Abstract / Summary
Antithyroid drug (ATD)-induced ANCA-associated vasculitis (AAV) is a well-recognized complication in adults, but pediatric data remain scarce. This study characterizes the clinical spectrum, management, and outcomes of pediatric ATD-induced AAV. We report a case of a 13-year-old girl with Graves’ disease (GD) who developed propylthiouracil (PTU)-induced microscopic polyangiitis (MPA) presenting with diffuse alveolar hemorrhage (DAH). A systematic review of PubMed (through September 2026) and Chinese databases (CNKI, Wanfang) was conducted to identify all published pediatric ATD-induced AAV cases (age ≤ 18 years). Clinical features, treatment strategies, and outcomes were extracted and analyzed. Our patient presented with DAH, heavy proteinuria (peak spot urinary protein-to-creatinine ratio [UPCR] 2,018.6 mg/g), dual myeloperoxidase (MPO)/proteinase 3 (PR3)-ANCA positivity, and persistent disease activity despite PTU withdrawal—requiring methylprednisolone pulse therapy and 7 cycles of cyclophosphamide (cumulative 164.7 mg/kg), and ultimately ¹³¹I ablation for definitive GD treatment. At 18-month follow-up, DAH and proteinuria had completely resolved; MPO-ANCA remained positive despite sustained clinical remission, while PR3-ANCA had normalized. The systematic review identified 37 published studies reporting 53 published pediatric cases; with the addition of the present index case, the combined descriptive dataset comprised 54 pediatric cases (1994–2026; 85.2% female; mean age 13.0 years, range 7–18). Renal involvement was most common (74.1%), followed by cutaneous (42.6%) and pulmonary (37.0%). Definitive GD treatment with ¹³¹I during active AAV was reported in only 2 pediatric cases (one of which is the present index case). Complete remission was achieved in 32 (59.3%), partial remission in 18 (33.3%, including one patient progressing to end-stage renal disease), 3 patients died (5.6%), and the outcome was unknown (lost to follow-up) in 1 patient (1.9%). Dual ANCA positivity was present in 13.0% of cases, and serological-activity dissociation was observed in long-term follow-up. Pediatric ATD-induced AAV may remain active after drug withdrawal, consistent with autonomous autoimmunity, although this inference rests on limited observational evidence. Severe presentations such as DAH warrant aggressive immunosuppression; ¹³¹I may represent a feasible definitive treatment option in selected patients. Persistent ANCA positivity after clinical remission is consistent with serological-activity dissociation. Not applicable.