摘要
Pityriasis rubra pilaris (PRP), also known as pityriasis pilaris, is a rare chronic inflammatory skin disease characterized by cutaneous scaling erythematous and clusters of small follicular papules which can coalesce into red-orange scaly patches and have a similar appearance of psoriasis. Hyperkeratosis of the palms and soles may also be present in PRP patients. There is a lack of information in the study regarding the precise incidence rate or prevalence of PRP, but some scientists proposed an incidence of 1 case in 3500-50,000 patients consulting with a dermatologist. The etiology and pathogenesis of PRP remains unclear, although several hypotheses claim that genetic factor, vitamin A deficiency, dysfunction in keratinization, endocrine disturbance, infections, and autoimmune disease are associated with the pathogenesis of PRP, but further research is needed. PRP can be divided into six subtypes, according to its clinical features, age of onset and prognosis. The histopathology of PRP is characterized by epidermal hyperkeratosis, follicular plugging, "checkerboard" pattern of parakeratosis, mild irregular acanthosis, and liquefaction degeneration of basal cells. Although there is no medication approved by the US Food and Drug Administration (FDA), most practitioners recommend combination therapy which consists of topical agents (such as emollients, keratolytic agents etc.), and systemic agents (such as oral retinoid) as the first-line treatment for PRP.