actinic keratosis

What is actinic keratosis?

Actinic keratosis, also known as solar keratosis, are an early form of squamous cell carcinoma that appear on continuously sun-exposed skin. 1

They manifest as skin color or slightly reddish spots  that can  be rough to the touch. Sometimes they can also be really thick, simulating a little horn. 

They can present as single lesions or multiple lesions. In the latter, the possibility of a field of cancerization (ie. area of sun-damaged skin that can be found surrounding each AK lesion and that displays the same genetic changes found in the lesion itself) must be taken into account

Actinic keratosis is one of the most common diseases in the worldwide population. Its incidence has a clear tendency to grow due to ageing of the population, changes in lifestyle, with a large increase in outdoor activities, and a high prevalence in the immunosuppressed population derived from the rise in the transplantation of solid organs and the more frequent use of immunosuppressive treatments for chronic inflammatory diseases. 2
 
However, it is still an underdiagnosed disease. Many patients with actinic keratosis  have never consulted the doctor. Some of the reasons might be that these lesions are almost always asymptomatic (ie. do not produce itching, pain or any other symptom); they mostly affect older people where cosmetic aspects already occupy a secondary place; and finally, there is  a lack of knowledge in the general population about the implications of presenting actinic keratosis. 2
 

What are the risk factors for developing actinic keratosis?

  • The biggest risk factor for the development of actinic keratosis is a long exposure to UV light (sun –exposure or bed tanning). In this sense, people of advanced age that have worked outdoor for a long time, people that like playing outdoor sports, going to the beach or people living in countries closer to the equator, are at higher risk of developing actinic keratosis.3-5
  • Other risk factors are male sex and people with fair skin color with red or blond hair.3-5
  • Finally, immunosuppressed people are also at a higher risk of developing actinic keratosis.6-8
 

Why is it important to diagnose actinic keratosis?

There are two main reasons why we should never ignore these lesions, even though they may be completely asymptomatic.
 
  • There is a risk of those lesions to evolve to invasive skin cancer (squamous cell carcinoma). Although the individual risk of each lesion is low, we are not capable of identifying which lesion is the one that may evolve in the future.9
  • The presence of actinic keratosis is a sign of sun-damage in the skin, which helps identify people with a higher risk of developing any type of skin cancer.10

Where do we look for actinic keratosis?

Actinic keratosis usually appears on areas of chronic sun-exposed skin2:

  • Scalp of a bald person
  • Face (including nose, ears, forehead, cheeks, lower lip…)
  • Neckline
  • Dorsum of hands and forearms
  • Legs

 

It is important to examine yourself at home periodically in front of a mirror.

If you have a suspicion that you may have some of these lesions, it is important to request for an appointment with your general practitioner to evaluate your risk and start treatment or to derivate to a dermatologist.

 

How can we prevent the appearance of actinic keratosis?

The first step towards preventing actinic keratosis is by preventing from UV-light:11-14
  • Using the right sun screen whenever you go out in the sun. Your sun screen should protect against UVA- and UVB radiation. The sun protection factor (SPF) indicates by which factor the skin's innate protective ability is multiplied. In other words, it tells you how long your skin can be exposed to the sun without getting a sunburn, it should be at least SPF 30. It is generally recommended to apply them 20-30 minutes before sun exposure. 
  • It is also important to use a cap or a hat, especially in bald people.
  • Consider wearing sun protective textiles.
  • Avoid sun exposure between 11am and 3pm.
  • Avoid artificial sunlight (sun beds/tanning salons).
  • Schedule an annual dermatologic skin exam.
 

How to treat actinic keratosis

It is important to treat actinic keratosis, in order to prevent its progression into an invasive skin cancer.1

Currently, there is a wide range of possibilities to treat actinic keratosis. The choice of treatment will be based on the assessment made by your dermatologist in conjunction with the opinion of the patient.1

Broadly speaking, treatments can be divided into 2 groups:

 

Treatments applied in consultation:

These treatments (cryotherapy, surgery, curettage, laser or conventional photodynamic therapy) are performed by the doctor and are usually indicated for isolated lesions (except for photodynamic therapy that is also indicated for treating the field of cancerization).

 

Treatments applied at home:

These treatments are performed by the patient applying a topical product in the affected area at home during a period between 1 day to several months, depending on the choice of treatment. They are specially indicated when the patient has several actinic keratosis, and are mandatory in the presence of field of cancerization.

In many occasions, combinations with different options may be used to achieve better results.

References:

  1. Werner RN, et al. International League of Dermatological Societies (ILDS) Evidence and consensus based (S3) Guidelines for the Treatment of Actinic Keratosis, European Dermatology Forum, 2015. Accessed online on July 14th, 2015 at http://www.euroderm.org/edf/index.php/edf-guidelines/category/5-guidelines-miscellaneous.
  2. Ferrándiz C, et al.  Prevalence of actinic keratosis among dermatology outpatients in Spain. Actas Dermosifiliogr. 2016.
  3. Harvey I, Frankel S, Marks R, Shalom D, Nolan-Farrell M. Nonmelanoma skin cancer and solar keratoses. I. Methods and descriptive results of the South Wales Skin Cancer Study. Br J Cancer 1996; 74: 1302–1307.
  4. Frost CA, Green AC. Epidemiology of solar keratoses. Br J Dermatol 1994; 131: 455–464.
  5. Frost CA, Green AC, Williams GM. The prevalence and determinants of solar keratoses at a subtropical latitude (Queensland, Australia). Br J Dermatol 1998; 139: 1033–1039.
  6. Parrish JA. Immunosuppression, skin cancer, and ultraviolet A radiation. N Engl J Med 2005; 353: 2712–2713.
  7. Stockfleth E, Ulrich C, Meyer T, Christophers E. Epithelial malignancies in organ transplant patients: clinical presentation and new methods of treatment. Recent Results Cancer Res 2002; 160: 251–258.
  8. Tessari G, Girolomoni G. Nonmelanoma skin cancer in solid organ transplant recipients: update on epidemiology, risk factors, and management. Dermatol Surg 2012; 38: 1622–1630.
  9. Werner RN, Sammain A, Erdmann R, Hartmann V, Stockfleth E, Nast A. The natural history of actinic keratosis: a systematic review. Br J Dermatol 2013; 169: 502–518.
  10. Chen GJ, Feldman SR, Williford PM, Hester EJ, Kiang SH, Gill I, et al. Clinical diagnosis of actinic keratosis identifies an elderly population at high risk of developing skin cancer. Dermatol Surg. 2005;31:43-47.
  11. Ulrich C, Jurgensen JS, Degen A, Hackethal M, Ulrich M, Patel MJ, et al. Prevention of non-melanoma skin cancer in organ transplant patients by regular use of a sunscreen: A 24 months, prospective, case-control study. Br J Dermatol. 2009;161 Suppl 3:78-84.
  12. Berardesca E, Bertona M, Altabas K, Altabas V, Emanuele E. Reduced ultraviolet-induced DNA damage and apoptosis in human skin with topical application of a photolyase-containing DNA repair enzyme cream: Clues to skin cancer prevention. Mol Med Report. 2012;5:570-574.
  13. Thompson SC, Jolley D, Marks R. Reduction of solar keratoses by regular sunscreen use. N Engl J Med. 1993;329:1147-1151.
  14. Darlington S, Williams G, Neale R, Frost C, Green A. A randomized controlled trial to assess sunscreen application and beta carotene supplementation in the prevention of solar keratoses.A rch Dermatol. 2003;139:451-455.
  15. Stockfleth E., the paradigm shift in treating actinic keratosis: a comprehensive strategy. J Drugs Dermatol 2012;11:1462-1467.