What is actinic dermatitis?

Actinic dermatitis is a photosensitive disorder of the skin that occurs after exposure to ultraviolet or visible light.  It is part of a subgroup of photosensitive disorders called the idiopathic photodermatoses, meaning the cause is unknown.  Other names for actinic dermatitis include chronic actinic dermatitis, photosensitive dermatitis, photosensitive eczema or persistent light reactivity.  

Actinic dermatitis is a long-standing eczematous eruption on sun-exposed skin.  Eczematous patches are red and itchy patches distributed to face, neck, dorsal hands, scalp and upper chest.  The skin overlying these patches can become thick with increased skin markings, this is called lichenification.  Papules and plaques may also be seen. In some cases breakages of hair on eyebrows, eyelashes and scalp may occur.

Actinic dermatitis can affect both light and dark-skinned individuals, especially elderly men with a long history of sun exposure and patients with a personal history of allergic contact dermatitis.

How does actinic dermatitis occur?

While the exact cause of actinic dermatitis is unknown, it is thought to be an immunological response triggered by exposure to UVA, UVB or visible light.  

How is actinic dermatitis diagnosed?

Actinic dermatitis can resemble more serious skin conditions such as cutaneous T-cell lymphoma and may be difficult to distinguish from other types of dermatitis.  Patch testing and photo-testing can be useful for diagnosis and can reveal if the patient has an increased sensitivity to ultraviolet or visible light. 

How is actinic dermatitis treated?

Treatment of actinic dermatitis is difficult.  Avoidance of sun-exposure and strict sun protection is important but difficult to accomplish for some patients.  Avoiding other contact allergens such as certain sunscreens may help minimize irritation. Application of topical corticosteroids or immunosuppressants may help reduce the local immune response.  In severe cases oral immunosuppressant therapy may be prescribed.