Cutaneous eruption after commencing baricitinib for rheumatoid arthritis

Abstract

This case report describes a 64‐year‐old physician with seronegative rheumatoid arthritis (RA) who was treated with baricitinib after failing multiple other therapies. Within 3 weeks, he developed a nonpruritic cutaneous reaction, including a symmetric acneiform folliculitis and a papulosquamous dermatosis. Biopsy results indicated a perivascular and interface drug eruption associated. Although Janus kinase (JAK) inhibitors, such as baricitinib, have a good safety profile, skin reactions have been reported in a small number of cases. The mechanism underlying these reactions is not fully understood, but it is believed to involve an imbalance between anti‐inflammatory and proinflammatory cytokines. This case emphasises the importance of careful monitoring of patients for skin reactions when initiating treatment with JAK inhibitors and the need for further research in this area.