ANCA-associated vasculitides-lessons from the adult literature.

Anti-neutrophil cytoplasmic antigen antibody (ANCA)-associated disease is a rare manifestation of primary systemic vasculitis in paediatric patients but one that carries significant morbidity, potential long-term disability and early mortality. It therefore requires a high index of suspicion, targeted investigation, prompt treatment and long-term follow-up with specialist input at every stage. The well-recognised diversity and overlap in clinical, laboratory and histopathological features of the ANCA-associated systemic vasculitides continue to hamper accurate diagnosis, confounding epidemiological data and necessitating a blanket approach to treatment, which is largely extrapolated from studies in adult patients and carries significant side-effects. Herein we summarise current knowledge of the epidemiology, pathogenesis, principal manifestations, investigation and evidence-based management, extrapolated from adult studies, of these disorders. We also discuss recent efforts towards classification of the childhood vasculitides that emphasise the value of histological diagnosis. Progress in our understanding of the pathophysiology underlying ANCA-associated disease should lead to targeted, safer and more effective therapies for these conditions. Nonetheless, many questions remain outstanding, and academic paediatricians face real challenges in identifying and collating the few cases they encounter into study cohorts. Meeting this challenge will require international collaboration, not only among paediatricians but also with the specialists taking over care of these patients as they reach adulthood.