polymorphic light eruption

Last edited 08/2023 and last reviewed 08/2023

Polymorphic light eruption is a common idiopathic photosensitive disorder (1,2,3) which is frequently mis-diagnosed with miliara ("prickly heat") . It occurs in about 10-20% of the population with females affected more frequently than males in the ratio of 4:1 (3).

Presentation is usually in late adolescence and young adulthood, often early in the summer following exposure to ultraviolet (A and B wavelengths),intermittent eruption of non-scarring, erythematous itchy papules, plaques or vesicles induced by UV irradiation of sun-exposed skin (1,2)

  • face, neck, and the upper and lower extremities are most commonly involved
  • symptoms are worse in spring and early summer
  • usually has its onset within the first three decades of life (3)
  • also is a genetic component - appears to cluster in families: it has been estimated that the prevalence of PLE was 21 and 18% in monozygotic and dizygotic twins, respectively (2)

Click here for images of polymorphic light eruption

First line of treatment for polymorphic light eruption includes sun avoidance, sunscreens and topical corticosteroids (2)

  • new generation broad-spectrum sunscreens, with high sun protection factor for UVB (SPF), together with longer wavelength UVA protection, have been reported to confer total or partial protection in up to 90% of patients
  • second line therapies includes systemic corticosteroids and photo(chemo)therapy (2)

Prognosis

  • study evidence revealed disease improved in a substantial number of patients (i.e., 77% of females and 59% of males) over the years, it took 25 years until one third of patients had normalized from polymorphic light eruption (3)
    • persistence of skin lesions for more than 1 week under daily life conditions may predict a prolonged course of the disease over the years

Notes:

  • polymorphic light eruption in Indian skin
    • unique feature of this condition in Indian skin is the pigmentary change which varies from hypopigmented to hyperpigmented lesions (4)
      • pigmentary changes may occur alone or in combination with erythematous or skin-colored lesions
      • pigmentary lesions are seen in more than 50% of lesions
      • pigmentary changes may persist after the lesions subside

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