History
Actinic prurigo is clinically different from polymorphous light eruption (PLE) and is characterized by an intensely itchy, excoriated papular and nodular eruption that lasts longer than PLE. It can affect any area that is exposed to the sun.
Patients typically report onset or exacerbation in spring and summer, but many patients have clinical symptoms that persist during autumn and winter, particularly in tropical areas. [22, 23]
In 65% of patients, the lips are involved, and, in 10% of patients, the lips are the only sites of involvement. In 45% of patients, the conjunctivae are affected. [3, 4]
Physical Examination
Lesions are erythematous papules, appear singly or in itchy groups, and can form large plaques, as shown below. Lesions have serosanguineous crusting, and, because the ailment is chronic, lichenification is eventually seen. Chronic scratching of the face can produce pseudoalopecia of the eyebrows.
Multiple itchy papules coalescing into plaques on the neck. These lesions are similar to lesions of polymorphous light eruption. Note the excoriations induced by scratching.
The dermatitis is generally disseminated, bilateral, and symmetric. It affects sun-exposed areas, such as the cheeks, the dorsum of the nose, the forehead, the chin, the ear lobes, the V of the neck and the chest, the extensor surfaces of the arms and the forearms, and the dorsum of the hands. In severe and long-standing disease, lesions in covered areas can also be seen, although this finding is infrequent. See the images below.
One third of patients are children. The nose is frequently affected. This clinical feature is useful in distinguishing it from other entities, such as atopic dermatitis.
Photodistribution of lesions over the body. Note the hypopigmented areas of the skin, which are very common after intense scratching in children.
Lichenified plaques, excoriated nodules, and atrophic scars on the dorsal aspect of hands are frequently seen in children.
Conjunctival involvement, as shown below, is manifested by hyperemia, brown pigmentation, photophobia, epiphora, and formation of pseudopterygium. This finding is present in 45% of patients.
One half of patients have bilateral conjunctivitis. Eye protection is needed to avoid disease progression.
Erythematous and very itchy plaques on solar exposure areas of the face and pseudopterygium are commonly observed in actinic prurigo.
Lesions on the lips are manifested by cheilitis (as shown below), and pruritus, edema, scales, fissures, crusts, and ulceration may be present. This finding occurs in 60-70% of patients. [3, 4]
When the skin on the nose is not affected, photosensitized atopic dermatitis, as shown below, is more likely than actinic prurigo.
Young girl with a history of atopic dermatitis and itchy, lichenified plaques on her face for the last 3 months. Atopic dermatitis with photosensitivity is the main differential diagnosis with actinic prurigo in children.
Causes
UVA and UVB light seem to be the main provoking agents. This observation is supported by the fact that most patients live at high altitudes (>1000 m above sea level), and the condition improves in many patients when they move to lower altitudes. However, some patients who are affected already live at sea level. [22, 23, 33]
Some authors are considering a food photosensitizer or a nutritional selective deficiency as a cause; however, no evidence proves this theory. [33]
Complications
Common complications are secondary infection and irritant contact dermatitis, mainly due to the use of sunscreens. Impetigo is another typical complication. See the images below.
Impetiginous area located on the right ear lobe due to intense scratching following an acute relapse.
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Itchy plaques mainly on photoexposed areas of the face; these plaques are characteristic of actinic prurigo.
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Photodistribution of lesions over the body. Note the hypopigmented areas of the skin, which are very common after intense scratching in children.
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Multiple itchy papules coalescing into plaques on the neck. These lesions are similar to lesions of polymorphous light eruption. Note the excoriations induced by scratching.
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One third of patients are children. The nose is frequently affected. This clinical feature is useful in distinguishing it from other entities, such as atopic dermatitis.
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One half of patients have bilateral conjunctivitis. Eye protection is needed to avoid disease progression.
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About 75% of patients have cheilitis, which can take the form of solid lesions or erosions.
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A phototest with UV-B light shows reproduction of lesions on the inner aspect of the arm. The result from the phototest with UV-A light was negative.
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Histologic examination shows acanthosis, mild spongiosis, edema of the lamina propria, and a moderate-to-dense perivascular lymphocytic inflammatory infiltrate.
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A close-up view shows edema of the lamina propria as well as a lymphocytic inflammatory infiltrate in the dermis.
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Young girl with a history of atopic dermatitis and itchy, lichenified plaques on her face for the last 3 months. Atopic dermatitis with photosensitivity is the main differential diagnosis with actinic prurigo in children.
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Actinic cheilitis resulting from actinic prurigo.
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Erythematous and very itchy plaques on solar exposure areas of the face and pseudopterygium are commonly observed in actinic prurigo.
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Lichenified plaques, excoriated nodules, and atrophic scars on the dorsal aspect of hands are frequently seen in children.
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Contact dermatitis due to sunscreen in a patient with actinic prurigo.
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Impetiginous area located on the right ear lobe due to intense scratching following an acute relapse.
