Upadacitinibで治療された反応性関節炎の進行性寛解

Reactive arthritis (ReA) is a postinfectious inflammatory disorder that may be difficult to treat in refractory cases. We describe a 20-year-old man with HLA-B27-positive ReA presenting with arthritis, conjunctivitis, balanitis, and psoriasiform skin lesions. Conventional therapies, including antibiotics, nonsteroidal anti-inflammatory drugs, corticosteroids, and sulfasalazine, failed to control disease activity. Treatment with upadacitinib (15 mg/day), a selective Janus kinase 1 inhibitor (JAK1), led to rapid improvement of joint, ocular, and cutaneous manifestations within three weeks. Corticosteroids were tapered and discontinued without relapse, and reduced-dose upadacitinib maintained remission for more than three months. This case highlights the potential role of JAK1 inhibition in ReA pathogenesis and suggests upadacitinib as a promising therapeutic option for refractory disease.