Actinic Keratosis: Causes

Pathogenesis (disease development)

In actinic keratosis (AK), cumulative UV exposure causes mutations (genetic changes) in skin cells and proliferation (growth) of atypical keratinocytes (horn-forming cells). This process initially takes place in the area of the basement membrane, so that actinic keratoses are regarded as carcinoma in situ (literally: “cancer at the site of origin”) for squamous cell carcinomas.

The risk of progression is reported to be up to 16% per year. In up to 10% of cases, actinic keratosis develops into squamous cell carcinoma of the skin within 10 years (synonyms: cutaneous squamous cell carcinoma (SCC); spinalioma; spinocellular carcinoma; spiny cell carcinoma).

Etiology (causes)

Biographic causes

• Genetic burden
  • Genetic diseases
    • Albinism – genetic disorder with autosomal recessive inheritance or collective name for congenital disorders in the biosynthesis of melanins and the resulting lighter skin, hair and eye color.
    • Bloom syndrome (synonym: congenital teleangiectatic syndrome) – rare, genetic disorder with autosomal recessive inheritance, which can lead, among other things, to short stature and various malignant (malignant) diseases (eg, leukemia).
    • Cockayne syndrome – genetic disease with autosomal recessive inheritance, which is notable mainly for short stature, premature aging and various malformations.
    • Rothmund-Thomson syndrome – genetic disease with autosomal recessive inheritance, which is notable for erythema (areal redness of the skin) and skin changes similar to stretch marks.
    • Xeroderma pigmentosum (synonyms: Melanosis lenticularis progressiva, also moonshine disease or light shrinkage skin, abbreviated “XP”) – genetic disease with autosomal recessive inheritance, which is notable for various neoplasms of the skin, which are caused by high sensitivity to light (photophobia).
• Gender – men are affected slightly more often than women; mostly occupational.
• Age – older age, with correspondingly high sunlight exposure.
• Skin type – Light skin type (Fitzpatrick I-II).
• Occupations – Occupations with high sun exposure (e.g. in agriculture (field workers), lifeguards, roofers, glass cleaners, garbage collectors, road workers and also ship crews).

Behavioral causes

• Consumption of stimulants
  • Tobacco (smoking)
• Recreational or occupational exposure to UV radiation (UV-A rays (315-380 nm), UV-B rays (280-315 nm); sun; solarium.
• Lack of sun protection

Causes related to disease

• Immunodeficiency (immunodeficiency) – e.g. HIV infection, transplant recipients under immunosuppression.

Medication

• Immunosuppressants (azathioprine; calcineurin inhibitors) → increased risk of actinic keratoses and a transition to squamous cell carcinoma.
• Photosensitizing drugs such as diuretics (draining drugs), antidepressants, painkillers, cardiac drugs, antibiotics, etc.

Environmental pollution – intoxications (poisonings).

• Damage to the skin by UV radiation (UVA, UVB; sun; solarium); recognized occupational disease (occupational disease list, BK list) in the presence of multiple actinic keratoses of the skin by UV radiation.
• Infrared radiation
• X-ray radiation/ionizing radiation
• Anthracene
• Arsenic
• Benzpyrene
• Crude kerosene wax
• Carbon black
• Tar products (lignite tar/lignite workers) and other hydrocarbons.