Palmoplantar Pustulosis-like Eruption Induced by Baricitinib for Treatment of Rheumatoid Arthritis

OBJECTIVES: Baricitinib is an orally active Janus kinase (JAK) inhibitor used in the treatment of moderate to severe rheumatoid arthritis (RA). MATERIALS AND METHODS: Here, we report the case of a 56-year-old Caucasian male diagnosed with RA who developed palmoplantar pustulosis (PPP) while being treated with baricitinib. RESULTS: The patient’s PPP resolved after discontinuation of baricitinib and recurred when this was restarted. Based on causality assessment, it was considered a drug-induced PPP. CONCLUSION: To the authors’ knowledge, this is the first case of baricitinib-induced PPP. LEARNING POINTS: Baricitinib is a small, orally active molecule that inhibits JAK-1 and JAK-2, which is used in the treatment of rheumatoid arthritis. Baricitinib has been also used in the treatment of psoriasis, alopecia areata and atopic dermatitis. Palmoplantar pustulosis is a rare cutaneous side effect of baricitinib.