What are actinic keratosis?
These are aberrant proliferations of keratinocytes (the cells that make up the epidermis, the outermost layer of the skin) as a result of chronically accumulated ultraviolet radiation – usually due to passive or active sun exposure. These are lesions with the potential to degenerate into squamous cell carcinoma of the skin, which is why they are classified as “pre-malignant“.
What do they look like?
They manifest as papules (palpable lesions) in the form of flaking or crusting with a scratchy touch and adhering to the skin of areas exposed to the sun. The main characteristic is the rough touch. Their coloration is usually whitish or pink, although red, yellowish or even black (pigmented) forms can be observed. It is not uncommon for them to flake, disappear and reappear cyclically. Occasionally they can cause little bleeding.
Why do they appear? Where do they appear?
The main risk factor is chronic passive and/or active sun exposure , which is why they usually appear in areas uncovered and exposed to ultraviolet radiation: the face, the scalp in alopecic people, on the décolleté and the back of the hands. It is possible that they may also occur on the lower lip (actinic chelitis), and in this case it should be known that squamous cell carcinomas of the lip have a greater potential for metastasis, so early treatment is a priority.
Who can have this pathology?
Practically any human being, although they are much more common in people with fair skin and who have lived exposed to the sun. They usually accompany other signs of chronic skin aging, such as solar lentigines, wrinkles, skin atrophy and telangiectasias. They usually occur in people over 50 years of age.
Are they very common? What does it mean to have this pathology?
Actinic keratoses are one of the most frequent reasons for consultation in dermatology. Up to 80% of subjects with fair skin (Fitzpatrick phototypes I – III) have some actinic keratosis after the age of 60.
Because they are a consequence of chronic sun damage, it is common to present several actinic keratoses simultaneously, which reflects the concept of “cancerization field“: all the skin in an area exposed to the sun is affected with alterations in the genetic material, since dysplasia does not occur in isolation on some islands of skin.
The fact of having this pathology means that the genetic material of keratinocytes is damaged by ultraviolet radiation and that you suffer a higher risk of skin cancer. For this reason, it is necessary to carry out regular check-ups with the dermatologist, treating the lesions as soon as they are detected. Your dermatologist will tell you what type of treatment is the most recommended in your case.
Are they skin cancer?
It is a difficult question to answer, since the boundary between dysplasia (cellular alterations prior to neoplasia or cancer) is sometimes very difficult to establish.
Although some authors classify them as carcinomas in situ. This means a type of cancer that only affects the most superficial part of the skin and that does not have the potential to spread to other organs. However, because they sometimes disappear on their own, other authors do not consider them cancers as such but dysplastic lesions with the potential to evolve into a squamous cell carcinoma.
In conclusion, they must be interpreted as dyspasic skin lesions (with the potential to develop cancer) that must be treated resolutely to prevent this risk from being consummated.
What is the risk of degeneration to skin cancer of this pathology?
It is believed that, if left untreated, the cumulative risk of invasive squamous cell carcinoma is 5 – 20%. However, the scientific community believes that squamous cell carcinomas derived from actinic keratoses tend to have a better degree of differentiation and that the rate of metastasis in them is lower than in squamous cell carcinomas originating from healthy skin (de novo).
Calculations show that the average time of degeneration from actinic keratosis to squamous cell carcinoma is about two years, so it is important to have quarterly or semi-annual check-ups with your dermatologist if you have suffered from actinic keratosis.
What are the risk factors for suffering from this pathology?
The main one is the solar radiation accumulated chronically with active and/or passive exposure to sunlight. Other risk factors are light skin phototypes, age, the patient’s immune status and exposure to other types of radiation.
How are they diagnosed?
In general, the dermatologist is able to diagnose them by observation and palpation, although it is advisable to perform an examination with dermoscopy of the lesions. If there is diagnostic doubt, a skin biopsy can be performed, although it is rarely necessary.
What should I do if I have been diagnosed with actinic keratosis?
You should use a sunscreen with SPF 50 regularly, not only when you are going to sunbathe actively. The use of sunscreen has been shown to promote the disappearance of some actinic keratoses spontaneously.
You can find more tips on photoprotection here.
How are they treated?
Although some lesions disappear spontaneously, it is advisable to treat any actinic keratosis, as it is impossible to predict which ones will disappear and it is known for sure that any of them can lead to skin cancer. Check the treatment block for this pathology here.
ACKNOWLEDGEMENTS
To Dr. Leo Barco for his clinical images. Visit his online Atlas of Dermatology.
REFERENCES
Schmitt JV, Miot HA. Actinic keratosis: a clinical and epidemiological revision. An Bras Dermatol. 2012 May-Jun; 87(3):425-34.
