PRP is initially characterized by skin lesions described as, sharply pointed, horn-like, brownish-red to rosy yellow- colored papules. These papules usually occur on the back of the wrists, the outside of the forearms, underarm folds, elbows, knees, backs of the hands, and fingers. When the papules grow and connect together they produce dry, scaly, rough, red plaques over large areas of the skin. Gray, brittle nails and excessive oiliness of the glands on the scalp (seborrhea) and face may also occur. Often the edges of the eyelids are turned outward (ectropion).
The specific underlying cause of PRP is unknown. Researchers indicate that the condition may be hereditary or acquired. In many patients, PRP appears to occur randomly for no known reason (sporadically). However, in some affected individuals, evidence suggests that the disorder may be inherited as an autosomal dominant trait. Human traits, including the classic genetic diseases, are the product of the interaction of two genes for that condition, one received from the father and one from the mother.
Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary to cause a particular disease. The abnormal gene can be inherited from either parent or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from an affected parent to an offspring is 50% for each pregnancy. The risk is the same for males and females. In some individuals, the disorder is due to a spontaneous (de novo) genetic mutation that occurs in the egg or sperm cell. In such situations, the disorder is not inherited from the parents.
Some researchers suggest that PRP may result from abnormalities in vitamin A metabolism. (Metabolism refers to the chemical processes occurring in the body.) However, such research has not been definitive, necessitating further investigation.
PRP is a rare disorder that may develop during childhood or adulthood. The condition appears to occur in males and females in relatively equal numbers. Reported cases include several affected individuals in a number of multigenerational families (kindreds) as well as isolated instances of the disorder.
PRP tends to follow a natural waxing and waning course, with episodes in which there is periodic worsening (exacerbation) or cessation (remission) of symptoms. As a result, according to many researchers, it may be difficult to evaluate the effectiveness of particular therapies. However, standard therapy for the condition typically includes treatment with vitamin A or synthetic vitamin A compounds (retinoids) administered topically or by mouth (orally). Synthetic retinoids prescribed for the treatment of PRP may include isotretinoin or etretinate. Low-dose methotrexate, an antineoplastic drug that is often used to fight abnormal cell proliferation, may be prescribed for some patients.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
For information about clinical trials sponsored by private sources, contact:
Harrison’s Principles of Internal Medicine, 14th Ed.: Anthony S. Fauci et al., Editors; McGraw-Hill Companies, Inc., 1998. P. 313.
Nelson Textbook of Pediatrics, 15th Ed.: Richard E. Behrman, Editor; W.B. Saunders Company, 1996. Pp. 1866-67.
Pityriasis Rubra Pilaris, Vitamin A and Retinol-Binding Protein: A Case Study: P.C. van Voorst Vader et al.; Acta Derm Venereol (1984; 64(5)). Pp. 430-32.
Childhood-Onset Pityriasis Rubra Pilaris with Immunologic Abnormalities. D. Shvili et al.; Pediatr Dermatol (May 1987; 4(1)). Pp. 21-23.
Isotretinoin Treatment of Pityriasis Rubra Pilaris. C.H. Dicken; J Am Acad Dermatol (Feb 1987; 16(2 Part 1)). Pp. 297-301.
Early Presentation of Pityriasis Rubra Pilaris. S.E. Caplan et al.; Cutis (Dec 1997; 60(6)). Pp. 291-96.
Adult Pityriasis Rubra Pilaris: A 10-Year Case Series. B.D. Clayton et al.; J Am Acad Dermatol (Jun 1997; 36(6 Pt 1)). Pp. 959-64.
Pityriasis Rubra Pilaris: A Retrospective Analysis of 43 Patients. K.B. Sorensen et al.; Acta Derm Venereol (Sep 1999; 79(5)). Pp. 405-06.
Pityriasis Rubra Pilaris. M.R. Albert et al.; Int J Dermatol (Jan 1999; 38(1)). Pp. 1-11.
FROM THE INTERNET
Online Mendelian Inheritance in Man (OMIM). Victor A. McKusick, Editor; Johns Hopkins University, Last Edit Date 6/13/95. Entry Number 173200.
The information in NORD’s Rare Disease Database is for educational purposes only and is not intended to replace the advice of a physician or other qualified medical professional.
The content of the website and databases of the National Organization for Rare Disorders (NORD) is copyrighted and may not be reproduced, copied, downloaded or disseminated, in any way, for any commercial or public purpose, without prior written authorization and approval from NORD. Individuals may print one hard copy of an individual disease for personal use, provided that content is unmodified and includes NORD’s copyright.
National Organization for Rare Disorders (NORD)
55 Kenosia Ave., Danbury CT 06810 • (203)744-0100