A 25-year-old man was admitted to our institution for remission induction therapy to treat a 12-year condition of ulcerative colitis (UC). Previously, he was treated with drugs, such as mesalamine, immunomodulators, prednisolone (PSL), and anti-TNFα anti-body, but remission was not maintained. Therefore, we started remission induction therapy with 20 mg/day of tofacitinib (TOF) to inhibit the action of Janus kinase. On the 29th day after TOF administration, he developed a lung abscess with high fever. A chronic bulla was already present in his lung; therefore, the lung abscess was likely formed due to a combination of the bulla being present and the pharmacological effects of TOF. Our report is significant as it highlights the compounding association between TOF and PSL therapy and bulla presence with the rare adverse effect of developing an abscess.
