Behind the cumbersome term "actinic keratosis" is an early stage of bright skin cancer, the origin of which is in many cases due to UV radiation. Rough, flaky skin changes are formed especially on sun-exposed areas of the skin.
In order to prevent the development of an advanced skin tumor, early therapy of actinic keratosis is important. Various surgical, physical and chemical treatment methods are possible. In any case, for the healing of actinic keratosis consistent UV protection is essential.
What does actinic keratosis mean?
Actinic keratosis (Greek "aktis" for ray) means "radiation-induced keratinization disorder". The terms light keratosis and solar keratosis are used synonymously.
Not to be confused is actinic keratosis with the term "seborrheic keratosis" (age wart), which refers to a benign and harmless skin tumor.
Defintion: What is an actinic keratosis?
An actinic keratosis is the initial stage of white skin cancer (squamous cell carcinoma, spinalioma), which is limited to the epidermis (carcinoma in situ) and unlike an advanced (invasive) squamous cell carcinoma does not penetrate into the deeper skin layers.
The well-known term "actinic precancerosis" is therefore not entirely clear. Because, by definition, precancerous lesions are a skin lesion that has an increased risk of degeneration and is therefore just a precursor to cancer.
Risk factors: who gets actinic keratosis?
For the development of actinic keratosis the chronic light damage of the skin by frequent and intensive sun irradiation is the main risk factor. It depends less on the number of sunburns, but rather on the cumulative UV radiation. Thus, the risk of actinic keratosis increases with age.
Particularly affected are men with a light skin type. Other risk factors include chronic immunosuppression - such as after organ transplantation - and infection with certain human papillomavirus (HPV).
Appearance and symptoms: How to recognize an actinic keratosis?
Typically, actinic keratosis is characterized by rough, scaly patches or flat plaques of about five millimeters to one centimeter in diameter, which can coalesce into a laminar cutaneous lesion. The color can vary from skin color over reddish to yellow-brown.
Occasionally, other symptoms such as itching, burning, and pain on touch may occur. Affected skin areas are especially "sun terraces" such as nose, forehead, cheeks, auricles, hairless scalp and arms. At the lip the disease is called actinic cheilitis.
Histology ensures diagnosis
If actinic keratosis is suspected, the entire body is usually examined for skin lesions, usually with the aid of a reflected-light microscope. The actinic keratosis can be divided into three degrees of severity (Olsen):
- Grade 1 (mild): Individual reddish patches in millimeter size, more palpable than visible
- Grade 2 (advanced): whitish cornified 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 exclude an advanced spinal instinct. On the basis of histology (microscopic tissue structure), five different subgroups of actinic keratosis can be distinguished:
- hypertrophic actinic keratosis
- atrophic actinic keratosis
- bowenoid actinic keratosis
- akantholytic actinic keratosis
- pigmented actinic keratosis
How is actinic keratosis treated?
For the treatment of actinic keratosis, there are numerous treatment methods. The treatment decision should be made individually for each patient and is dependent on various factors such as the number and size of the affected areas of the skin, pre-existing conditions and the patient's personal wishes and ideas.
The international guideline recommends classifying patients into four subgroups for the treatment of actinic keratosis:
- Patients with a maximum of five definable lesions in one body region
- Patients with at least six definable lesions in one body region (multiple actinic keratoses)
- Patients with at least six skin lesions in one body region and one contiguous skin area with chronic UV damage and keratinization (field cancerization)
- Patients with additional immunodeficiency (immunosuppression due to medication or illness)
Treatment with actinic keratosis
The various treatment options with advantages and disadvantages are presented below. However, not all treatments of actinic keratosis are cash benefits - check with your health insurance company best what costs are covered.
- ice up
- laser treatment
- photodynamic therapy
- chemical treatment
Surgery for individual skin changes
If only individual skin areas are affected by actinic keratosis, they can be removed with a scalpel (shave excision) or a sharp spoon (curettage).
Subsequently, the removed tissue is histologically examined - this treatment method therefore also serves to exclude an invasive squamous cell carcinoma.
Downside are the usual risks of surgery such as wound infection and scarring.
Icing: treatment with nitrogen
Freezing with liquid nitrogen (cryotherapy) is an effective alternative to the surgical treatment of single actinic keratoses. No local anesthesia is necessary, but the procedure can be painful.
Possible side effects include skin irritation to blistering and permanent bright discoloration of the treated area of the skin, as icing can destroy pigment-forming cells.
In addition, no histological examination is possible - therefore, the treatment is not suitable if there is a suspicion of an invasive skin tumor.
Infection risk during laser treatment
Laser treatment is suitable for both single and multiple actinic keratosis and for patients with field cancer.
The advantage is that the skin can be removed over a wide area, so that even early skin changes that are not yet visible can be detected (field-directed therapy). However, histological examination is not possible.
However, the laser therapy can be painful and also carries the risk of scarring and discoloration of the skin.
In addition, the risk of infection is increased due to the large wound area, which is why laser therapy is not recommended in patients with weakened immune systems.
Photodynamic therapy for multiple actinic keratoses
In photodynamic therapy, the affected areas of the skin are pretreated with 5-aminolevulinic acid or methyl 5-amino-4-oxopentanoate in the form of an ointment or patch. The drugs are absorbed by the tumor cells far more than normal skin cells and result in increased sensitivity to light of a particular wavelength.
After a contact time of about four hours, the skin is irradiated with a special light source, which leads to the destruction of the affected tissue. This can cause pain, burning and skin irritation.
The treatment is particularly suitable for surface affected skin. The risk of relapse and the risk of skin discoloration should be lower than with other therapies.
Chemical treatment with ointments and solutions
In addition to the described treatment methods, there are numerous chemical agents in various forms for topical treatment of actinic keratosis.
The preparations can usually be used at home by the patient, but the duration of treatment is usually several weeks to several months. We have compiled an overview of the most important active ingredients 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 the low side effects. However, the treatment lasts at least two to three months.
- 5-fluorouracil: The active ingredient is one of the cytostatic agents and inhibits cell division. The treatment time is several weeks - during which it can sometimes come to quite strong skin irritation. Individual actinic keratoses may alternatively be treated with lower dose 5-fluorouracil in combination with salicylic acid, which may reduce side effects.
- Ingenol mebutate: The herbal active ingredient is extracted from the euphorbia milkweed and is suitable for the treatment of smaller areas of the skin. One advantage is the short duration of two to three consecutive days. The frequently occurring inflammatory reaction of the treated skin usually ceases without scar within two to four weeks.
- Imiquimod (Aldara®, Zyclara®): Imiquimod is a so-called immunomodulator, which is also used to treat basal cell carcinoma (basalioma) and against genital warts. The active substance stimulates the immune defense in the treated skin area, which leads to 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 can not scatter (metastasize).
The risk of developing an advanced spinal instability within ten years is around ten percent for multiple actinic keratoses and up to 20 percent for field cancer.
Prevent from sunscreen
The rate of relapse after treatment is given as 10 to 50 percent depending on the type of therapy. Through consistent sun protection, however, the risk of relapse and the emergence of new actinic keratoses can be significantly reduced.
Patients with actinic keratosis should therefore avoid the midday sun and pay more attention to adequate sun protection: For sun exposure, UV protection, sunglasses, headgear and sunscreen with SPF 30 or higher are recommended.