Introduction
Pityriasis rubra pilaris (PRP) is a rare familial and acquired papulosquamous disease. It is characterized by salmon-colored plaques with islands of sparing and palmoplantar hyperkeratosis. This condition can affect both adults and the pediatric population. 1Usually, it has a cephalocaudal progression, and the palms and soles show a waxy yellow-orange keratoderma. 1 PRP’s pathogenesis is not well understood. Still, there is evidence of increased expression of the interleukin IL-12/IL-23 and IL-17 axes in the affected skin. 2 There are various reported associations with PRP, including infections, autoimmunity, drugs, and malignancies. Still, more research is needed to understand these connections thoroughly.2 In familial cases, a specific gene mutation called CARD14 has been identified. 2 The incidence and prevalence of PRP are still unknown, but it is estimated to affect about 1 case per 400,000 of the population. 3 It tends to occur most commonly in the first and fifth decades of life affecting both men and women of all races equally. 4 The histopathologic characteristics of PRP are variable, however, it sometimes resembles psoriasis in its presentation. 5PRP is classified into six subgroups based on the age of onset, disease severity, prognosis, and other associated characteristics.6 The subgroups: III (classical juvenile), IV (circumscribed juvenile), and V (atypical juvenile) most commonly affect children. 6 About 10%, 25%, and 5% of PRP patients, respectively, are classified in these subtypes. 7
The course of the disease is variable; while some cases resolve spontaneously, others may be very challenging to treat.1 There are no official recommendations, therefore management is largely based on previous case reports. Topical corticosteroids, retinoids, and vitamin D analogs are often used as first-line therapy. 3,8 There is insufficient data regarding pediatric patients. 9 Furthermore, there is resistance to systemic therapy in children, however, it has been tried for refractory cases in adults. 10 While oral retinoids are considered the first choice as a systemic treatment, using high-dose acitretin for a long time in children carries an increased risk of side effects. 11 Currently, other systemic therapies including immunosuppressants and biologics are used for the treatment of juvenile PRP. 9 Here we present an infantile case of type III PRP successfully treated with cyclosporine A (CsA). Additionally, the use of CsA in juvenile-onset PRP is reviewed.