Dermatology - Polymorphic Light Eruption

This guide has been written to help answer some of your questions about polymorphic light eruption. You may have been given this guide because you have been diagnosed with polymorphic light eruption or because we think this might be the cause of your symptoms.

What is polymorphic light eruption?

Polymorphic light eruption (sometimes shortened to PLE) is a skin complaint caused by sunlight. The light eruption part of the name comes from the fact that the rash appears after sunlight. The polymorphic part of the name comes from the fact that the rash can take many different forms from small red lumps to large red patches and blisters (poly means many and morphic means shapes).

People with PLE are usually affected between the spring and autumn. Sometimes as little as 30 minutes sun exposure is enough to cause the problem. A person who has PLE may notice an itchy rash appearing 2 or 3 days after exposure to sunlight. The rash may last for 7 to 10 days and usually heals without scarring. The rash usually appears on the parts of the skin that are exposed to sunlight but doesn’t always appear on the face. PLE can sometimes come up even through window glass or thin clothing. 

Who suffers from PLE?

• PLE is quite a common complaint with 15% of the population affected
• It is more common in women than men
• It affects all skin types but is more common in those who are fair
• It usually starts under the age of 30
• It can run in families and about 20% of people with PLE will have another family member affected
• It can vary in severity from mild to severe

What causes PLE?

It is thought that PLE is due to an alteration in the way the skin's immune system reacts to sunlight. This could be regarded as a form of sun allergy.

Is PLE infectious?

No. There is no risk of other people catching PLE from you.

Does having PLE increase your risk of cancer?

No. Experts believe PLE is more like an allergy.

Can PLE be cured?

No treatment will get rid of PLE for ever but by careful sun avoidance and use of sunscreens the rash can often be prevented, and there are treatments that can help (see below). Occasionally PLE may go away by itself but in the majority of cases people are affected every year.

How will having PLE affect me?

If you have been diagnosed as having PLE you may have to make changes to your lifestyle which can be restrictive. The doctor can prescribe corticosteroid cream or ointment to be applied in the evening if the rash appears, but prevention is better than cure.

You should try to:

• Avoid the sun during conditions that provoke your photosensitivity and particularly when sunlight is intense. In the UK this is mainly between 11 and 3pm, although other times of day can be troublesome
• Wear protective clothing, with close/tightly woven fabrics, long sleeves and trousers, hats with broad brims. Glasses and sunglasses with wrap around lenses can also be helpful
• Use a sunscreen that is SPF 30 or above (high UVB protection) and also has high UVA protection. Remember to re-apply the sunscreen evenly and often
• Learn how much sunlight your skin can tolerate and keep within that limit
• Make sure you introduce your skin to sunlight gradually in the spring

What about vitamin D?

Importantly, in order for people to make enough Vitamin D themselves, they need a certain amount of sun exposure. The sun protection measures needed for people with PLE mean Vitamin D deficiency is a real risk and this does require treatment with supplements if it occurs. This can be monitored through blood tests.

How can PLE be treated?

Sunscreens

You will be provided with sunscreens on prescription, and these will help prevent the rash developing. Sunscreen should be applied as thickly and evenly as possible and re-applied often.

Topical creams

Your doctor may prescribe corticosteroid creams or ointments to put on your skin in the evening if the rash appears. Steroid creams can be strong and should only be applied sparingly and while the rash is there. You should stop applying steroid cream when the rash has gone. More information about steroid creams can be found on the British Association of Dermatologists website, at https://www.bad.org.uk/pils/topical-corticosteroids/.

Desensitisation or UV Treatment

Sometimes the resistance of your skin to the effects of the sun can be increased. This is done in a hospital department and will involve visiting the hospital three times a week for about 5 weeks in the spring. It involves gradually exposing your skin to a little more ultraviolet light every visit to try to build up your skin’s resistance. The effects of desensitisation are lost in the winter so you will have to build up your resistance again in the spring.

Hardening or Toughening

Some people with PLE may be able to increase the resistance of their skin at home. This involves going outside for short periods in the spring to build up your resistance. You might find the time is as short as a few minutes at first, but you may be able to gradually build this up to longer times. You will have to be careful not to overdo it, but as you understand more about how much light triggers your rash you will be able to judge how long to stay out. The effects of hardening are lost in the winter so you will have to build up your resistance again in the spring. We have included an example of how you might try to toughen your skin in the spring.

Example:

Mrs Smith knows her PLE rash usually appears in the evening if she has been out in the sun during the day. Mrs Smith has been toughening her skin in the spring and this is her diary, please see example on the next page.

Food supplements

There is some research suggesting that fish oil rich in omega 3 oils can help some patients with PLE. Unfortunately, it is hard to say how much the fish oil will help you because some people are helped a lot, but in some people, it does not seem to make a difference. If you are interested in trying the fish oils you would need to take 10 capsules daily from the spring right through the summer. However, if the preparation is more concentrated, 2-3 capsules will be sufficient.

Some research has also suggested that another supplement, Polypodium leucotomos extract (“Fernblock” in Heliocare tablets), can be helpful in some cases. This is used more widely in continental Europe, but some people have reported some benefit in PLE. It is not available on prescription and would have to be purchased.

Contact us

The Photobiology Unit can be contacted on 0161 206 4081 or by email
Photobiology.Salford@nca.nhs.uk

Further Information

The British Association of Dermatologists produces a series of patient information leaflets. They can be contacted at The British Association of Dermatologists, 4 Fitzroy Square, London or if you have access to the internet on their web site www.bad.org.uk/ pils