Pediatric ANCA-Associated Vasculitis: Variable Clinical Course in a Case Series of Three Patients and Literature Review

Background: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) represents a group of rare systemic autoimmune disorders marked by inflammation and damage to small- and medium-sized blood vessels. The clinical presentation of AAV is highly variable, ranging from isolated organ involvement to severe, life-threatening multisystem disease, posing significant challenges in diagnosis, treatment, and prognosis. Objective: To demonstrate the clinical heterogeneity and different outcomes in three pediatric cases of ANCA-positive disease and emphasize the importance of integrating clinical findings with laboratory and imaging investigations for accurate diagnosis. Methods: We present three pediatric patients (ages 12–15 years) with ANCA-positive results but distinct clinical presentations, evaluated at the Children’s Emergency Hospital “Louis Turcanu”, Timisoara, between 2020 and 2024. All cases were investigated according to EULAR/PRINTO/PReS criteria for pediatric vasculitis. Results: Case 1 (PR3-ANCA positive) developed severe multi-organ involvement, including granulomatosis with polyangiitis (GPA) with pulmonary hemorrhage, pericarditis, thrombotic events, and renal impairment, requiring intensive immunosuppression with cyclophosphamide, rituximab, and mycophenolate mofetil, ultimately developing chronic kidney disease stage 3a. Case 2 (BPI-ANCA positive) presented with purpuric lesions and painless joint swelling, responding favorably to corticosteroid therapy with subsequent remission. Case 3 (MPO-ANCA) manifested as polyarticular arthritis without other organ involvement and was ultimately diagnosed as seronegative juvenile idiopathic arthritis (JIA), achieving complete remission with adalimumab therapy. Conclusions: This case series highlights the diverse clinical and biological features of ANCA-positive conditions in children, emphasizing that ANCA positivity requires careful clinical correlation as it may indicate true vasculitis requiring aggressive treatment or alternative diagnoses such as JIA with incidental ANCA positivity. Tailored therapeutic strategies based on clinical presentation and continued research are essential to improve patient outcomes.