Actinic Keratosis

Actinic keratosis on balding head[1]

Actinic keratosis is a UV light–induced lesion of the skin, which is considered as potentially pre-cancerous. The lesion may appear on any sun-exposed area.

Actinic Keratosis is related to the following process: Radiation.

Presentation

Actinic keratosis has been known to show signs of Bowen disease or carcinoma in situ. The patients present with the following clinical features [2].

  • Areas of skin that are usually exposed, like head, face, neck, forearms and hands etc. show minuscule lesions.
  • The lesions are small, have indurated margins, 1 cm in diameter, tan brown or red in color and grow close together in patches.
  • The lesions appear as elevated skin areas, resembling warts, and may even bleed.
  • The skin becomes rough, with a sand-paper like texture.
  • The lesions gradually enlarge and become scaly.
  • The skin is itchy and tender.
  • In immunocompromised patients, the lesions become erythematous, due to flare formation.
  • • The lesions persist over years. They may either regress with care or get transformed into malignant lesions on further exposure to ultraviolet (UV) light.

Workup

Not much investigation is needed to diagnose a patient suffering from actinic keratosis. Thorough skin examination is usually enough to recognize actinic keratosis clinically. In some patients, skin biopsy is useful in ruling out the suspicion of malignancy.

Treatment

Conservative treatment can be done with the following:

  • Topical chemotherapeutic agents like 5-fluorouracil gel [3] [4]
  • Anti-inflammatory drugs
  • Imiquimod [5]

The surgical techniques that can be employed include the following:

  • Cryosurgery (most effective)
  • Chemical peeling
  • Laser surgery [6]
  • Laser resurfacing [7]
  • Photodynamic therapy (PDT) in which the skin is exposed to blue light [8]
  • Curettage and excision
  • Electrosurgery and cauterization

Combination therapy with 5-FU followed by cryotherapy with liquid nitrogen is an effective mode of treatment.

Prognosis

In about 10% of the people, actinic keratosis progresses to squamous cell carcinoma. Early treatment prevents the development of carcinoma [1]. Although metastasis is rare, the lesions have a high tendency for malignancy. 2 to 10% of the malignant cases can invade the internal organs, proving to be life threatening. The earlier the diagnosis; more are the chances of cure.

Etiology

Excessive exposure to UV radiation, even from indoor sources like lamps etc. can trigger the development of these lesions. Excessive exposure to X-rays or industrial chemicals can also be the reason. A large number of cases of actinic keratosis have been related with the mutations in TP53 gene, the tumor suppressor gene.

Actinic keratosis has been further classified into:

  • Hyperkeratotic actinic keratosis (associated with high risk of malignancy)
  • Pigmented actinic keratosis (lesions with rough, scaly surface)
  • Lichenoid actinic keratosis (soft, shiny lesions, occurring in areas prone to friction)
  • Atrophic actinic keratosis

Epidemiology

The highest prevalence is in countries like South Africa and Australia where sunlight exposure and fair skinned population are relatively higher. In the northern hemisphere, it is found in 11 to 25% of the people at the age of 40 and above.

Fair skinned people are mostly commonly affected by the sunlight. Freckled individuals are at a higher risk too. Population living in areas with long-term sunlight exposure like Australia is, therefore, at higher risk of developing the disease as compared to those with low exposure to sunlight.

Older population is implicated with a high risk of actinic keratosis as damage caused by sunlight builds up over the years, hence called senile keratosis. Men are affected more than women owing to the fact that they spend relatively more time outdoors as compared to women. Caucasians are most susceptible as compared to Hispanics and Asians with darker skins.

Individuals with immunosuppression, like those undergoing cancer chemotherapy or organ transplantation, or those with immunocompromised states like diabetes or HIV are at a relatively higher risk for developing the disease. Individuals with skin disorders like xerdoderma pigmentosum and albinism are prone to develop actinic keratosis too.

Sex distribution
Age distribution

Pathophysiology

The mutations in the suppressor gene cause disinhibition of tumor suppression, thereby inducing tumorigenesis. The basal cell layer of the skin is the first to get affected; it shows hyperplasia of basal cells. Pleomorphic keratinocytes start accumulating in the stratum basalis. Uninhibited growth ensues, sometimes extending into the superficial as well as the deeper layers of skin. The cellular architecture is lost as a result of rapid proliferation of cell. The nuclear-cytoplasmic ratio is high and mitotic figures are seen; a sign of malignancy.

A dense infiltration of inflammatory cells occurs. Hyperkeratosis, with occasional areas of parakeratosis is seen. Granular layer is lost. As the disease progresses, it can invade the surrounding areas, giving rise to squamous cell carcinoma. Therefore, actinic keratosis is considered a precancerous state.

Prevention

The following measures are effective in preventing the development of actinic keratosis.

  • Sunlight should be avoided as much as possible by standing indoors [9] [10].
  • Broad spectrum sunscreens should be used for protection from harmful radiations in the sunlight.
  • When going out, full clothing should be worn that covers the arms and the legs.
  • Basking in the sun has to be avoided.
  • The use of tanning beds or indoor tanning devices should also be avoided.
  • Frequent head to toe self-examination should be done to look for any sort of skin changes.

Summary

Actinic keratosis, also known solar keratosis or senile keratosis due to its association with old age, is one of the most common pre-malignant lesions of skin. The condition is associated with chronic exposure to sunlight. The ultraviolet radiations in sunlight induce these scaly growths and if left untreated, they can progress into squamous cell carcinoma, although there have been reports of regression or stability of these lesions.

Patient Information

Actinic keratosis is a skin disorder that can turn into skin cancer, if not immediately tended to. The main reason is long term exposure to sunlight. Fair skinned people who spend long hours in the sun are especially at risk.

It shows up as small red skin eruptions. The skin becomes itchy and painful. The eruptions on the skin may harden and can also bleed. Avoiding sunlight as much as possible and using sunscreen lotions is the best possible preventive measure.

Self-assessment

References

  1. Bogal CB. Actinic keratosis: treat lesions to reduce cancer risk. Advance for nurse practitioners. Jan 2010;18(1):18.
  2. Werner RN, Sammain A, Erdmann R, Hartmann V, Stockfleth E, Nast A. The natural history of actinic keratosis: a systematic review. The British journal of dermatology. Sep 2013;169(3):502-518.
  3. Gupta AK, Davey V, McPhail H. Evaluation of the effectiveness of imiquimod and 5-fluorouracil for the treatment of actinic keratosis: Critical review and meta-analysis of efficacy studies. Journal of cutaneous medicine and surgery. Oct 2005;9(5):209-214.
  4. Gupta AK, Paquet M. Network meta-analysis of the outcome 'participant complete clearance' in nonimmunosuppressed participants of eight interventions for actinic keratosis: a follow-up on a Cochrane review. The British journal of dermatology. Aug 2013;169(2):250-259.
  5. Hadley G, Derry S, Moore RA. Imiquimod for actinic keratosis: systematic review and meta-analysis. The Journal of investigative dermatology. Jun 2006;126(6):1251-1255.
  6. Jang YH, Lee DJ, Shin J, Kang HY, Lee ES, Kim YC. Photodynamic therapy with ablative carbon dioxide fractional laser in treatment of actinic keratosis. Annals of dermatology. Nov 2013;25(4):417-422.
  7. Sherry SD, Miles BA, Finn RA. Long-term efficacy of carbon dioxide laser resurfacing for facial actinic keratosis. Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons. Jun 2007;65(6):1135-1139.
  8. Ericson MB, Wennberg AM, Larko O. Review of photodynamic therapy in actinic keratosis and basal cell carcinoma. Therapeutics and clinical risk management. Feb 2008;4(1):1-9.
  9. Cohn BA. From sunlight to actinic keratosis to squamous cell carcinoma. Journal of the American Academy of Dermatology. Jan 2000;42(1 Pt 1):143-144.
  10. Feller L, Khammissa RA, Wood NH, Jadwat Y, Meyerov R, Lemmer J. Sunlight (actinic) keratosis: an update. Journal of preventive medicine and hygiene. Dec 2009;50(4):217-220.

  • Actinic cheilitis: a review of 152 cases - GE Kaugars, T Pillion, JA Svirsky, DG Page - Oral Surgery, Oral , 1999 - Elsevier
  • Comparison of the efficacy and safety of Jessner's solution and 35% trichloroacetic acid vs 5% fluorouracil in the treatment of widespread facial actinic keratoses - N Lawrence, SE Cox, CJ Cockerell - Archives of , 1995 - Am Med Assoc
  • , right–left comparison of topical methyl aminolaevulinate‐photodynamic therapy and cryotherapy in subjects with actinic keratoses: a multicentre, randomized - C Morton, S Campbell, G Gupta - British Journal of , 2006 - Wiley Online Library
  • A randomized multicenter study to compare two treatment regimens of topical methyl aminolevulinate (Metvix®)-PDT in actinic keratosis of the face and scalp - M Tarstedt, I Rosdahl, B Berne - ACTA , 2005 - medicaljournals.se


Media References

  1. Actinic keratosis on balding head, CC BY-SA 4.0
Self-assessment