Cytomegalovirus-induced severe enterocolitis associated with ANCA-associated vasculitis and diffuse alveolar haemorrhage in a child: a diagnostic and therapeutic dilemma

ANCA-associated vasculitis (AAV) is rare in children and may be triggered by infections. Cytomegalovirus (CMV), a common pathogen, can rarely cause severe gastrointestinal complications like stricture, obstruction, and perforation. While adult cases suggest a potential association between CMV and AAV, reports of severe intestinal complications leading to AAV in immunocompetent children are scarce. A previously healthy 12-year-old boy presented with fever, abdominal pain, and vomiting. Abdominal CT revealed intestinal obstruction and perforation. Emergency surgery confirmed acute hemorrhagic necrotizing enterocolitis, and metagenomic next-generation sequencing (mNGS) diagnosed CMV viremia. His condition deteriorated rapidly, culminating in acute respiratory failure and acute kidney injury requiring continuous renal replacement therapy. Serological testing using indirect immunofluorescence was positive for cytoplasmic-ANCA (C-ANCA). Confirmatory ELISA testing confirmed positivity for anti-proteinase 3 (PR3) antibodies at a titer of 1:51; anti-myeloperoxidase (MPO) antibodies were negative. Chest CT and bronchoscopy confirmed diffuse alveolar haemorrhage. AAV was diagnosed per the 2022 ACR/EULAR criteria. The central management challenge was the co-occurrence of active CMV infection and fulminant vasculitis. Immunosuppressive therapy was withheld until sepsis parameters normalized. A life-threatening bleeding event on day 13 prompted initiation of high-dose methylprednisolone and cyclophosphamide, leading to rapid clinical improvement. A subsequent renal biopsy showed subacute tubulointerstitial injury without crescents. Severe CMV enterocolitis may be temporally associated with fulminant AAV in children. In pediatric cases of severe CMV infection with multi-organ dysfunction, a high index of suspicion for AAV and ANCA serology testing is warranted. Furthermore, multidisciplinary team input is crucial for guiding optimal timing of immunosuppression in the context of concurrent active infection, which is pivotal for improving patient outcomes.