Post-Infectious Bronchiolitis Obliterans as a Model of Immune-Mediated Airway Fibrosis: A Pediatric Case Report

Post-infectious bronchiolitis obliterans (PIBO) is a rare but severe chronic lung disease of childhood, characterized by irreversible small-airway obstruction following severe lower respiratory tract infections early in life. The disease course is often progressive and associated with long-term respiratory morbidity, while effective disease-modifying therapies remain limited. We report the case of a young child who developed severe PIBO following adenovirus pneumonia complicated by prolonged respiratory failure and multisystem involvement. Diagnosis was based on persistent respiratory symptoms, characteristic radiologic findings, and poor response to conventional anti-inflammatory treatment. Given the severity of the clinical course and steroid-refractory disease, an individualized immunomodulatory strategy, including hydroxychloroquine, was initiated within a multidisciplinary framework. During follow-up, the patient showed progressive clinical improvement, with gradual weaning from continuous oxygen supplementation, fewer respiratory exacerbations, simplification of systemic therapies, and radiologic findings consistent with partial improvement. Although causal conclusions regarding treatment efficacy cannot be drawn from a single case, the overall disease trajectory appeared more favorable than typically reported in PIBO cohorts. This case supports the emerging view of PIBO as an immune-mediated airway fibrotic disorder and underscores the importance of integrating detailed clinical phenotyping with evolving molecular insights to inform future precision medicine in pediatric post-infectious airway disease.