Most common photo-induced skin rash - PMLE: Ultimate guide to patients

 

It was the weekend and you just went to the nearby beach to have some fun. The next morning you suddenly realized that you are having some itchy skin rash over your back of the neck and upper arms. It could be PMLE.

Or

Your summer holiday has just started and after few days of outdoor activity there is itching and rash over the chest and upper back. It might be PMLE.

So what is PMLE?

PMLE stands for Polymorphous Light Eruption

P-Polymorphic/polymorphous – several different forms or characters

L- light induced

E- Eruption – spot or rash over skin

PMLE is the most common type of photo induced skin rash that generally occurs over sun exposed areas of skin after a certain period of intense exposure to sunlight (Ultra violet ray).

Who gets this type of skin rash?

It is the most common photo induced skin problem.

Most commonly occurs in age between 21-30 years and more common in females ⁽¹⁾.

According to various Indian studies it affects around 2-13.5% people in various parts of India ⁽²⁾.

How does it feel (clinical features)?

It particularly occurs after a delay of at least 6 hours to few days following the exposure to high intensity sunlight. Exposure can be for 10 minutes to several hours.

If no further exposure to Ultra Violet Ray(UVR) occurs, then it usually resolves within 7-10 days without scarring.

As the season progresses your skin may become less sensitive and symptoms may occur in less severe manner.

Skin lesions are polymorphous which means it can be of various characters, size and shape but in a single patient usually one type is seen. In my practice I have seen patients most commonly present with groups of whitish or skin coloured or reddish tiny bumps over sun exposed areas. Larger elevated lesions (plaques) or fluid filled bumps(vesicles) are seen less frequently.

Back of the neck, upper back, chest, outer side of upper arm and forearm are commonly affected sites. Face and hands are less commonly involved as they become tolerant due to exposure to sunlight from childhood.

Why does this skin rash occur?

Exact reason is unknown.

But from various studies and investigations few things are suggested.

I will try to be as simple as possible.

When UVR falls on skin there is some changes that occur on the skin. This change can trigger our immune system and an immune reaction occurs which causes the disease.

Normally when UVR falls on skin it induces an immune suppression which inhibits immune reaction. But in PMLE patients this UVR induced immune suppression is inhibited.

There is some role of genetic and hormonal factors.

But there is some good news

Due to inhibited UVR induced immune suppression patients with PMLE are less susceptible to develop skin cancer. In simple words if you have PMLE then you have less chance of getting skin cancer.

Are there any investigations needed?

Diagnosis is mainly done by taking thorough history and clinical examination.

If there is any confusion or if it needs to be differentiated from diseases like lupus erythematosus then some investigations and biopsy may be required.

Disease course and prognosis

It's a chronic disease which appears intermittently for years. In some cases, the severity decreases with time and may get cured after years. But the prognosis is usually good as many cases are self limiting and in severe symptomatic cases response to treatment is generally very good. In my practice I have seen that most patients get cured only by applying a single cream for few days with adequate photo protection.

Do you need to consult a dermatologist if you have similar skin rash?

Yes of course.

Treatment

Patient counselling and informing the patient with disease course and prognosis is very important because in most of the cases this disease causes enough psychological stress as it mainly occurs over the visible parts of the body.

When a patient presents with PMLE with severe itching firstly symptomatic management to alleviate the symptoms is needed which is done by proper medications which I should not discus here.

Second step is prevention which is done by photo protection. Physical photo protection by using umbrella, hat, protective clothing (like full sleeve shirts for men) are important. Protect your back of the neck with a scarf. For women blouse which covers the whole upper back and chest is very helpful. Along with that proper sunscreen can also be suggested.

Source

1. https://www.ijord.com/index.php/ijord/article/view/92?msclkid=421a9260a6b711ec95844fa6d7c90f4d
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8088173/?msclkid=4219d97ca6b711ecb4af8fed5226bda4
3. Rook’s textbook of Dermatology, 9^th edition, chapter 127
4. Fitzpatrick’s Dermatology, 9^th edition, chapter 92