Pityriasis rubra pilaris

Definition

Pityriasis rubra pilaris (PRP) refers to a group of skin conditions that cause constant inflammation and scaling of the skin.

Cause

• In the vast majority of people with PRP, the cause is unknown.
• Most cases are thought to result from a combination of unknown genetic factors and environmental triggers.
• Rarely, PRP is due to changes (mutations) in a gene called CARD14.

Gene mutations

• Mutations in this gene are found particularly in people with PRP type V.
• This gene gives the body instructions for making a protein involved in regulating the body's immune responses and inflammatory reactions.
• While the protein is present in many of the body’s tissues, it is found in great amounts in the skin.
• Mutations in this gene are thought to trigger an abnormal inflammatory response, leading to the signs and symptoms of PRP.

Types

There are several types of PRP classified by age when symptoms begin, body areas involved, and whether other conditions are present. This condition occurs in adults (adult onset PRP) as well as children (juvenile onset PRP).

• Type I (classic adult type), the most common type, goes away on its own within 3 years in about 80% of people. After it goes away, relapses are uncommon.
• Type II (atypical adult type) can last for a very long time, sometimes more than 20 years.
• Type III (classic juvenile type) usually goes away within one year. Rarely, this type persists for a longer period of time.
• Type IV (circumscribed juvenile) may be associated with alternating periods of getting better and worse. About one-third of people with this type have improvement with age.
• Type V (atypical juvenile type) is usually chronic.
• Type VI (HIV-associated) tends to be resistant to most treatments.

Inheritance

• In most cases, PRP is not inherited and the cause is not known.
• In some people, particularly some with type V (the “atypical juvenile type”), PRP has autosomal dominant inheritance and may be caused by mutations in the CARD14 gene.

Signs and symptoms

• Features of this condition vary greatly from person to person.
• Signs and symptoms often get worse over time and may affect the skin, nails, mucous membranes, and eyes.

Signs and symptoms may include:

• Redness and scaling of the skin and scalp, which often develops into itchy, orange-red plaques.
• Plaques may first occur on only some parts of the body, but may eventually spread over the whole body.
• The elbows, knees, ankles, hands and feet are most commonly affected.
• Thickening of the skin on the palms and soles (palmoplantar keratoderma).
• Thickening, discoloration, or shedding of the nails.
• Thinning of the hair.
• Plaques and irritation in the mouth.
• Dryness of the eyes and/or ectropion (outward turning of the eyelid).
• Reduced quality of life associated with persistent pain, itching, or sleep disturbances.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Erythroderma
• Irregular hyperpigmentation
• Palmoplantar keratoderma(Thickening of palms and soles)
• Papule

30%-79% of people have these symptoms

• Pruritus(Itching)
• Subungual hyperkeratosis(Thickened, discolored skin under nail)

5%-29% of people have these symptoms

• Abnormal oral cavity morphology(Abnormality of the oral cavity)
• Ectropion(Eyelid turned out)
• Eczema
• Ichthyosis
• Lichenification
• Neoplasm
• Pustule(Pimple)

Diagnosis

Molecular genetics tests may include:

• Sequence analysis of the entire coding region
• Deletion/duplication analysis
• Targeted variant analysis

Treatment

• PRP can be difficult to treat and many treatment options have been tried.
• There is little information on which treatments are best because none have been studied in large clinical trials.
• Treatment options may vary based on the symptoms in each person but often involve a combination of medicines taken internally and applied topically to the skin.
• Topical therapy options may include corticosteroids, keratolytics, calcipotriol, tretinoin, and tazarotene.
• For people with mild PRP, using one or more of these may be enough to control symptoms.
• Most people with PRP also need additional medicines to control their symptoms, especially if the condition affects a large part of the body.
• Oral retinoids are usually tried first.
• Examples include acitretin and isotretinoin .
• Methotrexate, an immune system suppressant, may be tried when oral retinoids are not safe for a particular person, or when they have stopped working.
• Other immune system suppressants that have been helpful in some case reports include cyclosporine and azathioprine.
• Biologic therapies may be another option, based on limited data.
• Examples include various biologic TNF-alpha inhibitors and ustekinumab.

Prognosis

• PRP may go away on its own, have periods of remission (when symptoms improve or go away), improve over time, or it may be chronic (long-lasting).
• In some cases, the condition goes away and then returns (relapses) after therapy is stopped.
• PRP can significantly affect quality of life, especially if there is ongoing pain, itching, or sleep problems. People with PRP have a normal life expectancy.

NIH genetic and rare disease info

• NIH info on Pityriasis rubra pilaris

Pityriasis rubra pilaris is a rare disease.

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