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Polymorphous light eruption in Adult
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Polymorphous light eruption in Adult

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Contributors: Jeffrey M. Cohen MD, Belinda Tan MD, PhD, Susan Burgin MD
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Polymorphous light eruption (PMLE), or polymorphic light eruption, is a common acquired cutaneous disorder that is characterized by a pathological response to ultraviolet radiation (UVR). Erythematous papules, vesicles, and plaques (hence the name "polymorphous") develop minutes to hours after exposure to UVR, such as sunlight or a tanning bed. The eruption is often pruritic. It is nonscarring and photodistributed. Systemic symptoms such as fever, malaise, headache, myalgias, and arthralgias are usually absent. While lesions can last up to several weeks, most resolve within several days.

PMLE is most commonly seen in women with lighter skin phototypes aged 20-30, but it can occur in either sex, all ages, and all ethnicities. Attacks most commonly occur during the spring and early summer months, especially after the first sun exposure of the season, and disappear during the winter.

The etiology of PMLE is not well understood. One theory is that UVR modifies antigens in the skin of PMLE patients to make them immunogenic. There are also data to suggest that PMLE involves a type IV delayed-type hypersensitivity reaction. The action spectrum for PMLE is UVA in most cases, but UVB and both UVA and UVB may also incite the response.

Although the condition frequently recurs, the tendency toward the development of PMLE and the severity of the eruption diminish with repeated sunlight exposure. This phenomenon is termed "hardening." As the summer proceeds, it has been observed that the incidence of new eruptions decreases. Prophylactic phototherapy supports this concept of hardening or tolerance.

Despite the variability of presentations, individual patients tend to experience the same clinical manifestations with each episode.


L56.4 – Polymorphous light eruption

367484009 – Polymorphous light eruption

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Last Reviewed: 05/01/2017
Last Updated: 06/12/2017
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Polymorphous light eruption in Adult
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Polymorphous light eruption : Erythema, Pruritus, Sun-exposed distribution, Smooth papules
Clinical image of Polymorphous light eruption
Multiple erythematous papules and papulovesicles on the dorsal hand and forearm.
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