An actinic keratosis is a rough, scaly patch caused by years of sun. It is a precancer, meaning it is the step before skin cancer rather than cancer itself. Most never progress, but most squamous cell carcinomas start as one, which is why they are treated. A seborrheic keratosis is a common, harmless growth that looks stuck onto the skin, like a piece of wax or a small barnacle. They are not cancer and they do not become cancer. The reason to see a doctor is to be sure that is what you are looking at.
The same eight facts on every condition comparison.
It is ultraviolet damage.
Actinic keratoses are rough, scaly areas caused by UV damage to skin cells.
It appears on sun-exposed skin.
They occur most often on repeatedly exposed areas.
It is precancerous.
Some can progress to squamous cell carcinoma.
Some lesions need a biopsy.
Thick, painful, ulcerated or enlarging spots are checked for invasive cancer.
It is a benign growth.
Surface skin cells form a waxy, warty or stuck-on growth.
Color varies.
It can be tan, brown, gray or almost black.
It is not a precancer.
These growths become more common with age.
Uncertain lesions are tested.
Tissue is examined before any destructive treatment if the appearance is unclear.
Classic actinic keratosis Rough pink or red scaly spot.
Hypertrophic actinic keratosis Thick, raised and crusted.
Actinic cheilitis Rough, dry patches on the lower lip.
Pigmented actinic keratosis Brown and flat.
Classic seborrheic keratosis Raised, waxy, stuck-on growth.
Stucco keratosis Small white-gray bumps on the legs.
Dermatosis papulosa nigra Small dark bumps on the face.
Repeated ultraviolet exposure damages the DNA of surface skin cells, allowing abnormal cells to grow within the epidermis. A rough, scaly patch develops, and some lesions can progress to skin cancer.
A benign overgrowth of surface skin cells creates a localized plaque. Keratin and sometimes pigment collect in the growth, giving it a waxy, rough or stuck-on appearance.
Actinic Keratosis. Usually develops in adults after years of ultraviolet exposure, especially with fair or immunosuppressed skin.
Seborrheic Keratosis. Usually appears in adult life and becomes increasingly common with age.
Actinic keratoses are caused by years of ultraviolet light damaging skin cells. They are a warning sign of sun damage.
Seborrheic keratoses are harmless growths of skin cells that become more common with age.
Fair skin that burns easily is inherited and is the biggest risk.
They often run in families.
Evidence labels come from each condition’s own treatment list.
An over-the-counter form of vitamin B3, taken as a tablet, which modestly reduced new actinic keratoses and new skin cancers in people at high risk. The effect is real but small, and it stops when the tablets stop. It is an add-on to sun protection and treatment, not a replacement for either. Check with your doctor before starting it.
The lower lip is the site almost nobody protects and one of the higher-risk places for a patch to progress. A balm with SPF 30 or higher, reapplied through the day, is the practical way to cover it. It will not treat a lip that is already persistently dry, scaly or cracked — that needs looking at.
A strong urea cream can soften and flatten the rough white growths that scatter over the lower legs, called stucco keratoses, if the roughness is what bothers you. It smooths the surface rather than removing the growth, and it has to be used continuously. It does nothing for thick, dark, stuck-on growths elsewhere.
Wart treatments are often tried on these because the surface looks similar. Salicylic acid can thin the rough top layer, but it does not clear the growth, and it irritates the normal skin around it. The bigger problem is that it is usually being used on something nobody has examined.
This is aftercare, not treatment. A thin layer of plain petroleum jelly over a treated spot keeps the scab soft and gives the neatest healing, under a small dressing rather than an adhesive strip. It does nothing to a growth that is still there.
Daily mineral sunscreen over a spot that has just been treated stops the temporary mark from darkening and helps it fade faster, which matters most on the face, chest and hands. It will not remove a growth or stop new ones forming. Sun is only one of several things that drive these, and age and family history matter more.
Fluorouracil cream (5-FU). The best-studied cream for treating a whole sun-damaged area rather than single spots, usually applied for two to four weeks. It attacks abnormal cells wherever they are, so it also clears patches that had not surfaced yet. The area becomes red, crusted and sore where those cells were, often revealing more than you knew you had — that reaction is the treatment working, and stopping early leaves the area half treated. If you are pregnant or breastfeeding, ask the doctor managing your pregnancy first.
Imiquimod cream. Prompts your own immune system to clear the abnormal cells, applied a few times a week over a longer course than fluorouracil. It also treats the whole field, and it can suit the face and scalp well. Expect redness and crusting, and sometimes a few days of feeling fluey. The same pregnancy advice applies: ask the doctor managing your pregnancy first.
Tirbanibulin ointment. A newer ointment used once a day for five days on the face or scalp. The short course and the milder reaction are the point of it — most people are through the redness and flaking within a couple of weeks. It is used on a limited area at a time, and long-term results are less well known than for fluorouracil.
An anti-inflammatory gel applied twice a day for two to three months. It is much gentler than fluorouracil, which makes it an option for people who cannot manage a strong reaction on visible skin. It clears fewer patches, and the course is long.
A prescription retinoid people often ask about here, because it is known for sun-damaged skin. It smooths texture and helps the mottled color, but trials have not shown that it clears actinic keratoses or prevents skin cancer. It is reasonable for the look of sun damage, and it is not a treatment for the patches themselves.
A high-strength peroxide solution applied in clinic was approved for raised growths on the face and body. It cleared some growths, often needed repeat visits, and commonly caused stinging, crusting and pigment change. It was withdrawn from sale in the United States, so in practice removal is done by hand rather than with a liquid.
An oral retinoid used mainly for organ transplant recipients and others whose immune systems are suppressed, who make large numbers of these patches and progress from them more often. It reduces how many new patches and skin cancers appear while it is taken, and the benefit fades once it is stopped. It has real side effects and needs blood tests. It must never be taken in pregnancy, and pregnancy has to be avoided for three years afterwards.
Freezing with liquid nitrogen is the quickest option for a handful of separate patches, done in a few seconds each with no prescription. It stings sharply, then blisters or crusts and heals over one to three weeks. Its limit is that it only treats what can be seen, so new patches keep arriving from the damaged skin around them. It often leaves a permanently pale mark, which is more noticeable on deeper skin tones — worth asking about before you start.
A light-activated liquid is put on the whole area, left to soak in, then activated with a lamp. It treats a broad field in one or two clinic visits instead of weeks of cream, which suits people who cannot manage a long course at home. The area stings during treatment and is red, swollen and sore for several days, and the treated skin has to be kept out of light straight afterwards.
The thicker, harder patches that freezing struggles with are scraped away under local anesthetic and the base sealed. It is useful when a patch has built up into a lump or a horn, and the scraped material can be sent for testing. It leaves a small scar, and like freezing it treats only the spot in front of you.
A medium-depth peel takes off the damaged top layer across a whole face or scalp at once, so it treats the field rather than single spots. It is an option when creams have not been tolerated. The skin is red and peeling for about a week, and results depend a lot on who is doing it and at what strength.
Not a treatment, but the right answer for a patch that is thick, firm, tender, bleeding, growing quickly, bigger than about a centimeter, forming a horn, sitting on the lip or ear, or unchanged after proper treatment. A few minutes under local anesthetic tells you whether the abnormal cells are still confined to the top layer or have gone deeper. Freezing a patch like that instead removes the evidence without answering the question.
A few seconds of liquid nitrogen makes flatter growths blister and lift off over a week or two, and it is the quickest way to treat several at once. It destroys the growth, so nothing can be examined afterward, which is why it is not used on anything with a question attached. It is used cautiously on the face and on deeper skin tones, because the pigment cells are sensitive to cold and it can leave a pale spot.
The growth is scraped off with a small curette and the base sealed with a fine electric tip. It is controlled and shallow, which is why it is often preferred for small facial growths and for the dark facial growths common on deeper skin tones. Scraping first still gives tissue that can be examined if there is doubt.
When a growth is changing, bleeding on its own, or simply looks unlike your others, part or all of it is taken after numbing and examined under a microscope. It is the only way to be certain, and the threshold for doing it is deliberately low, because the cost of a small biopsy is trivial next to missing a melanoma. An irritated growth is one of the commonest reasons a benign growth ends up being sampled.
The growth is numbed and shaved off level with the skin in a few seconds. It is the method of choice when there is any question about what a growth is, because it produces tissue that can be sent to the laboratory. It leaves a flat mark that fades over months, and it does not stop new growths appearing elsewhere.
An ablative laser can vaporise a growth precisely and is sometimes used when several need treating on the face. Like freezing, it destroys the tissue, so it is only for growths already confirmed as harmless. It is the most expensive of the options and it is not better than a curette for a single growth.
Actinic keratoses are not steady. Individual spots come and go, which is one reason they get dismissed. The trend over years is upward.
Seborrheic keratoses appear slowly, change slowly, then stay. Two departures deserve attention: one growth that starts changing - growing, darkening, bleeding on its own, or itching persistently - and a sudden crop of many new ones over weeks to months.
Squamous Cell Carcinoma
The skin cancer that these patches can turn into. Any one patch is unlikely to progress in any one year, but most squamous cell carcinomas begin in an actinic keratosis or in the damaged skin around one, and people usually have many patches over many years. Treating patches lowers how many of these appear later. A patch that thickens, hurts, itches, bleeds or grows quickly is sampled rather than frozen.
Actinic cheilitis on the lip
The same sun damage on the lower lip, where it shows up as persistent dryness, scaling, cracking or a lip border that has blurred into the skin. It is easy to read as chapped lips, and lip balm does not fix it. The lip matters more than its appearance suggests, because it is a higher-risk site if a patch progresses, so a dry scaly lower lip that has not settled in a month should be looked at.
Catching on clothing makes it flare
A growth caught by clothing, a strap or a waistband can turn red, swollen, itchy, crusted or sore, and can bleed. That is an irritated seborrheic keratosis. It settles, but it looks alarming and often prompts removal or a sample.
Arrange assessment of persistent rough spots. Rapid growth, tenderness, thickening, ulceration or bleeding raises concern for skin cancer.
Have a new, changing, bleeding or uncertain growth assessed; skin cancer can sometimes resemble a harmless stuck-on growth.
No. It is a precancer - abnormal cells in the top layer of skin that have not formed a tumor. A minority become squamous cell carcinoma, and they are treated because most squamous cell carcinomas begin this way.
Low, for any single patch in any single year. Published estimates vary too widely to quote. What matters is cumulative: more patches, for longer, with more sun. A suppressed immune system raises it considerably.
It stings for a few seconds and aches afterward. It blisters or crusts within a day or two and heals over one to three weeks. A pale mark often remains where the skin regrows with less pigment - sometimes permanent, and more noticeable on deeper skin tones.
That is how it works. Fluorouracil and imiquimod provoke a reaction exactly where abnormal cells are, so the area turns red, crusted and sore, often revealing more patches than you knew you had. It settles a couple of weeks after finishing. Stopping early leaves the area partly treated.
New ones almost certainly will, because the sun damage remains. That is not treatment failure. Most people settle into periodic checks, occasional retreatment and daily sun protection - the protection is what reduces how many new ones appear.
A few discrete patches, and freezing is efficient. Many patches, or a whole area of damaged skin, and a cream or photodynamic therapy lasts longer, because it reaches cells that have not surfaced yet. Downtime is part of the choice.
It could be, which is why it should be looked at rather than diagnosed at home. Melanoma is sometimes mistaken for a seborrheic keratosis, and a dermatoscope resolves most of these in seconds. The concerning features are change in size, shape or color, bleeding without being knocked, an irregular edge, and a growth unlike your others. Book rather than watch.
Age and family history account for nearly all of it. They accumulate steadily from the forties onward, and someone whose parents had many will develop many. A genuinely sudden crop over weeks to months, especially with itching, is different and worth examining.
No. Removal deals with that growth, not the age and inherited tendency behind it, so new ones can keep appearing elsewhere. That is expected, not a failed removal.
Often, at least for a while. A flat spot darker or paler than nearby skin is common, and dark marks usually fade over months. Pale marks can be permanent and are more noticeable on deeper skin tones, so ask about the method and do a test spot before treating a large area. Daily sunscreen on the treated spot makes a real difference.
Most likely it caught on clothing, a strap or a razor and became an irritated seborrheic keratosis. They look far worse than they are and they settle. Still have it looked at - an irritated growth is one of the harder ones to be sure about by appearance, and a growth that bled with nothing catching it is a different question.
As many as you and your doctor think sensible, usually in sessions rather than all at once. It is normally considered cosmetic, so ask about cost first. On the face, and particularly on deeper skin tones, start with a small test area and see how it heals.
Sources
