INTRODUCTIONPhotosensitivity occurs when someone experiences an abnormal skin reaction after "normal" exposure to sunlight or other light sources, such as a tanning bed or incandescent light bulbs. Several conditions involve photosensitivity.
Polymorphic Light Eruption
(PLE) is the most common of these conditions. Polymorphic Light Eruption (PLE) or "sun allergy" is the most common. "Polymorphic" means "occurring in various forms." "Eruption" means a skin rash. PLE, therefore, refers to several abnormal skin reactions that occur after exposure to (sun)light. This information will primarily focus on PLE. It will not discuss the "normal" skin reactions that everyone experiences after (too) long-term exposure to (sun)light. These can include a sunburn reaction, tanning, premature skin aging, and possibly some forms of skin cancer. PLE occurs equally in men and women, regardless of age. PLE occurs more often in patients with fair skin. It usually begins in young adulthood.
Internal diseases
Internal diseases are sometimes accompanied by a hypersensitive skin reaction to sunlight. Lupus erythematosus is the most common example. There is a form of lupus erythematosus with only skin lesions and a form with additional symptoms in other organs (particularly joints). Porphyria occurs when there is an excess of porphyrins in the blood. These are the building blocks of hemoglobin (the blood pigment in red blood cells). If something is wrong with the production of hemoglobin, these building blocks can accumulate in the blood. This causes sunlight sensitivity with blisters and very thin, fragile skin on the face and the backs of the hands.
Medications
Certain medications can make the skin hypersensitive to sunlight. Tetracycline is a well-known example. With some medications, you see irritated skin, similar to a sunburn, while with others, you get a more itchy, allergic reaction similar to PLE.
Plants
Contact with plants can also cause an abnormal reaction to sunlight. The most striking example is the reaction caused by hogweed. If the skin is exposed to sunlight after contact with hogweed, blisters will develop.
Cosmetics
, ointments, mosquito bite remedies, and even sunscreens can cause sun sensitivity. Ointments prescribed by a doctor can also occasionally cause sun sensitivity.HOW DOES IT COME ABOUT?PLE is caused by light. Whether other factors also play a role is currently unknown.
Sunlight consists not only of visible light but also of ultraviolet (abbreviated: UV) light, which we cannot see. UV light is divided into (short-wave) UVB and (long-wave) UVA, both of which largely cause the "normal" skin reactions mentioned earlier. UVA is currently considered the primary cause of PLE.WHAT ARE THE PHENOMENA?The most common skin lesions are very itchy, small bumps on light-exposed areas of the skin, such as the face, neck, backs of the hands, forearms, and lower legs. Blisters, redness, swelling, and scaling are also sometimes seen. The skin reactions can spread to unexposed areas of the skin. A small number of patients experience itching symptoms consistent with PLE, even though there are no visible skin reactions.
The skin reactions can occur "spontaneously" at any time, even when previously the patient was quite tolerant to the sun. They develop approximately one day (sometimes up to 5 days) after exposure to (sun)light and are usually not preceded by a sunburn reaction. Without further exposure to sunlight, the skin lesions heal within 7 to 10 days.HOW IS THE DIAGNOSIS MADE?Whether the reactions are caused by UVB or UVA can be determined fairly accurately by answering the following questions. Do the skin reactions occur:
- also behind glass
- also in the shade
- also despite sunscreen
- also during partly cloudy conditions
? Four "yes" means it is probably UVA. Four "no" answers indicate UVB.
A dermatologist can usually diagnose PLE based on the patient's history and the observed skin reactions. Occasionally, it is necessary to use light tests to determine whether UVA, UVB, or visible light is causing the skin reactions. However, there is no test that can definitively diagnose PLE. These light tests can also detect other light-induced skin conditions. It can also be investigated whether certain substances (cosmetics, medications, etc.) cause a hypersensitivity reaction in combination with light (photopatch tests).
In addition, laboratory tests can be performed on blood, feces, urine and/or a piece of skin ( biopsy ) to rule out certain diseases, such as lupus erythematosus and porphyria.WHAT IS THE BEST TREATMENT?Light Acclimatization
For mild forms of PLE, gradually acclimatizing the skin to sunlight in the spring is sufficient. This can be achieved by considering when and where sunlight is most intense. This results in gradual light acclimatization. During the first few weeks, a good sunscreen (sunscreen) can be used. This should have a high SPF.
Sunscreens
For severe forms of PLE, sunscreens are of limited value, as most only protect against UVB. Even so-called sunblockers likely provide only partial protection against UVA, while UVA is so important for PLE. A worsening of the condition could even occur because the normal sunburn reaction caused by UVB barely occurs during the use of sunscreen, causing the patient to stay in the sun longer and thus increase their exposure to UVA.
PUVA Therapy and UVB Therapy:
A dermatologist can induce gradual light adaptation by applying a form of light therapy (PUVA or UVB therapy). This involves exposing the skin to a special artificial light source two to three times a week for several weeks every spring or before a vacation. With PUVA therapy, the patient must take certain medications (psoralens) two hours before each radiation treatment, which make the skin more sensitive to light. PUVA stands for psoralens plus UVA. Glasses must be worn on the day of the treatment to protect the eyes. No medication is required for UVB treatment.
Antimalarials:
Another treatment option is taking antimalarials. These medications were first used for malaria, but are now also used for several skin conditions involving photosensitivity, such as PLE.
Other Treatment Forms:
Beta-carotene is also sometimes used for PLE. However, its effect is questionable.
WHAT CAN YOU STILL DO?- Stay out of the sun, especially between 11:00 AM and 3:00 PM when the sun is at its strongest.
- Wearing loose-fitting clothing with long sleeves and a wide-brimmed hat or cap provides good protection from the sun.
- Keep in mind that the wind has a cooling effect, making the sun less noticeable.
- The sun's effect is greater when sitting or lying still than when moving.
- Wet skin is more sensitive to sunlight.
- Snow and sand reflect a lot of sunlight; water and grass reflect very little.
- Even under a parasol, a lot of sunlight (particularly UVA rays) reaches the skin.
- Behind glass, UVA rays reach the skin, but not UVB rays.
- Even in cloudy conditions, a lot of sunlight reaches the earth.
- In high mountains, more sunlight (particularly UVB rays) reaches the earth.
- Sunscreens, or better yet, sunscreens, protect mainly against UVB rays and little against UVA rays. For very sensitive skin, a product with a high SPF should be used.WHAT ARE THE OUTLOOK?In 30% to 50% of patients, symptoms begin each spring and disappear with repeated exposure to sunlight during the summer. This is called photoacclimatization. This acclimatization to (sun)light disappears again in the winter. In severe cases, reactions persist after each exposure to (sun)light. Generally, PLE persists for years. Sometimes it worsens over the years, sometimes it improves spontaneously. |
