Juvenile pityriasis rubra pilaris
Juvenile pityriasis rubra pilaris (PRP) is an inflammatory disorder affecting cornification with onset in childhood. PRP is usually acquired, but there are heritable forms. It can present in 3 clinical forms: type III (classical), type IV (circumscribed), and type V (atypical). Overlap between these subtypes is common in children.
In classical / type III (10% of all cases), there is a fairly rapid onset of extensive, confluent, scaling, pink-orange plaques in association with keratoderma of the hands and feet. Age of onset may be at any time during childhood, with a peak around age 6. Half of all cases resolve without therapy in less than 6 months, although many take longer to resolve and 10%-20% may become chronic.
Circumscribed / type IV (25% of all cases) primarily involves the extensor knees and elbows with palmoplantar keratoderma. It is the most common pediatric subtype. Onset is most commonly at age 3-9 years. The rate of spontaneous resolution is similar to classical juvenile / type III PRP.
Atypical / type V (less than 5% of all cases) is present from birth or in the first few years of life. It may be inherited in an autosomal dominant pattern due to activating mutations in CARD14.
L44.0 – Pityriasis rubra pilaris
238620000 – Classical juvenile pityriasis rubra pilaris
Differential Diagnosis & Pitfalls
- Psoriasis is the closest clinical mimic of PRP. Psoriasis has a more adherent scale, and larger lesions do not have areas of normal skin within them.
- Keratosis pilaris is usually limited to the extensor extremities.
- Wong-type dermatomyositis – presents with features of both dermatomyositis and PRP
- Erythrokeratodermia variabilis
- Drug eruption
- Atopic dermatitis
- Contact dermatitis (irritant or allergic)
- Sézary syndrome (rare in children; see cutaneous T-cell lymphoma)
- Type V / atypical juvenile PRP can be confused with lamellar ichthyosis. Scleroderma-like changes of hands and feet may be rarely observed.
- CARD14-associated papulosquamous eruption (CAPE) can present with classical PRP-like features, psoriasis-like features, or atypical PRP-like features.