Last updated: January 2024
Also known as…Photosensitivity Dermatitis and Actinic Reticuloid (PD/AR) Syndrome; persistent light reaction
What is chronic actinic dermatitis?
Chronic actinic dermatitis (CAD) is a rare chronic inflammatory skin condition triggered by abnormal sensitivity to sunlight.
Who gets chronic actinic dermatitis?
CAD typically occurs in men over 50 years of age, particularly those who spend a lot of time outdoors. 1 It is more common in temperate countries and its appearance worsens in summer or after sun exposure.
All races may be affected, and it is not genetically inherited. Individuals with CAD may have other types of inflammatory skin conditions such as atopic dermatitis, seborrheic dermatitis and allergic contact dermatitis. There may also be an association with HIV infection.
What causes chronic actinic dermatitis?
Ultraviolet (UV) radiation causes an inflammatory reaction in the skin; specifically, UVB, UVA and rarely, visible wavelengths of light. The reaction is similar to that seen in allergic contact dermatitis, and it is thought that an antigen in the skin is sensitised by light to stimulate an allergic reaction by the body’s immune system.
What does chronic actinic dermatitis look like?
Affected skin resembles chronic eczema. CAD is severely itchy, red, dry and thickened. Skin creases are prominent.
The rash appears predominantly on sun exposed areas, such as the face, neck, V-shaped area on chest, back of hands and forearms. It is worsened by exposure to sunlight, although some individuals can react to artificial light such as fluorescent lamps.
How is chronic actinic dermatitis diagnosed?
CAD is suspected by its appearance and location on sun exposed areas. Tests the dermatologist may perform to confirm diagnosis include:
- Phototests or light tests, whereby UVB, UVA and/or visible light is directed onto exposed skin to trigger an eczema like skin reaction.
- Blood, urine and stool tests to exclude autoimmune and other light-sensitive disorders.
- Patch testing to identify chemical triggers and exclude allergic contact dermatitis, such as to drugs or plant substances.
- Biopsy of the skin may help distinguish CAD from other inflammatory skin diseases.
How is chronic actinic dermatitis treated?
Treatment options will vary depending on the individual and their needs.
The treatment approach depends on the severity of the disease. Importantly, avoidance to sun exposure is advised for all affected individuals, especially during peak UV times. Sun protection should include wearing clothing to cover bare skin and applying broad spectrum, high-protection sunscreen. If a contact allergy is implicated, it is necessary to cease exposure to the substance.
Treatment may also include:
- Moisturiser
- Fragrance-free soap to clean skin
- A strong steroid cream or ointment
- Topical tacrolimus or pimecrolimus cream
In severe cases, oral immune suppressive treatments may be required, such as:
- Systemic corticosteroids
- Azathioprine
- Ciclosporin
In some cases, desensitisation with controlled exposure to UV radiation may be attempted under dermatologist supervision.
What is the likely outcome of chronic actinic dermatitis?
Although CAD may spontaneously resolve, it is more commonly a chronic condition that persists for life. The symptoms can be controlled with careful sun avoidance and sun protection.