Which physical findings are characteristic of polymorphous light eruption (PMLE)?

Updated: Jan 22, 2020
  • Author: Saud A Alobaida, MBBS, FRCPC; Chief Editor: Dirk M Elston, MD  more...
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Answer

As the name implies, clinical manifestations of polymorphous light eruption (PMLE) vary. Many different morphologies may appear on sun-exposed areas, but usually only one morphology dominates in a given individual.

Papules (most common), plaques, papulovesicles, and eczematous and erythema multiforme–like lesions are the most common morphologies. Photosensitive erythema multiforme and erythema multiforme–like PMLE can be difficult to distinguish clinically. Combined morphological types of lesions, while uncommon, do occur. For example, the small papular variety may coalesce to form an eczematous type and large papular lesions may produce plaques or assume an annular configuration. Note the images below.

Polymorphous light eruption on the chest. Courtesy Polymorphous light eruption on the chest. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/_resampled/FitWzY0MCw0ODBd/WatermarkedWyIyNTg0MCJd/pmle-15.JPG).
Polymorphous light eruption on the chest. Courtesy Polymorphous light eruption on the chest. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/_resampled/FitWzY0MCw0ODBd/WatermarkedWyIyNTg0MSJd/pmle-14.jpg).
Polymorphous light eruption on the arm. Courtesy o Polymorphous light eruption on the arm. Courtesy of Waikato District Health Board and DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/_resampled/FitWzY0MCw0ODBd/WatermarkedWyIyNTg0MCJd/pmle-22.JPG).
Polymorphous light eruption on the thighs and hand Polymorphous light eruption on the thighs and hand. Courtesy of DermNet New Zealand (http://www.dermnetnz.org/assets/Uploads/reactions/pmle2.jpg).

Sun-exposed skin, especially that normally covered in winter (eg, upper chest, arms), is affected primarily, but autosensitization may lead to a generalized involvement.

Cheilitis is uncommon in patients in the United States. In such patients, the rare diagnosis of actinic prurigo (AP) is a more likely cause of the inflammatory photosensitivity disorder. Cheilitis is more common in the tropics and might be the only manifestation of the PMLE. In the case of photosensitive cheilitis, PMLE must be distinguished from chronic actinic cheilitis and the eczematous cheilitis produced by photosensitizing agents.


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