediatric Hematology and Oncology, Medizinische Hochschule Hannover, Hannover, Germany; and
10. Department of Pediatrics, Institut Gustave-Roussy, Villejuif, France