Suspected azathioprine-induced hypersensitivity pneumonitis in a patient with autoimmune hepatitis: A rare case report.

Azathioprine (AZA) is a widely prescribed immunosuppressive agent in the long-term management of autoimmune hepatitis (AIH), valued for its steroid-sparing properties and efficacy in maintaining disease remission. While its common adverse effects - such as myelosuppression, hepatotoxicity, and gastrointestinal intolerance - are well-recognized and routinely monitored, hypersensitivity pneumonitis (HP) remains an exceptionally rare but potentially life-threatening complication. Herein, we describe a 21-year-old female patient with AIH diagnosed at age 18. Who developed possible AZA-induced HP during the 3rd year of continuous therapy. We discuss the potential immunopathogenic mechanisms, review the limited literature on AZA-related pulmonary toxicity, and emphasize the importance of early recognition to prevent irreversible lung injury and optimize patient outcomes.