Chronic actinic dermatitis
Although the etiology is unclear, one proposed pathophysiologic mechanism is that CAD results from an endogenous cutaneous antigen. This antigen is normally suppressed, but chronic immunosuppression from chronic ultraviolent light exposure may cause activation of this antigen, resulting in a cutaneous reaction similar to that of allergic contact dermatitis.
CAD is most commonly seen in male patients over the age of 50, although the condition can be seen in women and also rarely in younger patients. In younger patients, it is usually associated with a history of atopic dermatitis. In general, affected patients of all ages often have a history of atopic dermatitis and/or multiple contact allergies. CAD can occur in any skin type and anywhere in the world, although it is more commonly seen in patients with Fitzpatrick skin types V and VI and in temperate climates.
CAD may be a presenting sign of human immunodeficiency virus (HIV), especially in younger CAD patients. If the diagnosis of CAD is considered, testing for HIV is recommended for patients with positive risk factors for HIV.
L57.8 – Other skin changes due to chronic exposure to nonionizing radiation
52636001 – Actinic reticuloid
- Polymorphous light eruption – Occurs in younger patients and in discrete attacks with clearance of lesions between flares.
- Photoexacerbated drug eruption – Usually appears more edematous and erythematous, but chronic cases may have lichenification. Check the medication list of the patient for potential causes.
- Acute / subacute cutaneous lupus erythematosus – Malar distribution or polycyclic erythematous scaly plaques, usually not lichenified.
- Porphyrias (see porphyria cutanea tarda, variegate porphyria) – Can mimic this disease; rule out with stool / urine / serum porphyrins as appropriate.
- Cutaneous T-cell lymphoma – Not confined to photoexposed skin (although there is a rare photosensitive form of mycosis fungoides, and spillover to non-exposed sites can occur in CAD).
- Pellagra – May present similarly to CAD. The classic symptoms of diarrhea and dementia may or may not coincide. Check serum niacin levels if there are pellagra risk factors such as a history of alcohol abuse.