Diagnosis is by clinical appearance and may be supported by biopsy. Differential diagnosis includes seborrheic dermatitis (in children) and psoriasis when disease occurs on the scalp, elbows, and knees.
Causes of Pityriasis Rubra Pilaris
What does it look like?
Classical adult-onset PRP most often starts on the head, neck and upper trunk as a red scaly rash. Often there is a solitary lesion but within a few weeks multiple patches appear and they join together to form groups of reddish-orange lesions. Over a few weeks these spread downwards and may cover most of the body (erythroderma). Rough, dry plugs can be felt within the patches and are due to plugged hair follicles, often most obvious on the backs of the fingers. Patients may also complain of itching in the early stages of the disease.
PRP most often starts as a patchy rash on the scalp, face or chest. Over a period as short a several weeks it extends downward, and often covers much of the body. It spares areas of old scars and injuries, and leaves small islands of entirely unaffected skin. The rash has an orange-red color ("salmon") and the palms and soles become thickened. Rough, dry plugs can be felt within the rash
Pityriasis Rubra Pilaris Treatment
Topical medications such as emollients may be used to relieve symptoms of dryness and cracking. In severe cases acitretin or isotretinoin may be useful. Methotrexate has been of limited value. The best treatment is Accutane or Soriatane pills. These are closely related "retinoid" medications. While these have many minor side effects, they do not usually cause any serious harm to the body. A more potent and more effective treatment is methotrexate tablets, but as these can have dangerous side effects they are saved for people who don't improve with the retinoids. Methotrexate may put the PRP into remission, so it goes away and stays away.
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