The clinical pattern of a scaly herald patch predating the eruption of multiple scaly macules is the hallmark of pityriasis rosea (PR). This patient’s severe itching is also classic for PR.
PR’s etiology is believed to be a reactivation of infection from human herpes viruses 6 and 7.1 Prodromal viral symptoms of malaise, sore throat, myalgias, and fever are common.2 Along with the prodromal symptoms, there is often a several-centimeter herald patch that occurs on the trunk. It is often confused with eczema or tinea due to its erythema and scale. (Secondary syphilis is also in the differential.) Sometimes PR can be differentiated by the scale pattern being a collarette instead of diffuse. The diagnosis becomes clearer 1 to 2 weeks later with the onset of multiple small scaly macules across the trunk following the Langer’s skin lines. The course is self-limited but takes several weeks to months to resolve.
If severe, PR may be treated with acyclovir 800 mg orally 5 times daily for 5 days; this is the same regimen for treating varicella zoster (shingles).1,2 Estimated recurrence rates are 4% to 24%.1,3
At age 49 years, this woman was older than the average patient with PR, as the usual age range is 10 to 35 years.1 Her physician advised her that the outbreak might recur. She was also given a prescription for oral hydroxyzine 25 mg to be taken at bedtime if the itching was interfering with her sleep. Her physician told her to return for reevaluation if the rash did not resolve in 3 months. She did not return for reevaluation.
Photo and text courtesy of Daniel Stulberg, MD, FAAFP, Professor and Chair, Department of Family and Community Medicine, Western Michigan University Homer Stryker, MD School of Medicine, Kalamazoo.