Pityriasis Rosea

Pityriasis Rosea

Dr Christophe HSU – dermatologist. Geneva, Switzerland

What is pityriasis rosea?

• Pityriasis rosea is a kind of “skin flu”. It might also be caused by a virus.
• It is more common in young adults.
• It tends to have seasonal peaks.

What does it look like?

• It is characterized clinically:

1. initially, it presents as a red circular lesion with a peripheral collarette of scaling. It is called the “herald” patch. The lesion can be located anywhere, but more often it is located on the chest, upper arms and the legs.
2. after, smaller lesions appear on the whole body except the face (in its typical presentation). The lesions on the back give rise to a “Christmas Tree” pattern.
3. The lesions are sometimes itchy, but most of the time they do not cause any symptoms.

   

   Pityriasis Rosea

Do other skin conditions look like pityriasis rosea?

• Because pityriasis rosea in its atypical presentation can sometimes look like secondary stage syphilis, blood tests are then needed to exclude it.

Does pityriasis rosea need to be treated?

• The condition heals on its own after around three months. To predict its disappearance, it is easier to remember the rule of the three 4’s:

1. during 4 weeks, the lesions keep appearing (appearing phase)
2. during 4 weeks, the number of lesions appearing is equal to the lesions disappearing (stabilisation phase)
3. during 4 weeks the number of lesions goes down (regression phase)

• In case of itching, the dermatologist may prescribe a steroid cream or a treatment with light (phototherapy).

Contributors

Dr Christophe Hsu – dermatologist. Geneva, Switzerland

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