|Polymorphous Light Eruption
Polymorphous light eruption is a common rash that occurs as a result of sensitivity to sunlight (photosensitivity). People who are sensitive to sunlight can experience a reaction after an episode of intense sun exposure, usually in the spring or early summer. The rash typically appears as itchy, red spots that develop up to a day after being in the sun. The inflammation occurs most often on the front of your neck and chest as well as your arms and thighs.
Sometimes called sun poisoning, polymorphous light eruption usually resolves without medical treatment in seven to 10 days. But it can recur and become worse the following spring or summer. Cortisone creams or antihistamines can help if the rash is uncomfortable. Gradually increasing sun exposure times in the spring and avoiding intense sun exposure is the best way to treat and prevent polymorphous light eruption.
The cause of polymorphous light eruption is exposure to UV radiation. UV radiation is a wavelength of sunlight in a range too short for the human eye to see. Commercial tanning lamps and tanning beds also produce UV radiation. UV light is divided into three wavelength bands — ultraviolet A (UVA), ultraviolet B (UVB) and ultraviolet C (UVC). Only UVA and UVB rays reach the earth.
UVA radiation is most likely to trigger polymorphous light eruption. But some people react to both UVA and UVB rays. Why some people are more sensitive to UV radiation is unknown.
Risk Factor :
Polymorphous light eruption affects all races but is more common in fair-skinned individuals who live in northern climates. And though it can start at any age, it usually begins before age 30.
When to seek medical advice
If you experience skin reactions after relatively minor exposures to sunlight, see your doctor. He or she can confirm the diagnosis of polymorphous light eruption and help you create a treatment plan to prevent future episodes.
Also, see your doctor if the rash and inflammation :
- Covers large portions of your body
- Is accompanied by a high fever or extreme pain
- Begins to blister
- Continues despite your efforts to avoid sun exposure
- Occurs after you take certain medications, such as high blood pressure medications or nonsteroidal anti-inflammatory drugs (NSAIDs)
Polymorphous light eruption symptoms include a red rash that develops after exposure to ultraviolet (UV) radiation. UV radiation is found in sunlight and commercial tanning lamps and tanning beds. The rash begins within hours after UV exposure and can last up to a week or longer. The amount of UV radiation needed to trigger a reaction varies greatly.
The rash can look different from person to person but typically includes one or more of the following :
- Small bumps
- Blistering and swelling
- Stinging or pain
Polymorphous light eruption may also cause chills, headache, nausea and a general sick feeling.
Polymorphous light eruption usually affects people in northern climates after one or two exposures to sunlight in the spring or early summer. It may also affect people who vacation in sunny locations during the winter. With each exposure, light sensitivity decreases so that the eruptions typically stop by the end of the summer. The inflammation may return the following spring, however, after new exposures to sunlight.
Your doctor is likely to conduct a thorough physical exam and ask questions about your medical history. Diagnosis of polymorphous light eruption is typically based on your skin's appearance and your history of sun exposure.
To confirm the diagnosis and rule out other conditions, your doctor may order tests, including blood tests or a skin biopsy. Your doctor may also perform phototesting, a procedure in which small areas of your skin are exposed to measured amounts of UV light to try to reproduce the problem.
Other conditions that can look like polymorphous light eruption include :
- Photoallergic reaction. This form of sun allergy causes an itchy red rash due to changes in your immune system. When this occurs, your skin reacts each time it's exposed to sunlight after coming in contact with a particular drug, chemical or plant. Signs and symptoms can extend to areas not exposed to the light. Once your body becomes sensitized to a certain substance, you can react to it again and again.
- Solar urticaria. This form of sun allergy produces hives — raised, red, itchy welts of various sizes that appear and disappear on your skin. It's triggered by sunlight and can appear on uncovered skin within minutes of exposure. Solar urticaria typically resolves several hours after covering up.
- Lupus rash. The skin problem most typically associated with lupus is a butterfly-shaped rash (malar rash) that develops across the cheeks and bridge of the nose. This malar rash may be flat or raised and may be blotchy or completely red in the affected areas. Some people with lupus develop skin lesions (subacute cutaneous lesions) that initially resemble small bumps but that eventually turn scaly and itchy. Others have large, flat, itchy lesions with clear centers, somewhat resembling hives. These rashes usually appear after exposure to sunlight.
Polymorphous light eruption treatment usually isn't necessary because the rash typically resolves on its own in seven to 10 days. To lessen the reaction and prevent future episodes, practice sun protection measures: Limit time spent in the sunlight, use sunscreen and wear protective clothing. Self-care measures, such as using a nonprescription anti-inflammatory cream, may help soothe your skin and reduce itching and discomfort.
If prevention steps aren't effective and you continue to experience sun reactions, your doctor may prescribe a medication, such as a corticosteroid cream, to reduce the inflammation.
Prevention is the best way to manage polymorphous light eruption.
- Avoid the sun between 10 a.m. and 4 p.m. Because the sun's rays are strongest during this time, try to schedule outdoor activities for other times of the day. If you are unable to avoid being in the sun, limit the amount of time you're outdoors during these peak hours.
- Use sunscreen. Before spending time outdoors, apply a broad-spectrum sunscreen with a sun protection factor (SPF) of at least 15. Some sunscreens contain substances that block ultraviolet A (UVA) as well as ultraviolet B (UVB) rays. To identify UVA-blocking creams, first look to see if the product is labeled "broad spectrum." Then, look on the ingredient labels for oxybenzone, sulisobenzone, dioxybenzone, avobenzone (Parsol 1789), titanium dioxide or methyl anthranilate.
- Cover up. For protection from the sun, wear tightly woven clothing that covers your arms and legs and a broad-brimmed hat, which provides more protection than does a baseball cap or golf visor. You might also consider wearing clothing or outdoor gear specially designed to provide sun protection.
- Phototherapy. Small, incremental exposures to sunlight or UV light over the course of several weeks may prevent flare ups prior to a winter vacation or spring season.