A Case of Adalimumab-Induced Psoriasiform Dermatitis in an Ankylosing Spondylitis Patient: Unusual Progression after Adalimumab Retreatment.

Dear Editor: A 34-year-old Korean man having Ankylosing spondylitis (AS) presented with a 1-month history of lesions on his entire body. We received the patient’s consent form about publishing all photographic materials. Numerous erythematous papules, pustules, and papulosquamous plaques on approximately 25% of the body surface area (Fig. 1). He had been treated with infliximab bimonthly after 2005 for AS, but infliximab had been switched to adalimumab two months before, due to loss of efficacy. After switch, skin eruption aggravated even after application of topical corticosteroid. Results of laboratory examinations were mostly normal. The results of his histopathological examination are shown in Fig. 2. Thick hyperkeratosis, confluent parakeratosis, and elongated rete ridges accompanied by focal spongiosis and exocytosis at the epidermis were noted. Superficial perivascular lymphohistiocytic infiltration was observed in the dermis. Based on clinical manifestations and histopathological findings, adalimumab-induced psoriasiform dermatitis was diagnosed. Clinical progress is summarized in Supplementary Fig. 1. Adalimumab was halted,