Norwegian Scabies in an Atopic Patient Under Dupilumab Treatment

PRÉCIS We present a case of Norwegian scabies in an atopic patient receiving dupilumab treatment. DISCUSSION A 23-year-old male patient with an autistic disorder, treated for severe atopic dermatitis with dupilumab 300 mg every 15 days for the last 4 months, revealed at the follow-up consultation a 2-week history of acute hyperkeratotic plaques and pruriginous vesicles. The flexures, the periumbilical region, and the hands were the most severely involved areas (Fig. 1). Before dupilumab treatment, he had no signs of hand dermatitis. In addition, his mother presented pruriginous interdigital vesicular lesions and reported pruritus in his father and in her 1 month before consultation.Figure 1: Hyperkeratotic plaques and pruriginous vesicles involving the hands.At the time of consultation, the simultaneous study of scale scraping in the patient and his mother revealed Sarcoptes scabiei under the microscope. Dupilumab was temporarily discontinued, and treatment with ivermectin 14 mg (scheduled on days 1, 2, 8, 9, and 15), concomitantly with topical applications of 5% permethrin and 5% salicylic acid in petrolatum, was established. Three weeks after the treatment, the patient was free of keratotic and vesicular lesions, and dupilumab could be restarted. The mother and father were treated with topical applications of 5% permethrin repeated 1 week later. Dupilumab blocks the activity of interleukin 4 (IL-4) and IL-13, 2 key cytokines of the helper T cell 2 immune response that are essential in fighting parasites.1 Although no data on a possible increase of Norwegian scabies with dupilumab therapy have been reported up to date, cases have been published in the context of other biological therapies that inhibit important cytokines of the helper T cell 2 route (anti–IL-23, anti–tumor necrosis factor).2–5 PEARL Norwegian scabies should be considered in any outbreak of new-onset pruritic dermatitis in dupilumab-treated patients.