Polymorphous light eruption (PMLE)

Overview

Polymorphous light eruption(PMLE) is a skin condition that develops as a rash in response to sun exposure in individuals sensitive to sunlight. Typically characterized by tiny, inflamed bumps or slightly raised skin patches, this reaction is most common during spring and early summer when sunlight exposure peaks. As the summer progresses, occurrences tend to decrease, although the condition often recurs annually.

Also known as polymorphic light eruption, sun allergy, or sun poisoning, the rash generally resolves itself without scarring within ten days. However, those experiencing severe or persistent symptoms may require medication to manage the condition.

Symptoms

Polymorphous light eruption (PMLE) often appears as an itchy rash on sun-exposed areas of the body, characterized by small red bumps, larger red patches, or even blisters. These skin lesions usually develop within hours of sun exposure, though they can sometimes emerge a few days later. Typically, the symptoms of PMLE last for two to three days, but repeated exposure to UV light during this period can extend the duration of the rash.

Rarely, PMLE can also trigger additional symptoms such as fever, headache, and nausea. The rash commonly appears on the chest, neck, arms, and legs, and seldom affects the face. A special form of PMLE, known as juvenile spring eruption, specifically targets the ears of children, predominantly boys, and presents similar dermatological symptoms.

Seek immediate medical care if your rash is widespread, painful, or accompanied by a fever, as these can be signs of a more severe reaction.

Causes

Polymorphous light eruptions (PMLE) occur when individuals sensitive to sunlight, specifically to ultraviolet (UV) radiation, develop a rash. This condition is a form of photosensitivity, where UV rays trigger immune system reactions that cause skin irritation.

• UV radiation: UV radiation, invisible to the human eye, consists of different wavelengths, primarily ultraviolet A (UVA) and ultraviolet B (UVB) that reach Earth. Both types can provoke reactions in photosensitive individuals. Notably, UVB cannot penetrate glass, unlike UVA, which can pass through. Consequently, exposure to sunlight through windows or on skin protected by sunscreen may still trigger a reaction in those with photosensitivity.
• Photosensitivity: In PMLE, sensitivity to sunlight generally diminishes with repeated exposure. Typically, outbreaks occur after the initial one or two sun exposures following an extended period without sunlight, often in the spring or early summer. The condition usually recurs annually after the initial episode. However, over time, some individuals may see a decrease in their sensitivity, resulting in fewer or no annual episodes.

Risk factors

Polymorphous light eruption can affect anyone, however there are a few things that can increase your risk to likely to have the condition.

• Age: individuals in the 20–40 age range.
• Family history: Have a family member with history of the condition.
• Gender: It is common to female than male.
• Location: People who lives in in places that they have minimal sun exposure.
• Medical condition: People who have their skin easily have sunburns.