Disease: Polymorphous light eruption

Overview

Polymorphous light eruption, also known as polymorphic light eruption, is a rash caused by sun exposure in people who have developed sensitivity to sunlight. The rash usually appears as red, tiny bumps or slightly raised patches of skin.

Polymorphous light eruption occurs most often during spring and early summer when a person's exposure to sunlight increases. Repeat episodes are less likely as the summer progresses. But the rash often recurs each year after the first incident.

Polymorphous light eruption usually goes away on its own without scarring within 10 days. People with severe or persistent rashes may need treatment with medication.

Source: http://www.mayoclinic.com

Symptoms

The term "eruption" refers to the rash, which usually appears 30 minutes to several hours after exposure to sunlight. The rash typically appears on areas of the body that tend to be covered during winter but exposed in summer: the upper chest, front of the neck and arms.

Characteristics of the rash may include:

  • Dense clusters of small bumps and blisters
  • Red, raised rough patches
  • Itching or burning

Rarely people may have other signs or symptoms, such as fever, chills, headache or nausea. These conditions may be the result of an associated sunburn rather than polymorphous light eruption.

When to see a doctor

See your doctor if you have any rash with no obvious cause, such as a known allergy or recent contact with poison ivy.

Polymorphous light eruption rashes look similar to rashes caused by other diseases, some of which are serious. So it's important to get a prompt diagnosis and appropriate treatment.

Seek immediate medical care if your rash is:

  • Widespread
  • Painful
  • Accompanied by fever

Source: http://www.mayoclinic.com

Causes

The exact cause of polymorphous light eruption isn't well-understood. The rash appears in people who have developed sensitivity to components of sunlight, and in particular ultraviolet (UV) radiation from the sun or other sources, such as tanning beds or tanning lamps. This sensitivity is called photosensitivity. It results in immune system activity that causes a rash.

UV radiation

UV radiation is a wavelength of sunlight in a range too short for the human eye to see. UV light that reaches the earth is divided into two wavelength bands — ultraviolet A (UVA) and ultraviolet B (UVB).

A person with photosensitivity can react to both types of UV radiation. Although UVB doesn't penetrate glass, UVA does. UVA may even penetrate through most sunscreens. So exposure to sunlight through windows or even sunscreen-protected skin may cause a reaction in some people with photosensitivity.

Photosensitivity

Sensitivity to sunlight lessens with repeated exposure in polymorphous light eruption. Features of polymorphous light eruption are somewhat predictable:

  • An episode is most likely to occur after the first one or two exposures to sunlight after a long period of no exposure. This usually means that an episode occurs during the spring or early summer or during a winter vacation in a sunnier location.
  • Episodes are less likely to occur as the summer progresses.
  • After the first episode of polymorphous light eruption, additional episodes are likely to recur each spring or early summer.
  • Some people gradually become less sensitive over several years and eventually no longer experience the annual rash.

Source: http://www.mayoclinic.com

Diagnosis

Your doctor can probably make a diagnosis of polymorphous light eruption based on a physical exam and your answers to questions. He or she may also have you undergo laboratory tests in order to confirm a diagnosis or rule out other conditions. Tests may include:

  • Skin biopsy. Your doctor may remove a sample of rash tissue (biopsy) for examination in a lab.
  • Blood tests. A nurse or assistant may draw blood for laboratory tests.
  • Phototesting. Your doctor may refer you to a specialist in skin conditions (dermatologist) for phototesting. During the test small areas of your skin are exposed to measured amounts of UVA and UVB light to try to reproduce the problem. If your skin reacts to the UV radiation, you're considered sensitive to sunlight (photosensitive) and may have polymorphous light eruption or another light-induced disorder.

Other light-induced conditions

Your doctor may need to rule out other disorders characterized by light-induced skin reactions. These conditions include:

  • Chemical photosensitivity. A number of chemicals — drugs, medicated lotions, fragrances, plant products — can induce photosensitivity. When this occurs, your skin reacts each time it's exposed to sunlight after ingesting or coming into contact with a particular chemical.
  • Solar urticaria. Solar urticaria is a sun-induced allergic reaction that produces hives — raised, red, itchy welts that appear and disappear on your skin. The welts can appear within a few minutes of sun exposure and last for a few minutes to hours. Solar urticaria is a chronic condition that can last for years.
  • Lupus rash. Lupus is an inflammatory disorder that affects a number of body systems. One symptom is the appearance of a discolored, bumpy rash on areas of skin exposed to sunlight, such as the face, neck or upper chest.

Source: http://www.mayoclinic.com

Lifestyle and home remedies

Self-care measures that may help ease your signs and symptoms include:

  • Applying anti-itch cream. Try an over-the-counter (nonprescription) anti-itch cream, which may include products containing at least 1 percent hydrocortisone.
  • Taking antihistamines. If itching is a problem, oral antihistamines may help.
  • Using cold compresses. Apply a towel dampened with cool tap water to the affected skin, or take a cool bath.
  • Leaving blisters alone. To speed healing and avoid infection, leave blisters intact. If needed, you can lightly cover blisters with gauze.
  • Taking a pain reliever. An over-the-counter pain medication may help reduce redness or pain. These include ibuprofen (Advil, Motrin IB, others), acetaminophen (Tylenol, others) and naproxen sodium (Aleve, others).

To lessen the likelihood of recurring episodes of polymorphous light eruption, take the following precautions:

  • Avoid the sun between 10 a.m. and 2 p.m. Because the sun's rays are most intense during this time, try to schedule outdoor activities for other times of the day.
  • Use sunscreen. Fifteen to 30 minutes before going outdoors, apply a broad-spectrum sunscreen, one that provides protection from both UVA and UVB light. Use a sunscreen with a sun protection factor (SPF) of at least 30. Apply sunscreen generously, and reapply every two hours — or more often if you're swimming or perspiring. If you're using a spray sunscreen, be sure to cover the entire area completely. 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.

    Consider wearing clothing designed to provide sun protection. Look for clothes labeled with an ultraviolet protection factor (UPF) of 40 to 50. Follow care instructions on the label of UV-blocking clothes to maintain their protective feature.

Source: http://www.mayoclinic.com

Risk factors

Anyone can develop polymorphous light eruption, but several factors are associated with an increased risk of the condition:

  • Being female
  • Experiencing the first episode during the teenage years or 20s
  • Having light skin and living in northern regions
  • Having a family history of the condition

Source: http://www.mayoclinic.com

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