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Actinic prurigo - Skin
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Actinic prurigo - Skin

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Contributors: Anne Seidler MD, MBA, Jeffrey D. Bernhard MD, Sarah Stein MD, Karen Wiss MD, Sheila Galbraith MD, Craig N. Burkhart MD, Dean Morrell MD, Lynn Garfunkel MD, Nancy Esterly MD
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Actinic prurigo (AP), also called Hutchinson's summer prurigo or hydroa aestivale, is a photosensitivity disorder. It is triggered by exposure to ultraviolet (UV) radiation and consists of intensely pruritic papules, plaques, or nodules that are typically excoriated and may scar. Secondary lichenification or eczematization may also occur.

AP appears during childhood, typically in females, at about 10-14 years of age on average.

AP is considered a familial dermatosis that is found predominantly in Native Americans and mixed ancestry (Mestizo) populations of Mexico and Central and South America. It has also been described less frequently in white and Asian populations.

  • Intense pruritus
  • Pruritus, tingling, or pain of the vermilion border (83%)
  • Ocular symptoms – photophobia, pruritus, and lacrimation
  • Excoriated papules are apparent, mostly on uncovered skin of the face and distal extremities, but AP can also involve covered sites, especially the lower back and buttocks.
  • Cheilitis (28%)
  • Conjunctivitis (associated conjunctivitis is uncommon in whites)
The precise etiology is not known, but HLA-DR4 is found in 93% of patients with AP (60-70% have the subtype DRB1*0407), suggesting that AP may be an HLA-restricted subset of polymorphous light eruption. It appears that an antigen induced by UV radiation triggers an inflammatory response in susceptible individuals. Previous investigation has demonstrated that Langerhans cells persist in the skin of patients with AP after sun exposure (while they decrease in normal skin that is exposed to sunlight). It is also recognized that AP is more strongly triggered by UVA than by UVB.

The disorder often appears during childhood and resolves after puberty. Less commonly, onset may occur in adulthood. In the latter the eruption seems to be more chronic.


L57.8 – Other skin changes due to chronic exposure to nonionizing radiation

201015007 – Actinic prurigo

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Differential Diagnosis & Pitfalls

  • Polymorphous light eruption (PMLE) – no HLA associations; occurs later, in second and third decades of life; edematous papules and plaques appear  from hours to 1-2 days aftersun exposure; affects exposed skin but often spares the face due to UV exposure year-round; may improve as summer progresses.
  • Solar urticaria – lesions appear within minutes of sun exposure.
  • Hydroa vacciniforme – umbilicated vesicles on sun-exposed skin.
  • Systemic lupus erythematosus – skin biopsies, ANA, anti-Ro, and anti-La antibodies may help distinguish.
  • Juvenile spring eruption – variant of PMLE occurring on the ear helices.
  • Porphyria – check urine and serum porphyrins.
  • Photoaggravated atopic dermatitis – assess for personal and family history of atopy, predominance in flexures; should respond to usual eczema treatment.
  • Lymphomatoid papulosis – skin biopsies.

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Last Updated: 08/14/2013
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Actinic prurigo - Skin
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Actinic prurigo : Lichenified plaque, Photosensitivity, Smooth papule, Pruritus, Sun-exposed distribution
Clinical image of Actinic prurigo
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