1. Non-Hodgkin Lymphoma-Berlin-Frankfurt-Münster Study Center, Department of Pediatric Hematology and Oncology, Justus-Liebig University, Giessen, Germany;
2. Department of Pediatric Hematology and Oncology, University of Padova, and
3. Istituto di Ricerca Pediatrico Fondazione Città della Speranza, Padova, Italy;
4. Institute of Pathology, Hematopathology Section and Lymph Node Registry, Christian-Albrechts University, Kiel, Germany; and
5. Pathology Unit, Ospedale San Bortolo, Vicenza, Italy