11.16 Pityriasis Rosea
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agk's Library of Common Simple Emergencies

Presentation
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Patients with this benign disorder often seek 
acute medical help because of the worrisome 
sudden spread of a rash that began with one local 
skin lesion. This "herald patch" may develop 
anywhere on the body and appears as a round 2-6 
cm mildly erythematous scaling plaque. There is 
no change for a period of several days to two 
weeks; then the rash appears, composed of small 
(l-2cm), pale, salmon-colored, oval macules or 
plaques with a coarse surface surrounded by a rim 
of fine scales. The distribution is truncal with 
the long axis of the oval lesions running in the 
planes of cleavage of the skin (parallel to the 
ribs). The condition may be asymptomatic or 
accompanied by varying degrees of pruritis and, 
occasionally mild malaise. The lesions will 
gradually extend in size and may become confluent 
with one another. The rash persists for 6-8 weeks 
then completely disappears. Recurrences are 
uncommon.

What to do:
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- Reassure the patient about the benign nature of 
    this disease. Be sympathetic and let him know 
    that you understand how frightening it can 
    seem.
- Draw blood for serologic testing for syphilis 
    (e.g., VDRL). Secondary syphilis can mimic 
    pityriasis rosea. Make a note to track down 
    the results of the test.
- Provide relief from pruritis by prescribing 
    hydroxyzine (Atarax) 50mg q6h or an emollient 
    such as Lubriderm. Tepid corn starch baths (1 
    cup in 1/2 tub of water) may also be 
    comforting.
- Inform the patient that he should anticipate a 
    6-8 week course of the disease, but to seek 
    followup care if the rash does not resolve 
    within 12 weeks.

What not to do:
---------------

- Do not use topical or systemic steroids. These 
    are only effective in the most severe 
    inflammatory varieties of this syndrome.
- Do not send off a serologic test for syphilis 
    without assuring the results will be seen and 
    acted upon.

Discussion
----------

Pityriasis rosea is seen most commonly in 
adolescents and young adults during the spring 
and fall seasons. It is probably a viral 
syndrome. The "herald patch" may not be seen in 
20-30% of the cases and there are many variations 
from the classic presentation described. Other 
diagnostic considerations besides syphilis 
include tinea corporis, seborrheic dermatitis, 
acute psoriasis, and tinea versicolor.

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 from Buttaravoli & Stair: COMMON SIMPLE EMERGENCIES
 Longwood Information LLC 4822 Quebec St NW Wash DC
 1.202.237.0971 fax 1.202.244.8393 electra@clark.net
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