Pityriasis Rosea

Pityriasis rosea (PR) is a well known skin disorder that has a classic presentation. The initial skin lesion usually presents as a "herald patch" followed by a distinct generalized skin rash. The secondary skin rash almost always appears within 7-14 days after the initial "herald patch".

Most rashes last about 3-6 weeks. The herald patch is not seen in all individuals and about 20% of the individuals do not report such a patch. The secondary rash usually presents in crops and follows the cleavage lines of the skin. Often this is referred to as a "Christmas tree" pattern rash

PR occurs with equal frequency in both genders and has been reported world wide. It is a harmless skin rash and usually resolves on its own in most cases

The rash can last from several weeks to several months. In the majority of cases, the rash resolves without any consequences.

The rash is most common between the 2nd and 4th decade of life but can occur in children.


PR can present with other symptoms besides the rash which include:

- general malaise

- nausea

- fever

- joint pains

- headache

- itching which may be intense and seen in more than 70% of individuals

The herald patch is usually obvious and can be of any size but usually circular and about the size of a fist or larger. It almost always appears "salmon" colored with a dark peripheral zone. The rash is most common on the back or chest but can appear on the neck or extremities.

The secondary rash is always symmetrical and localized and may involve the chest, abdomen or extremities. A scaly ring may surround the secondary rash. The zig zag rash may appear like a "Christmas tree" pattern. The secondary rash can occur anywhere but is most common on the neck, truck and extremities.

In some dark skinned individuals, PR usually causes skin discoloration when it has resolved.

Rarely PR may appear in the mouth and present as an ulcer

Many individuals claim that the skin rash is more obvious during hot weather or exercise.


PR has not identifiable cause but does appear in the spring and autumn months.

Certain drugs have been associated with PR but the correlation is not strict. The involved drugs include:

- barbiturates

- D penicillamine

- Metronidazole

- Isotretinoin

- Captopril

- Gold


Individuals who develop PR also have a strong history of atopic dermatitis, acne and seborrhea.

The diagnosis of PR is usually made from clinical exam and its presentation. There are not laboratory tests to make a diagnosis. To confirm the diagnosis a skin biopsy is sometimes done

Pityriasis rosea is not infectious and most individuals just develop one episode during their lifetime.

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