Actinic keratoses (solar keratoses)

Actinic keratoses, or solar keratoses, are the most common sign of sun damage on the skin for all fair-skinned individuals.
They are referred to as actinic keratoses because the real cause of their appearance on the skin is exposure to all ultraviolet (UV) rays, not just those from the sun but also those from UV lamps. Actinic keratoses appear as single or multiple lesions, and their appearance can vary considerably.
They will only form on skin that has been exposed to UV rays.

In its most common form, actinic keratoses are small areas of skin that are always reddened, rough to the touch and flaky, with scales that peel off and reform.
Actinic keratoses are usually itchy and are multiple in number.
However, a single, large actinic keratosis patch may also appear.

No matter the size, the clinical features are the same: permanent redness and continuous desquamation.
Actinic keratoses may be densely scattered over an area of photodamaged skin such that it is difficult to recognize them as single element(s).

Actinic keratoses can appear in any part of the skin that has been damaged by the sun or UV lamps.
The most affected sites are the face, the scalp (in bald individuals), the backs of the hands and forearms, the front of the legs, and the upper part of the trunk. The scalp is normally protected by the presence of hair but if the individual is bald, the scalp is particularly vulnerable to radiation from UV rays.

Particularly scaly and troublesome actinic keratoses form that are often scattered across the zone.
Actinic keratoses appear on the back of the hands especially in fair-skinned individuals who are also prone to solar lentigines.

The dorsal side of the forearm is also an area that receives a lot of solar radiation especially in outdoor work.

The leg can also be an area where numerous actinic keratoses form, specially in those who often wear shorts or skirts, or for those who enjoy suntanning.

For sun worshippers, the upper part of the trunk is also vulnerable to strong UV irradiation, and numerous actinic keratoses associated with the other signs of chronic photodamage can also form here.

UV rays

Ultraviolet (UV) radiation is invisible to the naked eye and does not carry heat so it’s completely undetectable without the use of specialized equipment.
Despite the fact the rays cannot be perceived, they are packed with great electromagnetic energy.
When this energy – be it from the sun or a UV lamp – impinges on the cells of the skin, it causes damage such as the break up of the DNA chain of cells as shown below.

While the DNA will likely later be repaired, it is possible that some UV-damaged cells will be only partially repaired, causing abnormalities such as actinic keratoses.
The evolution of an actinic keratosis to spinocellular epithelioma is very likely, especially in cases where timely intervention is not taken and UV exposure continues.

Action should, therefore, be taken on actinic keratoses for several reasons:

• to prevent evolution into spinocellular epithelioma;
• to reduce physical discomfort (itching, dryness);
• to reduce cosmetic damage (sense of premature skin aging);
• to raise awareness of safe sun exposure

Treatment options

Treatment options for actinic keratoses are:

• Radical surgery
• Curette surgery or curettage
• Thermal procedures (laser therapy, diathermocoagulation, cryotherapy)
• Topical chemotherapy (5-fluorouracil)
• Topical immunotherapy (imiquimod)
• Topical pharmacotherapy (diclofenac)
• Ingenol mebutate
• Photodynamic therapy (PDT)

Radical surgery may be the preferred treatment option when there is a single lesion or there is recurrence from previous therapies. As surgery leaves scars, it is not often used in particularly visible areas, such as the face.
Curettage can be considered but may leave permanent hypopigmentation (white spots).
Thermal destruction also results in hypopigmentation and has a high rate of recurrence.
Topical chemotherapy with 5-fluorouracil is unsafe, results in hypopigmentation and has a high rate of recurrence.
Topical immunotherapy with imiquimod gives inconsistent results, causes considerable inflammation, and is an expensive, time-consuming option.
Topical pharmacotherapy with diclofenac gives inconsistent results and has a high rate of recurrence.

Photodynamic therapy

Photodynamic therapy (PDT) is now the treatment of choice for the various forms of actinic keratoses. Among the various forms of photodynamic therapy, the most widely practiced uses 5-aminolevulinic acid (ALA). The therapy is therefore referred to as ALA-PDT. ALA-PDT leverages on the photodynamic phenomenon, whereby chronically UV-injured cells absorb ALA and internally transform it into protoporphyrin IX. When the skin is then exposed to 630 nm light (red light) or sunlight, protoporphyrin IX releases energy which in turn generates unstable oxygen species called ROS. ROS then oxidizes lipids and proteins blocking the metabolism of the cell. The cell subsequently dies and will be replaced by a healthy one.

ALA-PDT for actinic keratoses: an overview

• Selection of the patient to be treated
• Detailed information given about the method
• Informed consent received
• Preparation of the area to be treated with the sulfosalicylic 2S Cream in order to remove excess scales. 2S Cream should be applied each evening for at least ten days
• Application of 10% ALA in PEG Ointment to the area to be treated
• Covering the area with polyethylene film to promote absorption
• Additional coverage with gauze and plaster to keep the dressing in place and prevent light from passing through
• Waiting for two hours to enhance the synthesis of protoporphyrin IX (*)
• Illumination with 630 nm light source for the time required to administer approximately 100 J x cm 2 (usually ten minutes)
• Dressing at the end of treatment with PEG Ointment to be continued into the following week
• After 30 days, repeat with a new session of ALA-PDT (**)
• Provide recommendations for physical photoprotection (hat, glasses, t-shirt, Sun Clay)
• Clinical checkup at a time to be determined (***)

(*) (**) (***) exposure times, number of ALA-PDT sessions and timing for follow-ups are determined by the dermatologist depending on parameters such as degree of photodamage, number and type of actinic keratoses, site to be treated, activity of the subject, etc.

• Once the skin has fully healed, the micropeeling Face Glycocream or the vaseline-free, sulfosalicylic 2S Cream can be used to maintain results. As a sunscreen, apply the mineral photoreflector, Sun Clay.

The following are examples of the results obtained with PDT in cases of Actinic Keratosis:

Prevention

Actinic keratoses can be prevented by early sun exposure education. However, if they have already appeared and have been treated, particularly strict safe sun exposure must be followed. In addition to a hat, dark sunglasses and a t-shirt, it is important to cover any remaining exposed skin with the mineral photoreflector, Argillina Sole, which gives more guarantees than sunscreen. While the latter exhausts its protective properties as soon as its chemical filters wear off, mineral reflectors continue their protective action right up until they are washed off.
An important principle to remember is that the skin should never, or almost never, be exposed to direct sunlight. A sun hat, sunglasses and clothing provide safe sun protection, with Argillina Sole covering any remaining skin that is exposed.