The reports about how getting too much sun is bad for you are everywhere these days. So, unless you’ve been living in a cave — and if you have, then you don’t have to worry about sun exposure — you probably already know excess sun can cause skin problems. Some of the better-known issues are those that affect a person’s appearance. These range from freckles and dark spots to wrinkles and premature aging. However, there are other, more serious effects that can crop up that people are less aware of. Actinic keratosis is one of these.
WHAT IS ACTINIC KERATOSIS?
Actinic keratosis consists of scaly, rough, often raised patches on the skin. They often show up on surfaces with a history of continuous sun exposure, so it’s common to find them on the face, the scalp, the neckline, the back of the hands, and the legs or arms. These patches are usually smaller than a cm. It’s common for several of them to appear in the same area, and they may merge to form larger lesions. The spots can be brown, pink, or red, with the look of a dry crust and possibly hard to the touch. The skin around the patches can be red and inflamed.
Excessive exposure to solar radiation, which is composed of visible and invisible radiation, is the main cause of actinic keratosis. The invisible fraction of light, represented by ultraviolet A (UVA) and ultraviolet B (UVB) rays, causes the cells that form the most superficial layer of skin to lose their ability to repair themselves and to grow abnormally. Actinic keratosis is one of the most frequent reasons people see a dermatologist. Although excessive sunlight exposure is the main culprit, other factors can make people more susceptible to developing actinic keratosis. These include being Caucasian, having fair skin, having light eye colors, being over age 50, and having suffered a severe sunburn at an early age.
IS ACTINIC KERATOSIS A SERIOUS ISSUE?
It can be. In some cases of actinic keratosis, the lesions go away by themselves thanks to the person’s immune system. However, this usually only happens in younger people. For everyone else, the patches either remain the way they are or, in a small percentage of cases, develop into carcinoma, a type of invasive cancer. Although the risk of progression of actinic keratosis to cancer is low, the best preventive measure is to detect it as early as possible and then treat it.
HOW CAN ACTINIC KERATOSIS BE TREATED?
When treating actinic keratosis, the primary objective is to eliminate the lesions so as to minimize the possibility of their progression to cancer, but an added goal is to improve the patient’s aesthetic appearance.
Surgical removal is one treatment possibility. Cryotherapy and CO2 laser are ablative treatments, meaning they are designed to physically destroy the lesions. Topical treatments, where an active ingredient such as ingenol mebutate, diclofenac with hyaluronic acid, or fluorouracil is applied to the skin, are another option.
The other alternative is photodynamic therapy, or PDT. It’s very effective, with a high cure rate, and doctors often chose it when the patient cares a great deal about the cosmetic aspect of the treatment result. It also has the advantage of having been shown to be preventive by reducing the appearance of new lesions. The main limitation of PDT is that patients sometimes report pain as a side effect, but this can be minimized by moistening the area or administering local anesthesia.
The most appropriate treatment depends on patient-related factors and on the doctor’s expertise and familiarity with the various therapies. PDT is a complex procedure, but there is little doubt about its efficacy and its aesthetic benefits.
PHOTODYNAMIC THERAPY WITH AMINOLEVULINIC ACID
Photodynamic therapy consists of the administration of a photosensitizing agent to the actinic keratosis lesions. The treatment area is covered, for anywhere from three to 18 hours, with a dressing that blocks all light. The area is then uncovered and subsequently illuminated with a certain type of light.
PDT works because this photosensitizing agent, when activated by light, causes a photooxidation process. This means that the agent and the light react and create a specific kind of oxygen molecule. This process results in the death of the keratosis cells. In this case, the photosensitizing agent is aminolevulinic acid.
Aminolevulinic acid is a medication in gel form used to treat mild to moderate actinic keratosis. As a photosensitizing substance, it will change when it is exposed to light of a particular wavelength. Application of aminolevulinic acid to the actinic keratosis lesions results in an accumulation of molecules called porphyrins. Exposure to light causes these porphyrins to activate and react to form toxic, oxygen-containing molecules called free radicals. These free radicals cause irreversible damage to the keratosis cells, and they ultimately die. The body reacts with a localized inflammatory reaction which eliminates the dead cells, and this, in turn, stimulates cell regeneration in the area.
HOW IS PDT CARRIED OUT?
PDT requires special lamps which will act as the light source that activates the aminolevulinic acid. A dermatologist with experience with the PDT technique is the one who will perform or supervise the treatment. She starts by carefully scraping the actinic keratosis patches to gently remove any crusts or scales. Then, she applies a layer of the aminolevulinic acid gel on the lesions. It is left to dry for about ten minutes, and then it’s covered with an opaque dressing for a prescribed number of hours. The doctor then removes the dressing and washes the zone to eliminate any gel that remains. She then exposes the treatment area to light using an appropriate lamp for around 10 to 15 minutes.
Two to three months post-treatment, the doctor will evaluate the condition of the lesions to decide if a second photodynamic therapy session is warranted for any lesions that might remain.
PDT with aminolevulinic acid represents a viable choice for the treatment of actinic keratosis. Side effects occur infrequently, studies back up its efficacy, and importantly, it leads to good cosmetic outcomes. Preventive measures like limiting sun exposure and using sunscreen remain, of course, the best option of all.