Actinic prurigo: Skin rash due to sun exposure

Actinic prurigo is a skin condition caused by an abnormal response to sunlight. The patient has small, intensely itchy papules (bumps, lumps and other lesions) on areas exposed to the sun, although sometimes areas covered by clothing are also affected. The treatment of the rash consists of sun protection measures, medication and sometimes other therapies. The outlook is variable, but in most cases the skin disorder is chronic and often relapses, especially in the spring and summer months. The doctor Escalona first described the skin disease in the medical literature in a patient in Mexico in 1954.

  • Synonyms of actinic prurigo
  • Epidemiology of skin disease
  • Causes: Often due to sun exposure
  • Symptoms: Itchy bumps and spots on skin
  • Associated conditions
  • Diagnosis and examinations
  • Treatment of skin rashes
  • Prognosis: Often relapse in spring or summer
  • Complications

 

Synonyms of actinic prurigo

Doctors sometimes label actinic prurigo as:

  • actinic prurigo
  • Hutchinson prurigo
  • prurigo actinica
  • prurigo solaris
  • solar prurigo

 

Epidemiology of skin disease

Actinic prurigo potentially affects patients of all skin types. However, persons of Latin American and American Indian descent with darker skin types are more commonly affected. The disease is therefore more common in Mexico and Central and South America. Most patients in these areas live at high altitudes. Individuals in Europe and Asia are rarely affected by the skin disease. Furthermore, patients of any age may be affected. About one in three patients are children. The condition usually first occurs before puberty. When the condition appears during childhood, both boys and girls are equally affected. However, when actinic prurigo appears in adults, women suffer from the skin disease twice as often as men. The disease is present throughout the year, but the symptoms are worse in the summer months.Sun exposure is often the cause of the disease / Source: Blueeve, Pixabay

Causes: Often due to sun exposure

Actinic prurigo is a so-called photodermatosis. Exposure to long- and short-wave ultraviolet radiation (UVA and UVB) causes symptoms of the skin condition. Sometimes the skin covered by clothing, such as the buttocks, is also affected. The role of sunlight is therefore unclear in September 2020. Actinic prurigo may be an immunologically mediated genetic disease, because some patients have a family history of the disease.

Symptoms: Itchy bumps and spots on skin

The condition mainly affects areas exposed to the sun. Consequently, parts of the face such as the cheeks, nose, forehead, chin and earlobes are usually affected by the skin disease. The lips are also often affected; sometimes this is even the only symptom of actinic prurigo. In addition, symptoms are sometimes often manifested on the neck and chest and the tops of the arms and hands. The conjunctiva of the eye is affected in approximately half of the patients.Patients with actinic prurigo experience an intensely itchy skin rash, which consists of small, red and inflamed bumps (papules), thickened areas (plaques) and lumps (nodules). In most patients, the rash appears hours or days after sun exposure. Chronic scratching, ulceration, blistering, crusting and scaling are present in 60-70% of patients.

Associated conditions

Patients who suffer from actinic pruritus are more likely to develop actinic cheilitis, an inflammation of the lip caused by sun damage. Ocular pseudopterygium is also often present in patients with the skin disorder.

Diagnosis and examinations

Diagnostic research

The diagnosis is made clinically. It is possible to have the mucous membrane tested for the presence of lymphoid follicles. This symptom is characteristic of actinic prurigo.

Differential diagnosis

The condition is sometimes reminiscent of atopic dermatitis (atopic eczema: skin disease with itching), but the symptoms are more severe in areas exposed to the sun. Actinic prurigo also resembles the skin lesions of Kwashiorkor (starvation edema with abdominal distension). The following conditions are also differential diagnoses:

  • acute cutaneous lupus erythematosus
  • discoid lupus erythematosus
  • hydroa vacciniforme (skin disease due to exposure to sunlight)
  • Jessner lymphatic infiltration of the skin
  • medication-induced light eruption
  • polymorphic light eruption (skin disease due to sun exposure)
  • protoporphyria
  • prurigo nodularis (skin condition with very itchy bumps)
  • solar urticaria (skin condition after exposure to UV rays)

 Moisturizers often relieve itching / Source: Kiyok, Wikimedia Commons (CC BY-SA-3.0)

Treatment of skin rashes

There is no treatment for actinic prurigo as of September 2020. The doctor advises a patient with mild symptoms to avoid sun exposure by staying indoors or in the shade, wearing protective clothing, sunglasses and wide-brimmed hats, and wearing a use broad spectrum sunscreen. Some medications relieve symptoms of patients with severe actinic prurigo:

  • antimalarials such as hydroxychloroquine (anti-inflammatory effect)
  • Thalidomide: After an improvement in the symptoms, the patient should slowly reduce this medicine. In the event of a relapse, it is possible to restart this medication. This medication is not recommended for women who wish to become pregnant because Thalidomide can be harmful to an unborn fetus.
  • topical (applied to the skin) corticosteroids (powerful anti-inflammatories)
  • moisturizers to relieve itching

 

Prognosis: Often relapse in spring or summer

In some cases, the condition resolves spontaneously in early adult life. However, in most cases the patient suffers from recurrences and outbreaks throughout life. Relapses occur especially in spring and summer.

Complications

Known complications of actinic prurigo include:

  • secondary bacterial infections
  • contact dermatitis (allergic eczema)
  • impetigo (bacterial skin infection on face and limbs)

 

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  • Actinic keratosis: Skin lesions due to sun exposure

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