Systemic Polyarteritis Nodosa in the Young: A Single‐Center Experience Over Thirty‐Two Years

Objective. Polyarteritis nodosa (PAN) is a rare disease of childhood. The aims of this study were to describe the clinical features, treatment, and outcome of systemic childhood PAN and to identify predictors of relapse. Methods. A single-center retrospective medical records review of children with PAN fulfilling the European League Against Rheumatism (EULAR)/Paediatric Rheumatology European Society (PRES)/Paediatric Rheumatology International Trials Organisation (PRINTO) classification criteria who were seen over a 32-year period was performed. Data on demographic and clinical features, treatments, relapses (recurrence of clinical signs/symptoms or occurrence of new symptoms after initial remission requiring escalation or resumption of immunosuppressive therapy), and deaths were recorded. A disease activity score was retrospectively assigned using the Paediatric Vasculitis Activity Score (PVAS) instrument. Cox regression analysis was used to identify significant predictors of relapse. Results. Sixty-nine children with PAN were identified; 55% were male, and their median age was 8.5 years (range 0.9–15.8 years). Their clinical features at presentation were fever (87%), myalgia (83%), skin (88%), renal (19%), severe gastrointestinal (GI) (10%), and neurologic (10%) involvement. The PVAS at presentation was 9 of 63 (range 4–24). Histopathologic analysis of the skin showed necrotizing vasculitis in biopsy samples from 40 of 50 children. Results of selective visceral arteriography suggested the presence of PAN in 96% of patients. Treatment included cyclophosphamide and corticosteroids (83%), plasma exchange (9%), and biologic agents (after 2002; 13%). The relapse rate was 35%, and the mortality rate was 4%. Severe GI involvement was associated with increased risk of relapse (P 0.031), while longer time to induce remission (P 0.022) and increased cumulative dose of cyclophosphamide (P 0.005) were associated with lower relapse risk. Conclusion. Childhood PAN is a severe inflammatory disease of insidious onset and variable clinical presentation. Relapses occurred more frequently in those with severe GI involvement. A higher cumulative dose of cyclophosphamide was associated with a lower risk of relapse.