What is pityriasis rosea (a skin condition characterized by a rash)?

From the Research

Pityriasis rosea is a common, self-limiting skin rash that typically begins with a single, larger "herald patch" followed by smaller, oval-shaped, salmon-colored patches that often form a Christmas tree pattern on the trunk, and the most recent evidence suggests that it is primarily caused by human herpesvirus (HHV)-6 and HHV-7 1.

Description of Pityriasis Rosea

The condition most commonly affects young adults, typically between 10 and 35 years of age, with a peak during adolescence 1.

• The herald patch is an erythematous lesion with an elevated border and depressed center, and it is the most common presenting sign, found in approximately 80% of patients 1.
• A generalized, bilateral, symmetrical eruption develops in approximately 4 to 14 days and continues to erupt in crops over the next 12 to 21 days 1.
• Typical lesions are 0.5 to 1 cm, oval or elliptical, dull pink or salmon-colored macules with a delicate collarette of scales at the periphery 1.
• The long axes tend to be oriented along the skin lines of cleavage (Langer lines) 1.
• Lesions on the back may have a characteristic "Christmas tree", whereas lesions on the upper chest may have a V-shaped pattern 1.

Treatment and Management

The typical course is 6 to 8 weeks, and in the vast majority of cases, reassurance and symptomatic treatment should suffice 1.

• No specific medication is required for treatment, though topical corticosteroids like hydrocortisone cream (1%) applied twice daily can help relieve itching 2.
• Oral antihistamines such as loratadine (10mg daily) may also reduce itching 2.
• For severe cases, short courses of oral corticosteroids or UVB phototherapy might be considered 2.
• Active intervention may be considered for individuals with severe or recurrent pityriasis rosea and pregnant women with the disease, and treatment options include acyclovir, macrolides (in particular, erythromycin), and ultraviolet phototherapy 1.
• There is evidence supporting the use of oral acyclovir to shorten the duration of illness 1.

Prevention and Recurrence

Pityriasis rosea is not contagious, and recurrence is rare 1.

• Patients should avoid harsh soaps, take lukewarm showers, and use moisturizers to minimize discomfort while waiting for the condition to resolve naturally 2.
• The exact cause remains unknown, but it's believed to be triggered by a viral infection, possibly human herpesvirus 6 or 7 1.