Infliximab-Induced Non-specific Interstitial Pneumonitis in a Patient With Ulcerative Colitis (UC).

Infliximab belongs to the family of tumor necrosis factor (TNF) alpha inhibitors and since its development, it has revolutionized treatment for both rheumatological diseases and inflammatory bowel disease (IBD). In IBD specifically, it has shown to result in symptomatic, endoscopic, and histological remission which is why it is one of the most widely used treatments for moderate to severe IBD. While common side effects include infections due to immunosuppression, cytopenias and hepatotoxicity, interstitial lung disease (ILD) has been infrequently reported to result from inflixiamb use. We present the case of a patient with ulcerative colitis (UC) who achieved remission with infliximab, however, after about two years of infusions, developed evidence of non-specific interstitial pneumonitis (NSIP). Extensive work up was done to rule out infections, mixed connective tissue disorders, and hypersensitivity pneumonitis. Although lung biopsy remains the gold standard for diagnosing NSIP; clinical, laboratory, and radiographic findings were sufficient in establishing this diagnosis. Initiation of empiric high dose steroids, and cessation of infliximab infusions showed improvement in respiratory status and resolution of lung findings. This case highlights the importance of recognizing adverse effects of infliximab on the pulmonary status of an IBD patient given that infliximab mediated ILD does not adhere to a specific timeline. Considering that respiratory function may be compromised post any number of infusions, it is imperative to acknowledge patients' respiratory complaints and initiate prompt investigation and evaluation for this rare complication.