Organizing Pneumonia Secondary to Infliximab in a Pediatric Patient with Ulcerative Colitis

Background Organizing pneumonia (OP) is a rare interstitial lung disease characterized by intra-alveolar fibroblastic plugs and chronic inflammation. Although most cases are idiopathic, OP may occur secondary to infections, autoimmune disease, or drug exposure. Pulmonary complications of tumor necrosis factor-alpha (TNF-α) inhibitors are uncommon, and infliximab-associated OP is particularly rare in pediatrics. Case presentation A 12-year-old girl with ulcerative colitis (UC) on infliximab presented with three weeks of dyspnea, fever, and pleuritic chest pain. Computed tomography revealed bilateral peripheral infiltrates. Microbiologic testing and bronchoalveolar lavage were negative. Wedge biopsy demonstrated fibroblastic plugs (Masson bodies), consistent with OP. Infliximab was discontinued and mesalamine resumed. The patient’s symptoms improved without corticosteroids, with near-complete radiologic resolution at two months. Conclusions This case highlights infliximab-associated OP in a pediatric patient, highlighting a need for awareness of rare pulmonary toxicities from biologics. Importantly, resolution occurred without corticosteroids, suggesting that withdrawal of the offending agent may suffice in select cases.