Pityriasis Rosea

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Medical Author:

Gary W. Cole, MD, FAAD

Gary W. Cole, MD, FAAD

Dr. Cole is board certified in dermatology. He obtained his BA degree in bacteriology, his MA degree in microbiology, and his MD at the University of California, Los Angeles. He trained in dermatology at the University of Oregon, where he completed his residency.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

William C. Shiel Jr., MD, FACP, FACR

Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

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• Pityriasis rosea begins as a single, large pink patch found on the trunk called the "herald patch."
• The herald patch is followed one to two weeks later with smaller pink patches in a "Christmas tree" formation.
• Pityriasis rosea is generally asymptomatic except for the appearance.
• Pityriasis rosea is mildly itchy in 50% of cases and clears spontaneously in an average of six to eight weeks.
• Pityriasis rosea is sometimes accompanied by mild, flu-like symptoms and may mimic fungal infection and other conditions.
• Pityriasis rosea has no long-lasting health effects and is not directly contagious.
• Lifelong immunity occurs after one episode of pityriasis rosea.

Pityriasis rosea is a common rash usually seen in individuals between 10 to 35 years of age. The rash typically lasts six to eight weeks, rarely extending 12 weeks or longer. Once a person has pityriasis rosea, it generally does not recur in their lifetime.

Pityriasis rosea characteristically begins as an asymptomatic single, large pink, scaly patch called the "herald patch" or mother patch, measuring 2-10 centimeters. The herald patch is a dry, pink to red patch which appears on the back, chest, or neck and has a well-defined, scaly border.

One to two weeks following the initial appearance of the herald patch, a person will then develop many smaller pink patches across their trunk, arms, and legs. The second stage of pityriasis rosea erupts with a large number of oval spots, ranging in diameter from 0.5 centimeter (size of a pencil eraser) to 1.5 centimeters (size of a peanut). The individual spots form a symmetrical "Christmas tree" pattern on the back with the long axis of the ovals oriented in the "Lines of Blaschko" (invisible skin lines of embryonic origin). This rash is usually limited to the trunk, arms, and legs, rarely occurring on the face and neck. Pityriasis rosea generally spares the face, hands, and feet.