54 Eosinophilic Pneumonitis Induced by Infliximab in an Elderly Patient With Ulcerative Colitis

Introduction: Pulmonary manifestations in individuals with inflammatory bowel disease (IBD) are considered rare. There are some reports of interstitial lung disease, such as eosinophilic pneumonia (EP), related to the use of certain medications employed in the conventional treatment of IBD, and more recent reports have described an association with infliximab, a tumor necrosis factor (TNF) inhibitor. Here, we present a case of an elderly patient with ulcerative colitis, without a prior diagnosis of lung disease, who developed a respiratory condition consistent with EP after 12 months of infliximab therapy. Case Description/Methods: A 69-year-old man was diagnosed with ulcerative colitis (pancolitis) in 2020 and was initially treated with oral mesalamine and azathioprine. In March 2022, he experienced a disease flare, with colonoscopy showing moderate activity (Mayo score 2). Azathioprine was discontinued due to hepatotoxicity. Vedolizumab was initiated in November 2022 and optimized in March 2023, with no significant therapeutic response (primary non-responder). In August 2023, infliximab was started and optimized in May 2024, resulting in adequate clinical response and disease control. Twelve months after starting infliximab, he developed a dry cough, mainly at night, with gradual worsening, associated with dyspnea on mild exertion and significant weight loss, requiring hospitalization. He presented desaturation in room air, peripheral blood eosinophilia (15%), spirometry showing a mild restrictive defect, and bronchoalveolar lavage with 1% eosinophils. Chest CT in September 2024 revealed bilateral basal reticular opacities, mild architectural distortion, bronchovascular traction, and scattered ground-glass opacities, suggestive of interstitial lung disease. In October 2024, a basal pulmonary segmentectomy was performed, and histopathology demonstrated chronic interstitial inflammation with an organizing pneumonia pattern and eosinophilic infiltrates; fungal staining (Grocott) was negative. Chest radiographs obtained in 2021 and 2023, prior to biological therapy, were normal, suggesting a temporal association between infliximab use and the development of interstitial lung disease. Following confirmation of the diagnosis, infliximab was discontinued (last dose July 2024). Dyspnea was controlled with long-acting beta2-adrenergic agonists, with stabilization of pulmonary function. Ustekinumab was requested as the next therapeutic option for ulcerative colitis. Discussion: In the literature, cases of EP in individuals with IBD have been reported shortly after the first infusion as well as after multiple infliximab infusions. The interval between infliximab infusion and the onset of respiratory symptoms does not seem to follow a defined pattern. Its pathogenesis is not well established; however, it is believed to represent a hypersensitivity reaction related to the drug. The diagnosis of this condition involves respiratory symptoms, blood gas analysis abnormalities, spirometry changes, bronchoalveolar lavage with eosinophilia, imaging studies (chest computed tomography), and, if necessary, lung biopsy showing eosinophilic infiltrate. Conditions such as tuberculosis reactivation, aspergillosis, and bacterial infections must be ruled out. Treatment consists of oxygen therapy and hospitalization, if required. Corticosteroid therapy should be initiated along with discontinuation of infliximab, and, preferably, introduction of another drug class. Considering the risk of respiratory involvement even after multiple infliximab infusions in individuals with IBD, continuous monitoring of respiratory symptoms and thorough investigation are essential for the proper management of this rare complication.