Pityriasis rosea: Wikis

  

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Pityriasis rosea
Classification and external resources

An oval rash of Pityriasis Rosea
ICD-10 L42.
ICD-9 696.3
DiseasesDB 24698
MedlinePlus 000871
eMedicine derm/335 emerg/426 ped/1815
MeSH D017515

Pityriasis rosea is an acute, benign, self-limiting skin rash. Classically, it begins with a single "herald patch" lesion, followed in 1 or 2 weeks by a generalized body rash lasting about 6 weeks.[1][2][3] Its etiology is unknown, though it is thought to involve viral infection. It is generally non-contagious,[4][5] though there have been reports of small epidemics in fraternity houses and military bases.[3]

Contents

Symptoms

The symptoms of this condition include:

  • An upper respiratory tract infection may precede all other symptoms in as many as 68.8% of patients[6]
  • A single, 2- to 10-cm oval red "herald" patch appears, classically on the abdomen.[7][3] Occasionally, the "herald" patch may occur in a 'hidden' position (in the armpit, for example) and not be noticed immediately. The "herald" patch may also appear as a cluster of smaller oval spots, and be mistaken for acne. Rarely, it does not become present at all.[7]
  • 7-14 days after the herald patch, large patches of pink or red, flaky, oval-shaped rash appear on the torso.[7] In 6% of cases an inverse distribution may occur, with rash mostly on the extremities.[8] The more numerous oval patches generally spread widely across the chest first, following the rib-line in a characteristic "christmas-tree" distribution.[7] Small, circular patches may appear on the back and neck several days later. It is unusual for lesions to form on the face, but they may appear on the cheeks or at the hairline.
  • About one-in-four people with PR suffer from mild to severe symptomatic itching. (Moderate itching due to skin over-dryness is much more common, especially if soap is used to cleanse the affected areas.) The itching is often non-specific, and worsens if scratched. This tends to fade as the rash develops and does not usually last through the entire course of the disease.[7]
  • The rash may be accompanied by low-grade headache, fever, nausea and fatigue. Over-the-counter medications can help manage these.[7]

Diagnosis

Herald lesion of PR (second lesion above the ankle, approximately in the center of the plate) depicted 21 days after initial encounter. The patient had an episode of sore throat, that was treated with a strong antibiotic without success. The lesion appeared approximately one week after the end of the upper respiratory tract infection.

Experienced doctors may make the diagnosis clinically.[3] If the diagnosis is in doubt, tests may be performed to rule out similar conditions such as ringworm, guttate psoriasis, nummular or discoid eczema, drug eruptions, other viral exanthems,[3] and especially secondary syphilis.[9] A biopsy of the lesions will show extravasated erythrocytes within dermal papillae and dyskeratotic cells within the dermis.[3]

Treatment

No treatment is usually required.

Oral antihistamines or topical steroids may be used to decrease itching.[3] Steroids do provide relief from itching, and improve the appearance of the rash, but they also cause the new skin that forms (after the rash subsides) to take longer to match the surrounding skin color. While no scarring has been found to be associated with the rash, itching and scratching should be avoided. Irritants such as soap should be avoided, too; a soap containing moisturizers (such as goat's milk) may be used, however, any generic moisturizer can help to manage over-dryness.[citation needed]

Direct sunlight makes the lesions resolve more quickly.[3] According to this principle, medical treatment with ultraviolet light has been used to hasten resolution,[10] though studies disagree whether it decreases itching[10] or not.[11] UV therapy is most beneficial in the first week of the eruption.[10]

Prognosis

In most patients, the condition lasts only a matter of weeks; in some cases it can last longer (up to six months). The disease resolves completely without long-term effects. Two percent of patients have recurrence.[12][13]

Epidemiology

The overall prevalence of PR in the United States has been estimated to be 0.13% in men and 0.14% in women. It most commonly occurs between the ages of 10 and 35.[3] It is more common in winter.[3]

See also

References

  1. ^ Freedberg; et al (2003), Fitzpatrick's Dermatology in General Medicine (6th ed.), McGraw-Hill, p. 445, ISBN 0071380760 
  2. ^ James, William; Berger, Timothy; Elston, Dirk (2005). Andrews' Diseases of the Skin: Clinical Dermatology (10th ed.). Saunders. pp. 208-9. ISBN 0721629210. 
  3. ^ a b c d e f g h i j Habif, Thomas P (2004), Clinical Dermatology: A Clinical Guide to Diagnosis and Therapy (4th ed.), Mosby, pp. 246-8, ISBN 0-323-01319-8 
  4. ^ "Pityriasis rosea". DERMAdoctor.com. http://www.dermadoctor.com/article_Pityriasis-Rosea_60.html. Retrieved 26 Jan 2010. 
  5. ^ "Pityriasis rosea". American Osteopathic College of Dermatology. http://www.aocd.org/skin/dermatologic_diseases/pityriasis_rosea.html. Retrieved 26 Jan 2010. 
  6. ^ Sharma, P (2000). J Am Acad Dermatol 42 (2 pt 1): 241. 
  7. ^ a b c d e f "Pityriasis rosea". American Academy of Dermatology. 2000, 2003. http://www.aad.org/public/publications/pamphlets/common_pityriasis.html. Retrieved 2009-06-04. 
  8. ^ Tay, Y; Goh, C (829). "One-year review of pityriasis rosea at the National Skin Centre, Singapore". Ann Acad Med Singapore 28 (6). 
  9. ^ Horn T, Kazakis A (1987). "Pityriasis rosea and the need for a serologic test for syphilis". Cutis 39: 81. 
  10. ^ a b c Arndt, KA (1983). "Treatment of pityriasis rosea with UV radiation". Arch Dermatol 119: 381. 
  11. ^ Leenutaphong V, Jiamton S (1995). "UVB phototherapy for pityriasis rosea: a bilateral compatison study". J Am Acad Dermatol 33 (6): 996. 
  12. ^ Kempf, W; et al (1999). "Pityriasis rosea is not associated with Human herpesvirus 7". Arch Dermatol 135 (9): 1070. 
  13. ^ Chuang, T-Y; et al (1982). "Pityriasis rosea in Rochester, Minnesota, 1969 to 1978: a 10-year epidemiologic study". J Am Acad Dermatol 7: 80. 

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