A case paradoxical hidradenitis suppurativa with janus kinase inhibitor, literature review and pooled analysis of biological agent‐induced <scp>HS</scp>

Hidradenitis suppurativa (HS) is a debilitating chronic inflammatory skin disease. Biological therapy has revolutionized it's the treatment. Paradoxical HS occur with various biological and targeted agents. We report a patient with juvenile rheumatoid arthritis who developed HS after 6 months of tofacitinib therapy. A comprehensive literature review identified 43 cases of paradoxical HS among patients on biological and targeted agents. Pooled analysis of the cases showed Crohn's disease 18(41.8%) and RA 9(20.9%) as commonest indications for biological therapy. Adalimumab 20(46.5%) followed by infliximab 9(20.9%) were the commonest offending agents. Duration of biological treatment prior to HS manifestation was 12(1-120) months. Smoking 21(48.8%) and overweight or obese 20(46.5%) were most frequent HS risk factors. Fourteen (32.6%) patients had a second paradoxical event, 11(25.6%) developed psoriasis and 4(9.3%) Crohn's disease. Presence of ≥1 risk factor for HS, continuation of the implicated biological agent and occurrence of more than one paradoxical event were factors associated with poor paradoxical HS outcome.