Primary vasculitides that affect children are a challenging and complex group of disorders that may involve any system of the body and lead to significant morbidity and mortality. In recent years, there have been significant advances in the field of childhood vasculitides, including the development of classification criteria and outcome assessment. Although some forms of vasculitis occur in both children and adults, considerable differences exist between childhood and adult vasculitides; we review childhood vasculitides, thus highlighting their differences with the adult forms of the disease. We will also discuss monogenic forms of vasculitis, such as deficiency of adenosine deaminase type 2 (DADA2) and haploinsufficiency of A20 (HA20). (C) 2018 Elsevier Ltd. All rights reserved.