When anti-tumor necrosis factor-α backfires: paradoxical psoriasis and psoriatic arthritis in a patient with hidradenitis suppurativa.

Dear Editor, Hidradenitis suppurativa (HS) is a chronic inflammatory disease of the folliculoapocrine units. Biological therapies, historically led by the anti-tumor necrosis factor (TNF)-α antibody adalimumab, have transformed severe HS management. Recently, interleukin (IL)-17 inhibitors (secukinumab, bimekizumab) were also approved in Europe for moderate-to-severe HS. However, TNF-α blockade can paradoxically induce or exacerbate inflammatory skin and joint conditions, including psoriasis (incidence 1-5%) and psoriatic arthritis. We report a case of paradoxical inverse psoriasis and suspected early psoriatic arthritis induced by adalimumab in an HS patient, successfully managed by switching to secukinumab. [...].