Successful Treatment of Pityriasis Rubra Pilaris with Risankizumab in Children.

Pityriasis rubra pilaris (PRP) is a rare inflammatory skin disease that affects men and women of all ages, including children. PRP is characterized by follicular and palmoplantar hyperkeratosis and salmon-colored scaling plaques. The exact pathogenesis of PRP is still unknown; most PRP cases are acquired, but some cases may show a familial occurrence, often associated with a mutation in the CARD14 gene. Due to the rarity of PRP, treatment recommendations are based mainly on case reports, small case series and expert opinions and still represent a major therapeutic challenge, especially in children. A growing number of reports on treatment with biologicals, particularly anti-TNFα, has been published. However, an involvement of the IL-23/Th17 axis in both psoriasis and PRP pathogenesis may suggest that this pathway may be a potential therapeutic target. Here, we present three pediatric patients with PRP successfully treated with risankizumab. All patients exhibited a severe course of PRP and lack of response to conventional therapy, including acitretin, cyclosporine and phototherapy. A single dose of 75 mg risankizumab resulted in almost complete clearance of skin lesions in case 1 and 2 at week 4. In patient 3, clear skin was achieved after the second administration of risankizumab (150 mg). All patients continue the treatment with risankizumab, and no adverse effects have been reported up to the present time. Our study demonstrates that risankizumab, an IL-23 blocker, shows good efficacy and safety among pediatric patients with PRP.