Pityriasis rosea is a fairly common skin condition which produces a rash. It can occur at any age, but is most commonly seen in those between 10 to 35 years of age. It a benign condition but can be distressing in some, causing itch and lasting for many weeks to months.
What Causes Pityriasis Rosea?
The exact cause of pityriasis rosea is not known. There is some evidence that it may be due to a viral infection.
What Are The Symptoms And Signs Of Pityriasis Rosea?
• Symptoms of a common cold or flu may precede up to about two-thirds of cases.
• A larger 2 to 10 cm oval reddish patch may “herald” the onset of the general rash of pityriasis rosea, hence the name “herald patch”. It is typically found on the abdomen, but may be found elsewhere as well.
• 1 to 2 weeks after the herald patch, patches of pink, oval-shaped, flaky rash appear over the torso and may extend to the proximal limbs, in a characteristic “Christmas-tree” distribution. The face is usually spared.
• In about 25% of cases, the rash is not itchy. In another 25%, there is severe itchy, and in the remaining 50%, the rash mildly to moderately itchy.
• The rash usually lasts 6 to 8 weeks, but may occasionally last for several months.
How Is Pityriasis Rosea Diagnosed?
The diagnosis of pityriasis rosea is made by careful examination of the rash and its distribution. If there is doubt about the diagnosis, you may require referral to a dermatologist to rule out other conditions such as ringworm (tinea), psoriasis, eczema, drug eruptions or other viral rashes. A skin biopsy may sometimes be required.
How is Pityrisis Rosea Treated?
No treatment is usually required as it generally spontaneously resolves in about 6 to 8 weeks.
In cases where itch is bothersome, antihistamines or topical steroids are sometimes prescribed. Exposing the rash to sunlight has been found to make it go away more quickly. As such, treatment with ultraviolet light (which is most useful only in the first week of eruption) has been used to hasten resolution.