2nd July 2023

Pityriasis Rosea

Aetiology and Symptoms

Pityriasis rosea is a common condition in teenagers and young adults, however, it can occur at any age. It is a self-limiting rash that tends to resolve in 6-10 weeks. The presenting feature is often a circular or oval ‘herald patch’ which is typically seen on the chest, abdomen or back, before a generalised rash occurs. The patch is raised, salmon-pink or red and 2-5cm in diameter. There is often a peripheral scale trailing just inside the edge of the lesion.

The exact cause is not well understood, but it is suggested that it can occur following viral (HHV-6/7) and bacterial infections, vaccinations, and drug-induced reactions (there are many associated drugs such as ACEi, NSAIDs, imatinib, metronidazole and isotretinoin, to name a few).

Most patients have no systemic symptoms when the rash occurs. However, mild-severe itching can occur in up to 25% of patients. It is a clinical diagnosis that can be supported with histological tests.

Treatments

It is a self-limiting condition. Management focuses on reducing pruritus in the 25% of patients who have severe itching. This can be done with emollients, non-scented soap substitutes and cautious sun exposure. Other treatments that may help reduce the duration of symptoms include topical steroid creams, oral steroids in severe cases and antivirals such as aciclovir. UVB therapy has been shown to be most effective at decreasing the duration of the rash that patients experience.