Adalimumab-Induced Paradoxical Psoriasis Treated with Biologics Targeting the IL-17/IL-23 Axis in Patients with Hidradenitis Suppurativa.

BACKGROUND: Paradoxical psoriasis (PP) has been mainly described in patients receiving tumor necrosis factor-α (TNFα) inhibitors for inflammatory bowel disease or psoriasis vulgaris, while such data in the context of hidradenitis suppurativa (HS) are scarce. The purpose of this study was to demonstrate the course of PP and the underlying HS upon switching from adalimumab to a biologic agent targeting the interleukin (IL)-17/IL-23 axis. METHODS: The electronic medical database of the outpatient department for HS of a tertiary hospital for skin diseases was searched to identify patients with moderate-to-severe HS under treatment with adalimumab, who developed PP and were switched to biological therapy with an IL-17 or IL-23 inhibitor between February 2016 and January 2022. Disease assessment scores were evaluated at baseline, at time of PP development, as well as six and 12 months thereafter. RESULTS: Among the 83 patients who received adalimumab for the treatment of HS between February 2016 and January 2022, 10 patients (12%) developed paradoxical psoriasiform skin reactions after a median time of seven (range, 2-48) months. There were four females (40%) and six males (60%) with a median age of 42.5 (range, 33-56) years. Five patients presented with plaque psoriasis and five with palmoplantar pustulosis, while four had intertriginous and three nail involvement. In most of the patients, HS responded well to adalimumab at onset of PP. Eight patients were changed to secukinumab, one to ustekinumab, and one to risankizumab. HS further improved in all but 2 patients, one receiving secukinumab and one receiving risankizumab. In addition, all patients achieved improvement of PP. CONCLUSION: Despite the small number of patients, this study provides support that patients with adalimumab-induced PP may benefit from biologics targeting the IL-17/IL-23 axis. Further studies are needed to establish the optimal therapeutic strategy of the anti-TNFα-induced PP in the context of HS.

Development of New Lesions of Hidradenitis Suppurativa on a Caesarean Section Scar: A Manifestation of the Koebner Phenomenon?

Hidradenitis suppurativa (HS) is a chronic, inflammatory, recurrent skin disorder of the hair follicle. Trauma, mechanical pressure, or friction could have an important role in the pathogenesis of HS. We present a patient with HS who developed new HS lesions shortly after a cesarean section, which could be explained by the Koebner phenomenon. Koebnerization in HS has recently been observed in patients in whom new lesions developed at an ectopic location free from apocrine glands as a result of trauma. More studies need to be conducted to shed light on the possible relation between HS and surgical trauma. Avoidance of external trauma could be included in general measures of HS treatment.