Pityriasis rosea is a medical condition characterized by a rash that extends out from the middle of the body in a pattern resembling drooping tree branches. The rash typically starts with a large oval or circular herald patch on the abdomen, chest, or back that can measure several inches in diameter. The initial herald patch is followed by multiple smaller spots that create a branch-like pattern.
Although the condition affects individuals of all ages, it is most often seen in children and adults between 10 and 35 years of age. Medical dermatology experts have not determined the exact cause of pityriasis rosea; however, it may be associated with a viral infection. Most cases of pityriasis rosea resolve without treatment within 10 weeks. The condition is not believed to be contagious.
The first sign of the condition is a raised, scaly herald patch. Additional scaly spots may develop a few days to weeks following the initial herald patch. Some patients experience fatigue, fever, or a sore throat shortly before the herald patch appears.
The rash may cause severe itching or leave dark spots on the skin even after the rash has cleared.
The appearance and unique presentation of the rash are usually sufficient for a doctor to make a diagnosis. In some instances, the doctor may scrape a small sample of cells from the rash to rule out ringworm, which can have a similar appearance.
Although the rash typically resolves spontaneously within a few weeks, patients should see a board-certified dermatologist for appropriate treatment, especially if the rash is bothersome. Corticosteroids, antiviral drugs, and antihistamines may be used to alleviate symptoms and shorten the duration of the rash. The rash may fade with exposure to artificial or natural sunlight; however, light therapy may also cause dark spots that can remain even after the rash resolves.
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