5-Aminosalicylic Acid-Induced Liver Injury in a Patient with Ulcerative Colitis: A Case Report

Introduction: Drug-induced liver injury (DILI) associated with 5-aminosalicylic acid (5-ASA) is a rare but potentially life-threatening adverse event. Case Presentation: We report the case of a 58-year-old woman with ulcerative colitis who developed DILI after initiating maintenance therapy with the multimatrix system 5-ASA. The patient presented with grade 4 liver enzyme elevation on day 98 after initiating 5-ASA and was admitted to the hospital. Blood tests revealed the mixed liver injury, and imaging studies showed no abnormalities except for mild lymph node enlargement. Liver biopsy revealed acute lobular hepatitis with interfacial activity. The patient's score on the International Autoimmune Hepatitis Group 1999 revised scoring system was a total score of 10, causing a suspicion for the diagnosis of autoimmune hepatitis. The DDW-J 2004 scale calculated a total score of six, indicating a high probability of DILI. We suspected DILI due to 5-ASA, and the 5-ASA formulations were discontinued. The patient was treated with ursodeoxycholic acid and neominophagen C, and her liver function gradually improved without steroid treatment. Finally, we definitively diagnosed DILI based on the pathological findings and clinical course after discontinuation of 5-ASA. Conclusion: This case highlights the importance of monitoring liver function in patients receiving 5-ASA therapy.