Despina N Maritsi1, Panaguotis Krepis2, George Vartzelis3, Aggeliki Syggelou4, Maria Tsolia5. 1. Rheumatology Unit, Second Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, Medical School, National and Kapodistrian University of Athens (NKUA), Athens, Greece. dmaritsi@gmail.com. 2. Infectious Diseases Unit, Second Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, Medical School, National and Kapodistrian University of Athens (NKUA), Athens, Greece. 3. Rheumatology Unit, Second Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, Medical School, National and Kapodistrian University of Athens (NKUA), and Neurology Unit, Second Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, School of Medicine, National and Kapodistrian University of Athens (NKUA), Athens, Greece. 4. Rheumatology Unit, Second Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, Medical School, National and Kapodistrian University of Athens (NKUA), Athens, Greece. 5. Rheumatology Unit, Second Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, Medical School, National and Kapodistrian University of Athens (NKUA), and Infectious Diseases Unit, Second Department of Paediatrics, "P. & A. Kyriakou" Children's Hospital, Medical School, National and Kapodistrian University of Athens (NKUA), Athens, Greece.