Mesalazine-induced Hypersensitivity Pneumonitis.

A 57-year-old woman with Crohn's disease (ulcerative proctitis) treated with mesalazine (5-ASA) developed worsening respiratory distress and cough. The lack of response to antibiotics and the results of bronchoalveolar lavage led to the diagnosis of mesalazine-related hypersensitivity pneumonitis, an infrequent entity. Symptoms improved after discontinuation of mesalazine and the administration of corticosteroid therapy. The authors discuss the diagnosis and management of this rare condition. LEARNING POINTS: A diagnosis of mesalazine-related hypersensitivity pneumonitis should be considered when unexplained respiratory symptoms develop during treatment with mesalazine.It is important to distinguish pulmonary manifestations in patients with inflammatory bowel disease secondary to drug-related toxicity from the disease process itself.Amelioration of symptoms and improvement in imaging and lung function seem to occur only upon abrupt discontinuation of the drug; severe symptoms such as respiratory failure may justify corticosteroid therapy. © EFIM 2021.