NSAID-Induced Acute Interstitial Nephritis Concurrent With IgA Vasculitis: A Case-Based Systematic Review.

Overlap between acute interstitial nephritis (AIN) and glomerulonephritis is uncommon and diagnostically challenging. We present the first pediatric case of clinically diagnosed immunoglobulin A vasculitis nephritis (IgAV-N) concurrent with nonsteroidal anti-inflammatory drug (NSAID)-induced AIN. A 14-year-old boy was hospitalized for recurrent gastroenteritis, purpura, and arthralgia treated with ibuprofen. After 5 days, he developed stage 3 acute kidney injury, subnephrotic proteinuria, hypertension, and oligoanuria. Kidney biopsy showed mild to moderate interstitial inflammation with tubulitis; immunofluorescence was negative for glomerular IgA, with nonspecific tubular C3 staining. After NSAID discontinuation, 10 dialysis sessions, and corticosteroids, kidney function recovered completely within 3 months. To support the clinical lesson highlighted by our case, we conducted a systematic review of biopsy-confirmed AIN-glomerulonephritis overlap. PubMed, Scopus, Web of Science, and Google Scholar were searched for biopsy-confirmed AIN with concurrent glomerulonephritis. Clinical features, etiologies, treatments, and outcomes were extracted. Systematic review identified 8 studies (12 patients). Drug-related AIN predominated (9 of 12), followed by infection (2 of 12) and autoimmune disease (1 of 12). Nephrotic-range proteinuria was described in 6, hematuria in 8, and hypersensitivity findings in 7 of the 12 patients. Complete recovery occurred in 7 and partial recovery in 3 patients, and dialysis was required in 2 of the 12 patients. NSAID-induced AIN concurrent with IgA vasculitis nephritis should be suspected in atypical acute kidney injury.