Pityriasis rosea most commonly occurs between ages 10 and 35. It affects women more often. The cause of pityriasis rosea may be viral infection (some research has implicated human herpesviruses 6, 7, and 8). Drugs may cause a pityriasis rosea–like reaction.
The condition classically begins with a single, primary, 2- to 10-cm herald patch that appears on the trunk or proximal limbs. A general centripetal eruption of 0.5- to 2-cm rose- or fawn-colored oval papules and plaques follows within 7 to 14 days. The lesions have a scaly, slightly raised border (collarette) and resemble ringworm (tinea corporis). Most patients itch, occasionally severely. Papules may dominate with little or no scaling in children and pregnant women. The rose or fawn color is not as evident in patients with darker skin; children more commonly have inverse pityriasis rosea (lesions in the axillae or groin that spread centrifugally).
Classically, lesions orient along skin lines, giving pityriasis rosea a Christmas tree–like distribution when multiple lesions appear on the back. A prodrome of malaise, headache, and sometimes arthralgia precedes the lesions in a minority of patients.
Diagnosis of pityriasis rosea is based on clinical appearance and distribution.
Differential diagnosis includes
Serologic testing for syphilis is indicated when the palms or soles are affected, when a herald patch is not seen, or when lesions occur in an unusual sequence or distribution.
No specific treatment is necessary because the eruption usually remits within 5 weeks and recurrence is rare.
Artificial or natural sunlight may hasten resolution.
Antipruritic therapy such as topical corticosteroids, oral antihistamines, or topical measures may be used as needed.
Some data suggest that acyclovir 800 mg orally 5 times a day for 7 days may be helpful in patients who present early and have widespread disease, or present with flu-like symptoms. Of note, pityriasis rosea during pregnancy (especially during the first 15 weeks of gestation) is associated with premature birth or fetal demise. Pregnant women should be offered acyclovir; however, antiviral therapy has not proved to reduce obstetric complications.
Pityriasis rosea is a self-limited, inflammatory disorder of the skin possibly caused by human herpesvirus types 6, 7, or 8 or drugs.
An initial 2- to 10-cm herald patch is followed by centripetal eruption of oval papules and plaques with a slightly raised and scaly border, typically appearing along skin lines.
Diagnose based on clinical appearance and distribution.
Treat with antipruritic drugs as needed and possibly topical corticosteroids and/or sunlight.
Pityriasis rosea during the first 15 weeks of pregnancy is associated with premature birth or fetal demise.
Pregnant women should be offered antiviral therapy, even though this has not proved to reduce obstetric complications.