Definition of Pityriasis Rosea

Pityriasis Rosea is a common skin rash in which an outbreak of lesions occurs and resolves over a period of 3 to 12 weeks, generally without treatment or complications.

The lesions are characteristically oval with distinct borders and may be smooth (macules), raised (papules), or scaly (plaques). Often the lesions itch and sometimes they cause the skin to be hypersensitive to touch. Doctors believe a virus causes pityriasis rosea.

Symptom and Diagnostic Path

The primary symptom of pityriasis rosea is an itchy (pruritic) rash that appears on the back, chest, arms, and legs. There is usually an initial outbreak, called a herald lesion, with subsequent eruptions of lesions in other locations. Often the dermatologist will biopsy a lesion to confirm the diagnosis, as well as conduct blood tests to rule out secondary syphilis, which has a rash very similar to that of pityriasis rosea.

Pityriasis rosea is very similar in appearance to the rash that occurs with secondary syphilis. As untreated syphilis has serious health consequences, the diagnostic path should include a blood test to rule out syphilis.

Treatment Options and Outlook

Treatment aims to relieve symptoms. Cool baths and skin moisturizers often are enough to relieve mild pityriasis rosea. Topical and oral antihistamine medications, and sometimes mild corticosteroid medications, are necessary to control itching. The lesions clear up on their own after about 8 weeks, though in some people the rash and itching may persist for up to 12 weeks.

Risk Factors and Preventive Measures

Doctors do not know what causes pityriasis though strongly suspect a virus. Outbreaks tend to occur among people who are in close proximity, commonly during the winter months. Complications are very uncommon though scratching can open the lesions and allow secondary infection to develop. Pityriasis rosea is a self-limiting condition so recovery is without residual effects.


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