An actinic keratosis is a rough, scaly patch on skin that has received ultraviolet radiation over many years. The cells of the outer layer have been altered by that exposure and no longer mature normally. Health bodies describe a small chance that such a patch can develop into a skin cancer, which is why they are assessed rather than ignored.
What is actually happening in the skin?
Ultraviolet radiation reaches the cells of the epidermis and damages the genetic material inside them. Most of that damage is repaired, and cells beyond repair are usually removed. Neither process is perfect, and small failures accumulate silently across decades.
An actinic keratosis is where enough has accumulated in one place to change how cells behave. They no longer mature and shed in the orderly way their neighbours do, and the surface above them becomes rough, dry and scaly. The patch is thin, often better felt than seen, and it sits within the epidermis rather than below it.
Distribution records exposure rather than habit. The face, the ears, a scalp where hair has thinned, the backs of the hands and the forearms are the classic sites, because those surfaces have faced the sky for a lifetime. Somebody who worked outdoors carries a different map from somebody who did not.
What happens next is where careful wording matters. Health bodies describe a small chance that such a patch can develop into a skin cancer, and most do not. That statement supports assessment and monitoring, and it supports neither alarm nor dismissal.
How would a dermatologist describe it?
Actinic and solar are used interchangeably, both meaning caused by sunlight. Keratosis describes a thickening of the outer layer, and it appears in the names of several unrelated conditions.
Field change describes an area where skin around an actinic patch has received the same exposure as the visible patch, even where it looks normal. Naming it explains why a clinician examines and sometimes treats an area rather than a spot.
Hyperkeratotic describes an actinic patch with pronounced surface thickening. Cutaneous horn describes a firm projection that occasionally develops from one, and it is examined carefully because appearance alone does not settle what lies beneath it.
The published criteria describing which features should prompt further assessment are maintained by the bodies that issue them. They are precisely worded, they are revised, and they are linked below rather than paraphrased here. Rewriting a checklist is a reliable way of changing its meaning while appearing to preserve it, and on this subject that risk is not worth taking.
What usually happens at a consultation?
The history covers sun exposure across a lifetime: outdoor work, time abroad, sunburn, sunbed use, and any previous skin cancers or removals. Questions about medicines affecting your immune system are routine, because they bear on the assessment.
Examining for actinic damage generally covers the whole of the sun-exposed skin rather than the patch you came about, and a clinician will run a hand across the surface as well as look at it. Texture reveals actinic damage that the eye misses.
A dermatoscope is used, and where anything is uncertain a sample may be arranged. What a biopsy involves practically is described elsewhere on this site, and being offered one is a step towards an answer rather than a conclusion already reached.
Discussion of what to do next depends on how many patches there are and how large an area is involved. Treating a single patch and treating a field are different conversations, and both belong in the room.
What is worth asking?
Ask whether the clinician is treating one actinic patch or an area, and why. That single answer explains most of what follows and is rarely offered unprompted.
Ask what should bring you back rather than wait for a routine appointment. Named changes are far easier to watch for than a general instruction to keep an eye on things.
Ask what the examination found beyond the patch you raised. Actinic change is frequently more extensive than the part somebody has noticed, and knowing the extent tells you what the follow-up is for.
If you spent years working outdoors, say so early. That history changes the assessment more than almost anything else you can offer.
What this page does not do
Nothing here tells you whether a rough patch on your skin is an actinic keratosis, and nothing here helps you decide whether anything is or is not a skin cancer. That judgement requires examination by somebody qualified to make it. No treatment is recommended, no criteria are reproduced, and no threshold, factor or interval appears anywhere on this page.
Common questions
Are actinic keratoses skin cancer?
They are not, and the distinction matters. Health bodies describe them as patches of sun-damaged skin carrying a small chance of developing into skin cancer, which is a different statement. That is precisely why they are assessed and followed rather than either ignored or treated as an emergency.
Why do they appear where they do?
They follow cumulative exposure rather than any single episode. The face, ears, scalp where hair has thinned, the backs of the hands and the forearms are the usual sites because those are the surfaces that have faced the sky for decades.
Why can I feel one before I can see it?
Texture often precedes appearance, and a clinician running a hand over the skin is using that. A patch that feels rough where the surrounding skin is smooth is frequently found this way, which is one reason the examination involves touch.
Does having one mean more will follow?
Skin that has produced one patch has generally received the exposure that produces others, which is why clinicians examine the whole area rather than the patch you point at. What follows from that in your case is a matter for the person examining you.
Does sun protection still matter once they have appeared?
Exposure accumulates across a lifetime and continues to accumulate, so what happens from now on is still relevant. What is appropriate for you specifically belongs with the clinician; this site publishes no thresholds, factors or timings of its own.
Sources
- Actinic keratoses (solar keratoses) — NHS (United Kingdom) · accessed
- Patient information on skin conditions — British Association of Dermatologists (United Kingdom) · accessed
Last updated . How this page was written.