2025 Volume 37 Issue 2 Pages 103-111
We present two cases of patients with rheumatoid arthritis（RA）complicated with nontuberculous mycobacterium（NTM）. Case 1 was an 82-year-old woman who developed RA in 1994. Adalimumab was introduced in 2010, but it was ineffective. Etanercept（ETN, 25mg/week）was then introduced, but infections were frequent. In 2013, ETN was switched to abatacept（ABT）500mg（IV）. However, due to Mycobacterium（M）. avium infection, it was discontinued according to the pre-revised treatment guideline. Currently, intraarticular steroid injections are being administered into the knee joint.
Case 2 was a 68-year-old woman with RA. She was treated with methotrexate（MTX, 8mg/week）, but multiple abnormal shadows were detected by CT scan, so MTX was switched to iguratimod. In 2022, RA relapsed, and M. intracellulare was detected in gastric fluid. She was treated with ethambutol, clarithromycin, glucocorticoid and ABT（125mg/week）, and the disease activity was controlled, so steroid was discontinued. Until 2014, the use of biological disease-modifying antirheumatic drugs（bDMARDs）was contraindicated in patients with RA with NTM. But, in the revised version of the treatment guide 2014, it was permitted to use bDMARDs under certain conditions. The favorable outcome in case 2 was likely due to this revision.
