Late-Onset Mesalazine-Induced Eosinophilic Pneumonitis Presenting as Non-Resolving Pneumonia: A Diagnostic Pitfall in...

Area of Science:

• Pulmonology
• Gastroenterology
• Pharmacology

Background:

• Mesalazine is a common treatment for ulcerative colitis.
• While generally safe, mesalazine can rarely cause eosinophilic pneumonitis, a serious drug-induced lung injury.
• This condition often presents with symptoms similar to respiratory infections.

Purpose of the Study:

• To report a case of mesalazine-induced eosinophilic pneumonitis in a patient with ulcerative colitis.
• To highlight that this adverse reaction can occur after prolonged, stable mesalazine therapy.
• To emphasize the importance of considering mesalazine as a potential cause of unexplained respiratory symptoms in ulcerative colitis patients.

Main Methods:

• A case report of a 24-year-old male with ulcerative colitis.
• Clinical presentation included progressive dyspnea and non-resolving pulmonary infiltrates despite antibiotic treatment.
• Diagnostic workup revealed peripheral eosinophilia and characteristic CT imaging findings.

Main Results:

• The patient presented with symptoms suggestive of a respiratory infection that did not resolve with antibiotics.
• Investigations confirmed peripheral eosinophilia and bilateral subpleural ground-glass opacities on CT scan.
• Discontinuation of mesalazine and initiation of corticosteroid therapy led to rapid clinical and radiological improvement.

Conclusions:

• Mesalazine-induced eosinophilic pneumonitis is a rare but significant adverse effect of ulcerative colitis treatment.
• Pulmonary toxicity from mesalazine can manifest even after extended periods of uneventful therapy.
• Clinicians should maintain a high index of suspicion for mesalazine-induced eosinophilic pneumonitis in ulcerative colitis patients with unexplained respiratory symptoms.