By Gary M. White, MD

Photodistributed erythema multiforme Note the urticarial lesions one day after the woman wore a bikini at the beach. Notice how lesions favor sun-exposed skin and not under the bikini.

Photodistributed erythema multiforme (EM) differs from most other photodermatoses in that it may occur without any increased/significant exposure to UV light. In fact, herpes reactivation (e.g., cold sore) and drug exposure are the most common triggers.


Urticarial papules and plaques develop rapidly in the sun-exposed areas. Small vesicles or even bulla may be present. The entire face, the sides and back of the neck, and outer arms are typical. In women, the buttocks and thighs may be involved if there has been significant sun exposure there in the past. Recurrent attacks are common.


Young men are typically affected. The herpes outbreak precedes the skin eruption by approximately 7 to 10 days. In one case, the lesions were limited to areas previously affected by sunburn.


Reported drugs include phenylbutazone, triclocarban, afloqualone, bufexamac, paclitaxel, simvastatin, pravastatin, paroxetine, and naproxen.


Patients with PEM associated with PMLE typically had recurrent PMLE for years and then developed a second type of eruption that was clinically compatible with EM but occurred 1 to 2 weeks after the episode of PMLE.


Additional Pictures

Young man with photo EM precipitated by a cold sore 7 days prior. Rash was on the arms, face, and neck (here). Small vesicles were present.
Photodistributed erythema multiforme Photodistributed erythema multiforme

Everywhere but under the bikini in this young woman.
Photodistributed erythema multiforme Photodistributed erythema multiforme Photodistributed erythema multiforme


Note the striking resemblance of the woman's buttocks in this link to the one above. Actas Dermosifiliogr. 2013;104:645-53


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