Actinic Keratosis

Actinic Keratosis

Actinic keratoses (AK; also termed solar keratoses) are pre-malignant lesions arising from the keratinocytes of the epidermal layer of the skin. AK lesions commonly occur on skin that is regularly exposed to the sun, such as the backs of the hands, forearms, scalp and face. They often remain benign for years but can transform into a carcinoma in situ. Over several years, the lesions gradually progress, with around approximately 5% of them eventually turning into invasive carcinomas.

Once they penetrate into the dermis, they become invasive carcinomas. Rarely these can metastasise, resulting in death.  AKs should therefore be treated soon after diagnosis.

AK Epidemiology and Incidence

Incidence

  • AKs are the most frequently seen pre-malignant lesions in humans.
  • The incidence is highest in Australia, where the light-skinned population is predominant and outdoor activities are popular. 
  • They are very common in the Caucasian population, e.g. 7-19% of Australians aged over 40 years are diagnosed every year. In the US, prevalence rates of between 11-26% have been reported13.
  • Over the age of 70, 34% of males and 18% of females were found to have AKs in the US13.


Risk factors

Risk factors for the development of AKs include:

  • Cumulative sun exposure.
  • There is a predisposed genotype/phenotype. Individuals with fair skin, particularly those with freckles, blue eyes and blonde or red hair are most at risk.
  • AK usually occurs in individuals over 45 years of age, although development of initial AK lesions can be observed in younger patients (as early as in their 20-30's) - noted especially in Australia and the south-western US13.

 

Clinical Features of AK

  • AKs are dry, rough, yellow-brown lesions with well-defined scales that do not flake off. They may become thick and horny, and sometimes bleed.
  • Lesions can exist singly but often occur multiply.
  • Both single and multiple growths are slow-growing.
  • They are small with a diameter of less than 1 cm.
  • Although AKs may occasionally spontaneously resolve, they also have the potential to develop into a malignant neoplasm, with an estimated 0.025->10% of AKs developing into squamous cell carcinoma (SCC) per year11.


Diagnosis of AK

Diagnosis of AK is usually based on clinical features. However the diagnosis of cancer is histological. The most common differential diagnoses of NMSC are benign tumours or other types of skin cancers. More rarely, they may be confused with inflammatory or infectious skin lesions.

Treating AK

Options include:

  • Photodynamic therapy (PDT) - Metvix® - PDT
  • Cryotherapy
  • Surgical approaches:
    • Curettage and electrodesiccation
  • Topical Therapies
    • 5- Fluorouracil
    • 3% Diclofenac gel
    • 5% Imiquimod cream

For a more detailed explanation of these therapies click here (by clicking on this link you will be leaving this site - Galderma is not responsible for the content).

References