Actinic keratosis

definition

The term actinic keratosis describes a precancerous stage in need of therapy (Precancerous disease) of the skin caused by chronic exposure to sunlight (UV light) is triggered. It is about the multiplication (proliferation) atypical skin cells (Keratinocytes) in the area between the dermis (Dermis) and the epidermis (epidermis) which manifests itself as a cornification disorder. The keratosis can turn into squamous cell carcinoma.

frequency

Fair-skinned, blue-eyed people (people with skin types I and II) who are permanently exposed to the sun have a significantly increased risk of developing actinic keratosis.

Darkly pigmented people, on the other hand, have little risk of developing actinic keratosis. Men are more often affected by the disease than women.

Occupational groups such as seafarers, road workers, construction workers and farm workers are particularly vulnerable because of the long exposure to the sun. According to an American study, the relative frequency of illnesses (prevalence) in those over 20 years of age is 11% and 25% in those over 30 years of age. A British study found a risk of 15% for those over 40 years of age. Up to 10 million people in Germany are affected by actinic keratosis. In Australia, on the other hand, the prevalence of those over 40 is 45%.

In addition, the number of new cases (incidence) in Europe has increased significantly in recent decades due to the increasing frequency of travel to countries with higher levels of UV radiation and the longer exposure to the sun due to leisure activities, as well as higher environmental UV radiation. As a result, the term senile keratosis is a bit out of date, as many young people nowadays also get sick who spend too long in the sun or go to the solarium, for example.

People who are exposed to permanent suppression of the immune system (immunosuppression), as is the case, for example, after an organ transplant, also have a significantly increased risk of disease. But also diseases such as albinism, Rothmund-Thomson syndrome, Cockayne syndrome. Xeroderma pigmentosum and Bloom's syndrome represent a genetic predisposition to develop actinic keratoses.

Causes of Actinic Keratosis

Permanent changes (mutations) caused by UVB rays develop after 10 to 20 years on chronically light-exposed skin cell clones of abnormal (atypical) cells, which irreversibly damage their DNA (Heritage) exhibit. These altered cells slowly penetrate the normal epidermis and lead to the loss of proper layering of the skin and cornification disorders. The actual repair system of the skin cannot prevent the formation of the pathologically altered skin cells in the case of permanent solar radiation or high UV radiation.

The so-called telomerase gene and the tumor suppressor gene TP53 are affected by these mutations. These genes are proteins that control the cell cycle or trigger the cell death of atypical cells (apoptosis). If their function is switched off by changes in the genetic make-up (mutations), the malignant cells can develop. Furthermore, the changes can also affect the tissue below the epidermis, in the dermis (Dermis) spread. If the basement membrane between the epidermis and dermis is broken, one speaks of an invading tumor, an invasive squamous cell carcinoma, which develops in 5-10% of patients. Actinic keratosis thus represents an early stage of cancer (Carcinoma in situ) represent.

But not only the UVB rays of the sun with a length of 280-320nm can trigger actinic keratosis. Forms of electromagnetic radiation such as UVA light, such as is used in the therapy of psoriasis, ionizing radiation or infrared radiation can also trigger the disease.

Degrees of actinic keratosis

Actinic keratosis can be divided into different degrees and types. The grading according to Olsen classifies actinic keratosis according to its clinical appearance. This means that the appearance and the texture of the skin changes are used as classification criteria. There are three degrees according to Olsen, which are explained in more detail in their own sections (see below). Another classification is the differentiation of histological subtypes. This classification differentiates actinic keratoses with regard to their tissue properties. For this classification, a skin sample must be examined under a microscope. There are 6 histological subtypes.

Grade 1

Actinic keratoses are categorized into grade 1 according to Olsen at the stage in which they become visible at the earliest point in time. They are mild actinic keratoses. Their appearance is faintly reddish and spotty. Usually they are easier to feel than nodular structures. You can see individual or a few incoherent skin changes that are blurred. With a size of only a few millimeters, they are often overlooked.

Grade 2

Moderate actinic keratosis is class 2 according to Olsen. The appearance of this stage is clearer and easier to recognize than with grade 1 according to Olsen. There is whitish or reddish discoloration of the skin that may be flaky. This is due to excessive keratinization (Hyperkeratosis) conditions. The skin feels rough and nodular indurations may be palpable. A brown discoloration of the skin is also possible. Usually several areas of the so-called "sun terrace" are affected. These include the forehead, the bridge of the nose and the scalp as well as the cleavage.

Grade 3

A grade 3 according to Olsen is determined in severe actinic keratosis. These are advanced skin changes that require action. Thick, wart-like skin changes are visible and palpable. Brown and white discoloration is also typical. The skin changes are firmly attached to the subsurface and cannot be peeled off or scratched off. The transition to white skin cancer is fluid at this stage. Bleeding of the skin changes is possible on contact.

Early stage / initial stage of actinic keratosis

Actinic keratosis develops slowly and is basically not noticed by those affected. Recurring exposure to UV radiation, be it from extensive sunbathing or visits to the solarium, work outdoors or frequent sunburns in childhood, lead to permanent damage to the skin cells and ultimately to cancer precursors or early forms. This process takes place over several years, so that visible changes are usually only present in old age. In this sense, very early forms cannot be seen at all - the cell changes take place in the non-visible area, so to speak.

The first visible changes, which could be described as early or early stages, are usually red, blotchy skin appearances. These can be very inconspicuous and are initially overlooked, especially with slightly darker skin types. Usually the changes in the early stages of actinic keratosis are better to feel than to see a kind of small nodule. However, those affected often do not notice this very much. Changes on the scalp, a common localization of actinic keratosis, are neglected.

Actinic Keratosis Symptoms

Actinic keratoses are mainly found in areas that are exposed to increased light, i.e. the forehead or a bald head, auricles, cheeks, the bridge of the nose, lower lip, forearms or the back of the hand. Single or multiple foci can appear at once, which can have a diameter of 1 mm to 2.5 cm.

At first there are sharply demarcated, round or oval reddened foci with a rough surface, this is the erythematous type of actinic keratosis.

In the course, the increased cornification (hyperkeratosis) more pronounced, and yellowish dirty brown thickened keratosis develops, this is the keratotic type.

Experts speak of a cornu cutaneum type if there is a very strong horn formation. Furthermore, the pigmented type can be distinguished, in which there is increased or decreased skin coloration (pigmentation).

In the area of ​​the lips, the cornification disorder is known as actinic cheilitis. As a rule, the patients are symptom-free, sometimes a feeling of tension, burning or itching can be felt. In addition to pigmentation disorders, telangiectasias also occur, which are enlarged skin vessels that become more prominent in the affected area.

Pedilection agencies

Actinic keratosis of the nose

The nose is a common location for actinic keratosis. The bridge of the nose in particular is often affected. This has the following reason: The bridge of the nose is one of the so-called sun terraces of the skin. These are areas of the skin that are particularly exposed to solar radiation. As a protruding bony structure, the bridge of the nose is more exposed to sunlight than, for example, the lower back. The nose is also often simply forgotten when sunscreen is applied, as is the back of the hand and foot.

Furthermore, the nose is not protected by clothing, as is the case with other skin regions. Actinic keratoses therefore often develop on the nose. However, the type of skin changes does not differ from other skin areas and is treated in the same way. The nose can show individual or continuous, flat skin changes. The extent of the actinic keratoses then ultimately determines the therapy. Extensive cutting out of the skin changes is often problematic on the nose, so that treatment with ointments and gels is often preferred in the case of extensive infestation. Photodynamic therapy is also very suitable, as the cosmetic result on the nose is particularly satisfactory.

Actinic keratosis on the lip

Actnic keratosis is a special form and is also called actinic cheilitis designated. It is an inflammation of the lip surface provoked by UV light. Usually the lower lip is affected. Furthermore, men are more likely than women to have actinic keratosis on the lip. An important risk factor for the appearance of actinic keratosis on the lips is smoking. It is often a combination of damage resulting from UV and tobacco exposure. The chronic form of actinic cheilitis is to be understood as a precancerous stage and can be treated with various therapy options. In the case of a slight expression without flaky deposits, care measures with greasy and light-protecting lipsticks are usually sufficient. A stronger expression requires treatment.

Actinic keratosis on the scalp

The scalp is one of the most common sites for actinic keratosis because it is often exposed to sunlight. Bald people in particular need to have good sun protection for their scalp. However, this is all too often neglected. Over the years, changes in the form of actinic keratosis occur, which are easily overlooked at the beginning. Individual skin changes can be removed with procedures such as freezing, surgery, or laser excision. In the case of extensive scalp involvement, treatment with ointments or photodynamic therapy is preferable.

diagnosis

The diagnosis is usually made clinically, i.e. based on the symptoms and the visible and palpable findings on the skin.

To confirm the diagnosis, a Skin sample (biopsy) can be removed and examined pathologically and histologically. Also can through a Reflected light microscope with the help of a skin sample a differentiation from other skin diseases, such as seborrheic keratoses be made.

Actinic Keratosis Therapy

Actinic keratosis is a precursor or early form of light skin cancer and must therefore be taken very seriously as such. Therefore, early therapy is very important. Various approaches are available for treating actinic keratosis. An experienced dermatologist can explain the various therapy options. In the following section, the most important therapy options are clearly presented and explained in more detail with regard to their implementation:

• Lesion-oriented therapy with liquid nitrogen / cryosurgery: Small skin changes can be frozen with liquid nitrogen under local anesthesia. This procedure is also known as cryosurgery.
• Surgical removal: Actinic keratoses can also be surgically removed under local anesthesia. The removed material is then examined in more detail in order to identify precancerous or cancerous diseases and classify them more closely.
• Removal using laser therapy: With the help of a laser, the uppermost layers of the skin that are affected by changes can be destroyed. In this way, the underlying tissue is spared.
• Curettage: The curettage is a treatment in which the changed skin material is scraped off with a so-called "sharp spoon" (curette). This treatment is also carried out under local anesthesia. The material obtained is examined further after the treatment.
• Field therapy with surface-active substances: When large areas of the skin are affected by actinic keratosis, one speaks of one Field cancerization. In this case it is not possible to remove all altered areas of the skin. Therefore, ointments, creams or gels with substances that have a flat effect are applied. These include cytostatics, immunosuppressants, and anti-inflammatory substances that are applied over several weeks. Frequently used substances are imiquimod, 5-fluorouracil or diclofenac.
• Photodynamic therapy: Photodynamic therapy is also a procedure that achieves good results when the skin is affected over a large area. It does not leave any scars and therefore gives cosmetically satisfactory results. First, an ointment is applied that contains a dye-like substance. The skin is then irradiated with a cold red light. The treatment can be repeated after a few months.

Further information on the subject can be found here: Actinic Keratosis Therapy

Icing over

In the case of selective changes in the skin, there is the possibility of icing the affected areas with liquid nitrogen. This procedure is also known as cryosurgery. The cold destroys the changed skin cells and is therefore suitable for the treatment of pre-cancerous stages. A distinction is made between two processes, namely the spray and the contact process. With the open spray method, the liquid nitrogen is sprayed onto the changed skin. In this way, tissue can be destroyed up to a depth of 12 mm. However, there is also the option of placing a probe or a pre-cooled metal stamp directly on the actinic keratoses. This is known as the contact procedure. The treatment can usually be carried out on an outpatient basis under local anesthesia and is gentle on the patient.

Therapy with an ointment?

In the treatment of actinic keratosis, a distinction is made between “lesion-oriented therapy” and “field therapy”. "Field therapy" is used when large areas of the skin are affected by the changes. Another reason is the treatment of skin areas in which changes in the cells already exist but are not yet visible. One possibility for "field therapy" is treatment with an ointment, cream or gel. Such ointments contain anti-inflammatory substances, antivirals or cytostatics. Cytostatics kill cancer cells or their precursors and are therefore very suitable for therapy. Antivirals are agents that fight viruses.

Some substances, such as imiquimod, achieve very good results in the treatment of actinic keratosis and are therefore used very widely. Other important active ingredients are 5-fluorouracil and diclofenac. The substances are applied to the skin over several weeks following a treatment scheme and do not leave any scars. Apart from the cosmetic result, a great advantage for the patient is that skin areas that do not yet show any visible changes are also treated. The risk of a relapse, i.e. a relapse, is reduced in this way.

Is the therapy a health insurance benefit?

Since actinic keratosis is a disease that requires treatment, the costs for a therapy are borne by the health insurance companies. This applies at least to classic forms of treatment, such as freezing, surgical removal or therapy with locally acting substances.

Unfortunately, the costs for photodynamic therapy are not covered by every health insurance company. Whether photodynamic therapy is borne by the health insurance company depends on the individual insurance benefits and the respective case. It is therefore advisable to talk to the health insurance company before undertaking such treatment.

Homeopathic Therapy

A homeopathic treatment of actinic keratosis can only be strictly discouraged at this point. Actinic keratosis is an early form of white skin cancer which, if left untreated, can progress. The consequences of advanced cancer are potentially fatal. Therefore, homeopathic treatments are not recommended.

forecast

Will the actinic keratosis Discovered and treated in good time, there is generally a good prognosis. Otherwise it can result in a carcinoma, So a Spinalioma or Squamous cell carcinoma develop. It is also possible, for example, that the disease will recur (relapse) after treatment with PDT. For this reason, follow-up checks should be carried out continuously.

prophylaxis

The most effective prevention has proven to be complete Avoidance of UV light (Parental leave) with the help of hats, UV-impermeable clothing and sunscreen, as well as an adapted leisure behavior. 25% of actinic keratoses even heal without treatment when there is no UV light. You should also regularly examine your skin for abnormal areas and if possible one Skin cancer screening examination (Screening).