A case report of interstitial pneumonia induced by vedolizumab in a patient with ulcerative colitis.

RATIONALE: The interstitial pneumonia (IP) linked to vedolizumab (VDZ) in patients with ulcerative colitis (UC) is rare. Prompt diagnosis and treatment can improve patient outcomes. PATIENT CONCERNS: A 39-year-old man with UC who received VDZ as sole therapy developed symptoms such as chest tightness, cough, and suffocation. DIAGNOSES: IP was confirmed through pulmonary function tests, chest computed tomography, and bronchoscopic biopsy. INTERVENTIONS: The patient was given methylprednisolone and VDZ cessation. OUTCOMES: The patient's symptoms improved and remained symptom-free after nearly 2 years. LESSONS: VDZ-induced IP should be considered when evaluating pulmonary infections in UC patients treated with VDZ.