Pityriasis rosea
| Pityriasis rosea | |
|---|---|
 |
|
| Pityriasis rosea on human back and front | |
| Classification and external resources | |
| Specialty | Dermatology, infectious disease |
| ICD-10 | L42 |
| ICD-9-CM | 696.3 |
| DiseasesDB | 24698 |
| MedlinePlus | 000871 |
| eMedicine | derm/335 emerg/426 ped/1815 |
| Patient UK | Pityriasis rosea |
| MeSH | D017515 |
Pityriasis rosea (also known as pityriasis rosea Gibert) is a skin rash. It is benign but may inflict substantial discomfort in certain cases. Classically, it begins with a single "herald patch" lesion, followed in 1 or 2 weeks by a generalized body rash lasting up to 12 weeks, however usually around 6 - 8.
The symptoms of this condition include:
The cause of pityriasis rosea is not certain, but its clinical presentation and immunologic reactions suggest a viral infection as a cause. Some believe it to be a reactivation of herpes viruses 6 and 7, which cause roseola in infants.
Experienced practitioners may make the diagnosis clinically. If the diagnosis is in doubt, tests may be performed to rule out similar conditions such as Lyme disease, ringworm, guttate psoriasis, nummular or discoid eczema, drug eruptions, other viral exanthems. A biopsy of the lesions will show extravasated erythrocytes within dermal papillae and dyskeratotic cells within the dermis.
A set of validated diagnostic criteria for pityriasis rosea is as follows:
A patient is diagnosed as having pityriasis rosea if:
The essential clinical features are the following:
The optional clinical features are the following:
The exclusional clinical features are the following:
The condition usually resolves on its own, and treatment is not required. Oral antihistamines or topical steroids may be used to decrease itching. 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, scratching should be avoided. It's possible that scratching can make itching worse and an itch-scratch cycle may develop with regular scratching (that is, you itch more because you scratch, so you scratch more because you itch, and so on). Irritants such as soaps with fragrances, hot water, wool, and synthetic fabrics should be avoided. Lotions that help stop or prevent itching may also be helpful.
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Wikipedia