Actinic prurigo

Actinic Prurigo is a chronic skin condition characterized by an intense reaction to sunlight exposure, leading to the development of itchy skin lesions. It is considered a form of photodermatosis, which encompasses a group of conditions caused or exacerbated by sunlight. Actinic Prurigo is more prevalent in certain populations and has a genetic predisposition, often being more common in Native American populations and in individuals of Latin American descent.

Etiology and Pathogenesis

The exact cause of Actinic Prurigo remains unclear, but it is believed to involve a hypersensitive reaction to ultraviolet (UV) radiation. Genetic factors play a significant role, with the condition often running in families. The immune system's abnormal response to sunlight leads to an inflammatory reaction in the skin, manifesting as pruritic (itchy) lesions.

Clinical Features

Actinic Prurigo typically presents in childhood or adolescence, but can occur at any age. The condition is characterized by the appearance of pruritic papules, nodules, and plaques. These lesions are most commonly found on areas exposed to the sun, such as the face, neck, and arms, but can also appear on covered areas. The lesions can be persistent and may worsen with further sun exposure. In some cases, Actinic Prurigo can also affect the lips and the conjunctiva of the eyes, leading to cheilitis and conjunctivitis, respectively.

Diagnosis

Diagnosis of Actinic Prurigo is primarily clinical, based on the patient's history and the characteristic appearance of the lesions. Phototesting, where the skin is exposed to various wavelengths of light, can help confirm the diagnosis by reproducing the lesions with UV exposure. Skin biopsy may also be performed to rule out other conditions and to confirm the diagnosis histologically.

Treatment

Management of Actinic Prurigo focuses on photoprotection and the reduction of symptoms. Patients are advised to avoid sun exposure, wear protective clothing, and use broad-spectrum sunscreens. Topical corticosteroids and calcineurin inhibitors can be used to reduce inflammation and itching. In more severe cases, systemic treatments such as antimalarial drugs, thalidomide, or immunosuppressants may be considered. Phototherapy with UVB or PUVA (psoralen plus UVA) can be beneficial in some patients by inducing tolerance to sunlight.

Prognosis

The prognosis of Actinic Prurigo varies. While the condition can significantly impact the quality of life due to its chronic nature and the need for ongoing sun protection, many patients experience improvement with appropriate management. In some cases, the severity of the condition may decrease with age.

Epidemiology

Actinic Prurigo is more common in females than in males and has a higher prevalence in certain ethnic groups, particularly Native Americans and individuals of Latin American descent. The condition is less common in Caucasian populations.

See Also

• Photodermatitis
• Sunscreen
• Dermatitis
• Ultraviolet radiation