1 Childhood & Adolescent Hematology Oncology Unit, 2nd Paediatric Department, Faculty of Health Sciences, Aristotle University of Thessaloniki, AHEPA Hospital, Thessaloniki, Greece.
2 Department of Paediatrics, Paediatric Hematology/Oncology Unit, Democritus University of Thrace Faculty of Medicine, Alexandroupolis, Thrace, Greece.