Pityriasis rubra pilaris induced erythroderma

Pityriasis rubra pilaris (PRP) is a chronic papulosquamous disorder with characteristic skin lesions in the form of reddish-orange plaques, follicular keratoses, pityriasiform scaling, and palmoplantar keratoderma. The disease has six clinical subtypes. The more recognizable and common clinical subtypes (types 1 and 3) as well as HIV-associated PRP can progress into erythroderma within 2–3 months of onset. Patients presenting for the first time after erythroderma sets in can pose a diagnostic challenge. Distinctive clinical signs along with dermoscopy and histopathology can aid in the diagnosis. To date no standardized therapeutic approach has been established in PRP. Patients presenting acutely with erythroderma often need intensive care to cater to the loss of homeostasis. Systemic retinoids, methotrexate, and other immunosuppressives have been used with varying responses. Systemic retinoids remain the first line of therapy in most cases. Biologics are becoming increasingly popular to treat recalcitrant PRP. Ustekinumab may be considered in preference to tumor necrosis factor-α inhibitors in severe or erythrodermic PRP when acitretin and methotrexate have been ineffective or are contraindicated. In HIV-associated PRP, antiretroviral therapy may result in complete response. Acitretin can be added if indicated.