Actinic keratosis: Diagnosis
Actinic keratosis is an area of the skin damaged by ultraviolet radiation that appears in zones exposed to the sun for years. Its appearance is variable.
How is actinic keratosis diagnosed?
Actinic keratosis is often diagnosed based on clinical features. Your primary care provider or dermatologist can establish diagnosis based on the following:
- Review of your past medical history. Your doctor will assess whether you are at risk of developing actinic keratosis, for example, by working or playing sports outdoors without adequate sun protection.
- Physical exam. Your doctor will assess your skin condition and any presenting lesions. To do this, your doctor may use a dermatoscope—an optical instrument similar to a magnifying glass with light—to examine the lesions in more detail. This technique, known as dermoscopy, will allow your doctor to observe the lesions below the skin’s surface and obtain a magnified image.
However, sometimes, the doctor may find it difficult to differentiate between lesions when doing an AK diagnosis. In these cases, a biopsy of the lesion will be performed. This procedure involves taking a sample of tissue for a closer examination under a microscope.
Actinic keratosis and squamous cell carcinoma
Differential diagnosis between actinic keratosis and invasive squamous cell carcinoma is key. This type of carcinoma, also called squamous cell carcinoma, is a skin cancer with the ability to invade other tissues. The risk of actinic keratosis becoming an epidermoid carcinoma is low, but it does exist and, since it is an invasive cancer, ensuring early diagnosis and treatment is essential.
Even though there are generally no clear signs evidencing the transformation of a lesion into squamous cell carcinoma (meaning, actinic keratosis and squamous cell carcinoma may look the same), the doctor may have suspicion if the lesion:
- is inflamed or indurated;
- is ulcerated or bleeds;
- is larger than 2 centimeters;
- grows rapidly;
- does not heal after the application of an appropriate treatment or reappears shortly after being treated successfully.
In some people the risk of actinic keratoses progressing into squamous cell carcinoma is higher, including immunosuppressed or vitiligo patients, or those with albinism and psoriasis. In these patients, dermatologists usually order a biopsy of all actinic keratoses. Also, actinic keratoses located in the hands, forearms, legs, around the eyes, eyelids, ears or lips are also usually biopsied. Actinic keratoses in these areas are more likely to progress into invasive squamous cell carcinoma, or the carcinoma is more aggressive when it does appear.
References
- Werner RN, Stockfleth E, Connolly SM, et al. Evidence- and consensus-based (S3) Guidelines for the Treatment of Actinic Keratosis - International League of Dermatological Societies in cooperation with the European Dermatology Forum – Short version [Internet]. J Eur Acad Dermatol Venereol. 2015;29(11):2069-79. Available at: http://doi.wiley.com/10.1111/jdv.13180
- Richard MA, Amici JM, Basset-Seguin N, Claudel JP, Cribier B, Dreno B. Management of actinic keratosis at specific body sites in patients at high risk of carcinoma lesions: expert consensus from the AKTeamTM of expert clinicians [Internet]. J Eur Acad Dermatol Venereol. 2018;32(3):339-346 [cited 2020 Feb 19]. Available at: http://www.ncbi.nlm.nih.gov/pubmed/29235161