Behind the bulky term “actinic keratosis” hides an early stage of light skin cancer, the development of which in many cases is due to UV radiation. In particular, rough, scaly skin changes form on sun-exposed areas of the skin. In order to prevent the development of an advanced skin tumor, early treatment of actinic keratosis is important. Various surgical, physical and chemical treatment methods come into question. In any case, consistent UV protection is essential for the cure of actinic keratosis.
What does actinic keratosis mean?
Actinic keratosis (Greek “aktis” for ray) means “cornification disorder caused by radiation”. Synonymously, the terms light keratosis and solar keratosis are used. Do not confuse actinic keratosis with the term “seborrheic keratosis” (senile wart), which refers to a benign and harmless skin tumor.
Definition: what is actinic keratosis?
An actinic keratosis is the initial stage of white skin cancer (squamous cell carcinoma, spinalioma) that is confined to the epidermis (carcinoma in situ) and, unlike advanced (invasive) squamous cell carcinoma, does not invade the deeper layers of the skin. The equally common term “actinic precancerosis” is therefore not entirely clear. This is because, by definition, precancerous lesion refers to a skin change that has an increased risk of degeneration and is therefore merely a precursor of cancer.
Risk factors: Who gets actinic keratosis?
For the development of actinic keratosis, chronic photodamage to the skin from frequent and intense sun exposure is the main risk factor. The number of sunburns is less important than the cumulative UV radiation. Thus, the risk of actinic keratosis increases with age. Men with fair skin types are particularly frequently affected. Other risk factors include chronic immunosuppression – such as after organ transplantation – and infection with certain human papillomaviruses (HPV).
Appearance and symptoms: How do you recognize actinic keratosis?
Typically, actinic keratosis is manifested by rough, scaly patches or flat plaques about five millimeters to one centimeter in diameter that may coalesce into a patchy skin lesion. The color can vary from skin-colored to reddish to yellow-brown. Occasionally, other symptoms occur such as itching, burning as well as pain when touched. Affected skin areas are especially “sun terraces” such as nose, forehead, cheeks, auricles, hairless scalp and arms. On the lip, the condition is called actinic cheilitis. Detect skin cancer – these pictures show how!
Histology ensures diagnosis
If actinic keratosis is suspected, the entire body is usually examined for skin changes – usually with the help of a reflected light microscope. In this process, actinic keratosis can be classified into three degrees of severity (according to Olsen):
- Grade 1 (mild): single reddish spots in millimeter size, better palpable than visible.
- Grade 2 (advanced): whitish keratinized and raised plaques, clearly palpable and visible.
- Grade 3 (severe): thick, warty skin growths.
Five subgroups of actinic keratosis.
In unclear cases, a tissue sample (biopsy) should be taken to rule out advanced spinalioma. Based on histology (microscopic tissue structure), five different subgroups of actinic keratosis can be distinguished:
- Hypertrophic actinic keratosis
- Atrophic actinic keratosis
- Bowenoid actinic keratosis
- Acantholytic actinic keratosis
- Pigmented actinic keratosis
How is actinic keratosis treated?
There are numerous treatment methods for the therapy of actinic keratosis. The treatment decision should be made individually for each patient and depends on various factors such as the number and size of the affected areas of skin, previous diseases, and personal wishes and expectations of the patient. The international guideline recommends classifying patients into four subgroups for the treatment of actinic keratosis:
- Patients with no more than five demarcable skin lesions in one body region.
- Patients with at least six demarcable skin lesions in one region of the body (multiple actinic keratoses)
- Patients with at least six skin lesions in one body region and a contiguous skin area with chronic UV damage and keratinization (field carcinization)
- Patients with additional immunodeficiency (immunosuppression due to medication or disease).
Treatment methods for actinic keratosis
The following is an overview of the various treatment options with advantages and disadvantages. However, not all treatment methods for actinic keratosis are covered by health insurance – it is best to ask your health insurance which costs are covered.
- Surgery
- Icing
- Laser treatment
- Photodynamic therapy
- Chemical treatment
Surgery for individual skin lesions
If only individual areas of skin are affected by actinic keratosis, they can be removed with a scalpel (shave excision) or a sharp spoon (curettage). The removed tissue is then examined histologically – this treatment method therefore also serves to exclude invasive squamous cell carcinoma. Disadvantages include the usual risks of surgery, such as wound infection and scarring.
Icing: Treatment with nitrogen
Icing with liquid nitrogen (cryotherapy) is an effective alternative to surgical treatment of single actinic keratoses. No local anesthesia is required, yet the procedure can be painful. Possible side effects include skin irritation up to blistering and a permanent light discoloration of the treated skin area, since pigment-forming cells can also be destroyed during icing. In addition, no histological examination is possible – therefore, the treatment is not suitable if an invasive skin tumor is suspected.
Risk of infection during laser treatment
Laser treatment is suitable for removing both single and multiple actinic keratoses, as well as for patients with field cancerization. The advantage is that the skin can be ablated over a wide area, so that early skin changes that are not yet visible are also covered (field-directed therapy). However, histological examination is not possible. However, laser therapy can also be painful and also carries the risk of scarring and skin discoloration. In addition, the risk of infection is increased due to the large wound area, which is why laser therapy is not recommended for patients with weakened immune systems.
Photodynamic therapy for multiple actinic keratoses.
In photodynamic therapy, the affected areas of skin are pretreated with 5-aminolevulinic acid or methyl 5-amino-4-oxopentanoate in the form of an ointment or patch. The active substances are absorbed by the tumor cells to a much greater extent than by normal skin cells and lead to increased sensitivity to light of a certain wavelength. After an exposure time of about four hours, the skin is irradiated with a special light source, which leads to the destruction of the affected tissue. Pain, burning and skin irritation may occur. The treatment is particularly suitable for skin affected over a wide area. The risk of recurrence as well as the risk of skin discoloration are said to be lower than with other therapies.
Chemical treatment with ointments and solutions
In addition to the treatment methods described above, there are numerous chemical agents in various forms for topical treatment of actinic keratosis. The preparations can usually be applied at home by the patient himself, but the duration of treatment usually ranges from several weeks to several months. We have compiled an overview of the most important active substances for you:
- Diclofenac in hyaluronic acid gel (Solaraze): the active ingredient diclofenac is said to inhibit the proliferation of cancer cells and is particularly suitable for the face due to its low side effects. However, the treatment lasts at least two to three months.
- 5-Fluorouracil: The active substance is one of the cytostatics and inhibits cell division. The treatment period is several weeks – during which it can sometimes come to quite severe skin irritation. Individual actinic keratoses can alternatively be treated with lower doses of 5-fluorouracil in combination with salicylic acid, which can reduce the side effects.
- Ingenol mebutate: The herbal active ingredient is extracted from the spurge Euphorbia and is suitable for the treatment of smaller skin areas. An advantage is the short application period of two to three consecutive days. The frequently occurring inflammatory reaction of the treated skin usually subsides within two to four weeks without scarring.
- Imiquimod (Aldara, Zyclara): Imiquimod is a so-called immunomodulator, which is also used for the treatment of basal cell carcinoma (basal cell carcinoma) and against genital warts. The active ingredient stimulates the immune defense in the treated skin area, causing an inflammatory reaction that can destroy the tumor cells.
Prognosis: How dangerous is actinic keratosis?
Actinic keratosis differs from the advanced form of cancer in that it does not penetrate the deeper layers of the skin and therefore cannot spread (metastasize). The risk of developing advanced spinalioma within ten years is about ten percent for multiple actinic keratoses and up to 20 percent for field cancers.
Prevention through sun protection
The relapse rate after treatment is reported to be ten to 50 percent, depending on the type of therapy. However, consistent sun protection can significantly reduce the risk of relapse as well as the development of new actinic keratoses. Patients with actinic keratosis should therefore avoid the midday sun and pay increased attention to adequate sun protection: When spending time in the sun, clothing with UV protection, sunglasses, headgear, and sunscreen with SPF 30 or higher are recommended.
