Metabolic photodermatoses

Metabolic photodermatoses are a type of skin disorder caused by a breakdown in the body's metabolism when it is exposed to ultraviolet radiation, most often from the sun. People with metabolic photodermatoses experience skin rashes, itching, or blisters upon exposure to UV light. This is caused by the body's inability to metabolize a normally harmless metabolite into a harmless end product, which often leads to a reaction in the skin. It is important to note that metabolic photodermatoses is not an allergy or true photodermatoses. True photodermatoses are caused by a direct reaction to ultraviolet radiation. In metabolic photodermatoses, the ultraviolet radiation triggers the body’s metabolism to break down the innocuous metabolite into an allergen or irritant. This then causes a reaction in the skin. There are several common types of metabolic photodermatoses, including polymorphic light eruption, chronic actinic dermatitis, and xeroderma pigmentosum. Each of these conditions has slightly different symptoms. Polymorphic light eruption is the most common type of metabolic photodermatoses. People with this condition may experience an itchy red rash after exposure to the UV light, typically occurring on areas such as the limbs and face. This rash is not serious but can be very uncomfortable. Chronic actinic dermatitis is another type of metabolic photodermatoses. People with this skin disorder may experience chronic itching, burning, and scaling of the skin after UV light exposure. The most visible symptom of chronic actinic dermatitis is the formation of polygonal areas of redness that can appear on the skin. Xeroderma pigmentosum is a genetic disorder that impairs the skin’s ability to repair the damage caused by UV light exposure. People with this condition are at an increased risk for skin cancer and may experience lesions, hyperpigmentation, and fragility of the skin. Overall, metabolic photodermatoses are caused by a breakdown in the body's metabolism when it is exposed to ultraviolet radiation. While metabolic photodermatoses are not the same as true photodermatoses, they can be uncomfortable and in severe cases can even lead to skin cancer.