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AT-A-GLANCE
Common self-limited papulosquamous eruption typically lasting 5 to 8 weeks.
Occurs worldwide in all races and age groups, with peak incidence between the ages of 10 and 35 years.
Classically begins as an isolated 3- to 5-cm oval plaque on the trunk with a collarette of fine scale just inside the periphery, which plaque is called a herald patch.
This is followed by a secondary eruption of similar appearing but smaller lesions on the trunk and proximal extremities, usually with their long axis along the lines of cleavage.
Many atypical variants exist in contrast to the pattern described above.
Pityriasis rosea can have associated systemic symptoms and pruritus, but many cases are asymptomatic.
Etiology is unknown, but it is thought to be a viral exanthem most likely related to infection or reactivation of human herpesvirus (HHV)-6 and/or HHV-7.
Usually only supportive treatment and reassurance is needed, but for severe cases acyclovir may hasten recovery and lessen symptoms.
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In 1860, Gibert first used the term pityriasis rosea (PR), meaning pink (rosea) scales (pityriasis).1 PR is most common in teenagers and young adults, and is likely a viral exanthema currently thought to be related to primary infection or reactivation of human herpesvirus (HHV)-6 (HHV-6) and/or HHV-7.2-6 PR is fairly common, self-limited, and not associated with long-term sequelae. It classically begins as an isolated 3- to 5-cm oval plaque on the trunk with a collarette of fine scale just inside the periphery, which plaque is called a herald patch. This lesion is then followed by a secondary eruption of similar appearing but smaller lesions most prominently on the trunk and proximal extremities, usually with their long axis along the lines of cleavage in what is often described as a “Christmas tree” pattern. However, there are many atypical presentations of the herald patch distribution, secondary eruption morphology, and overall rash distribution. PR is commonly asymptomatic, but pruritus and systemic flu-like symptoms may be present. Often only supportive treatment and patient education are needed for management, but in cases with a widespread eruption, severe pruritus, or significant systemic symptoms acyclovir may be beneficial.
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PR has a worldwide distribution and is found in all races. One institution in the United States found the incidence to be 0.16% (~160 cases per 100,000 person-years).7 Studies in other countries report incidences ranging from 0.75% to 1.17%.8,9 A recent publication combined many of the PR epidemiologic studies from around the world and reported an incidence of 0.64 per 100 dermatologic patients.10 In some studies PR was found to be more common in colder months,7,9 but other studies show no significant seasonal variation.2,11 Studies have demonstrated clustering of cases supporting the hypothesis of an infectious etiology.12,13 There is a slight female preponderance at 1.39:1.10 The peak incidence of PR occurs ...