1. Department of Pathology, Hematopathology Section and Lymph Node Registry; Christian-Albrecht University Kiel and University Hospital Schleswig-Holstein; Campus Kiel Michaelisstr. 11 24105 Kiel Germany
2. Clinical Institute of Pathology; Medical University Vienna; Vienna Austria
3. Department of Pathology; Children's Hospital; Warsaw Poland
4. Department of Pathology and Department of Oncohematology; Federal Scientific and Clinical Centre of Pediatric Hematology, Oncology and Immunology; Moscow Russia
5. NHL-BFM Study Center and Department of Pediatric Hematology and Oncology; Justus-Liebig University; Giessen Germany
6. Department of Pediatric Hematology and Oncology; St. Anna Children's Hospital; Medical University; Vienna Austria
7. Division of Pediatric Hematology, Oncology and Stem Cell Transplantation; Department of Pediatrics; University Medical Center Aachen; Aachen Germany