Solar keratoses (also known as actinic keratoses or sun-spots) are rough, reddened, scaly, flaky or crusty patches on the skin that are caused by excessive exposure to Ultraviolet Radiation (UV rays), usually over a long period of time.
They are seen in all skin types, even people with “strong” or olive skin.
They are now considered to be pre-cancerous changes – that is, eventually a proportion of them turn into Squamous Cell Carcinoma. This is a cancer that can spread through the body, and does sometimes kill people.
The exact number of sunspots that will turn into cancer is not known - it is thought to be about 10%, although experts differ in their estimates, from 0.01% to 100%!
It is not possible to look at a group of sunspots and predict which ones will become cancer, and when.
Sometimes a sunspot will give clues, such as growing rapidly, becoming red, scabby/bleeding, thickened or tender especially when squeezed. Such a spot should be partly or completely removed to be checked under the microscope by a pathologist, and then treated appropriately if it is a cancer.
Sometimes however, a red scaly patch that looks like “just a sunspot” can actually be something far worse.
This is why it is so important to follow up on any “sunspot” that is behaving differently – for example, not responding
Treatment:
Actinic keratoses can be treated many ways: freezing, creams, PDT and excision can be used. Or some can be monitored rather than removed.
We look at patients with actinic keratoses in three different circumstances:
Person with one or two actinic keratoses
Person with 10 or 20 actinic keratoses
Person with so many that one almost merges with others surrounding it
In the first situation it is very common to treat the odd actinic keratosis with cryotherapy.
When there are greater numbers, freezing is still the most common treatment. Sometimes thicker or larger lesions are biopsied or excised to ensure they are not invasive SCCs.
When a large skin area appears to be one actinic keratosis after another, we call this a "field effect". In this situation, creams and PDT are often more prominent in our management choices.
Talk to your doctor about your needs and management of your sunspots.
Dr. Dixon would like to thank Dr. Ceridwen Lloyd for her contribution of this fact sheet.
Dr. Anthony Dixon