Seborrheic keratosis

A seborrheic keratosis is a noncancerous skin growth. It develops from cells in the outer layer of the skin. These growths are common in adults and become more likely with age.

The name may sound similar to actinic keratosis, but the two are different. An actinic keratosis is a sun-damaged area that can sometimes become skin cancer. A seborrheic keratosis is benign, meaning it is not cancerous or precancerous.

Seborrheic keratoses often look as if they have been pasted or “stuck” onto the skin. They may be flat at first and become thicker over time. Their color can range from skin-colored or yellowish to brown or almost black.

Older names include “senile wart” and keratosis seborrheic. However, seborrheic keratoses are not warts and are not caused by the viruses that cause warts. They are not contagious.

Most do not require treatment. The main reason to have one assessed is to make sure that it is not another type of growth, especially skin cancer. Removal may be considered if it catches on clothing, becomes irritated, or bothers you because of its appearance.

A seborrheic keratosis usually appears as a clearly defined spot or bump. You may have one growth or many.

Typical features include:

• A waxy, scaly, rough, or wart-like surface
• A round or oval shape with a distinct edge
• A “stuck-on” appearance
• Color ranging from pale tan to dark brown or black
• Size ranging from a tiny spot to several centimetres across
• Mild itching or irritation, especially where clothing rubs

Common locations include the chest, back, shoulders, scalp, face, abdomen, and skin folds. They can occur almost anywhere except the palms of the hands and soles of the feet.

Some are thin and only slightly raised. Others become thick, crumbly, or ridged. Small white or dark plugs may be visible within the surface.

On darker skin, multiple small dark growths may develop on the face, particularly around the cheeks and eyes. This pattern is called dermatosis papulosa nigra and is considered a type of seborrheic keratosis.

A growth can become red, swollen, crusted, itchy, or sore after rubbing, scratching, or catching on jewellery. Bleeding may occur after injury. A lesion that bleeds without an obvious injury, changes quickly, or looks different from your other spots should be assessed.

The exact cause of seborrheic keratoses is not known. They result from an overgrowth of keratinocytes, the main cells in the outer layer of the skin.

Age is the strongest known factor. The growths usually begin in adulthood, and people may develop more of them over the years.

They can run in families. If close relatives have many seborrheic keratoses, you may be more likely to develop them. Changes in certain cell-growth genes have been found within some lesions, but seborrheic keratosis is not usually treated as a simple inherited condition.

Sun exposure may contribute to growths on exposed skin, but seborrheic keratoses also occur in areas that receive little sun. Sunlight does not fully explain why they develop.

Pregnancy and some medical treatments have occasionally been linked to a temporary increase in growths, but these are not common causes. The condition does not result from poor hygiene, infection, or contact with another person.

A healthcare professional can often identify a seborrheic keratosis by examining its shape, color, surface, and edges. They may also compare it with other marks on your skin.

A dermatoscope may be used. This is a handheld magnifying device with a special light that shows structures below the skin’s surface. It can help distinguish a seborrheic keratosis from a mole, wart, or skin cancer.

Some seborrheic keratoses resemble melanoma, a potentially serious form of skin cancer. Dark color alone does not mean a growth is dangerous, but appearance cannot always provide certainty.

If the diagnosis is unclear, part or all of the growth may be removed for a biopsy. During a biopsy, tissue is examined under a microscope by a pathologist. This can confirm the type of growth and rule out cancer.

A routine skin examination may be enough for a long-standing, unchanged growth with typical features. A new or changing lesion deserves closer assessment rather than attempted removal at home.

Treatment is not medically necessary when the diagnosis is clear and the growth is not causing problems. Leaving it alone does not make it more likely to become cancerous.

Removal may be reasonable if a growth:

• Regularly catches on clothing, a comb, or jewellery
• Becomes itchy, inflamed, or repeatedly injured
• Makes shaving or skin care difficult
• Causes distress because of its appearance
• Needs laboratory examination to confirm the diagnosis

Several removal methods are available. The choice is based on the growth’s thickness, size, location, and color, as well as your skin type and the need for a biopsy.

Cryotherapy freezes the growth, usually with liquid nitrogen. It works best for thinner lesions. The treated area may blister or crust before healing.

Curettage removes the growth by gently scraping it from the skin after local anaesthetic has numbed the area. Electrosurgery uses an electrical current to destroy or control bleeding from the tissue. These methods may be combined.

A shave removal uses a small blade to remove a raised growth at skin level. It can also provide tissue for examination under a microscope. Some lesions may be treated with laser procedures, depending on the setting and available expertise.

Removal can leave a lighter or darker mark, especially in deeply pigmented skin. Scarring, infection, incomplete removal, and recurrence at the same site are possible, although serious problems are uncommon. A removed growth usually does not return, but new ones may develop elsewhere.

Do not cut, burn, or scrape off a suspected seborrheic keratosis yourself. Wart treatments and strong acids can injure normal skin, and self-treatment may delay the diagnosis of a growth that only resembles seborrheic keratosis.

Seborrheic keratoses are not considered precancerous. Their main complications come from irritation, uncertainty about the diagnosis, or treatment.

A raised growth can become inflamed when it rubs against clothing or is scratched. This may cause swelling, crusting, tenderness, or minor bleeding.

A more important concern is mistaken identity. Melanoma, squamous cell carcinoma, basal cell carcinoma, and some harmless moles can resemble seborrheic keratosis. A cancer can also occasionally develop beside an existing growth. This is why a lesion with unusual or changing features may need a biopsy.

Removal may cause temporary soreness, crusting, or a change in skin color. Less commonly, infection or a permanent scar develops.

A sudden appearance of many itchy seborrheic keratoses is sometimes called the sign of Leser-Trélat. It has been reported alongside internal cancers, but the association is debated because new growths are also common with age. A sudden widespread eruption should be assessed, but it does not mean that you have cancer.

There is no proven way to prevent seborrheic keratoses. Age and inherited tendency cannot be changed, and sun protection has not been shown to prevent all of these growths.

Protecting your skin from excessive ultraviolet exposure is still important because it lowers sun damage and helps prevent other skin conditions, including some skin cancers. This includes seeking shade, wearing protective clothing, and using sunscreen on exposed skin.

Regularly becoming familiar with your skin can help you notice new or changing growths. This does not prevent seborrheic keratoses, but it can make it easier to identify a spot that needs assessment.

Seborrheic keratoses usually remain harmless throughout life. An individual growth may stay similar for years or slowly become larger, darker, or thicker.

Many people develop additional growths over time. Removing existing lesions does not stop new ones from forming elsewhere. This can be frustrating, but it does not mean the condition is spreading through the body.

You can usually wash, moisturize, exercise, swim, and carry out normal activities without restriction. If a growth catches repeatedly, looser clothing or avoiding jewellery over the area may reduce irritation until it can be assessed.

Try not to pick at the surface. A partly detached or injured growth can bleed and become inflamed. If a lesion is in a difficult place, such as beneath a bra strap, waistband, or shaving area, removal may improve comfort.

It can be useful to photograph a noticeable lesion with a date and size reference. Photographs do not replace an examination, but they may help show whether a spot has changed.

After removal, follow the wound-care instructions you receive. Healing time and the final skin color depend on the method used, the body area, and your skin’s tendency to scar or develop pigment changes.

Arrange a routine appointment if you have a growth that may be a seborrheic keratosis but has not been identified before. Assessment is also reasonable if it repeatedly catches, itches, or affects how you feel about your appearance.

Seek a prompt appointment for a lesion that:

• Grows or changes noticeably over weeks or months
• Has several colors or an irregular border
• Bleeds without being scratched or injured
• Does not heal after crusting or bleeding
• Becomes persistently painful
• Looks clearly different from your other growths
• Appears as part of a sudden widespread outbreak

These features do not prove that a growth is cancerous. They mean that looking at it more closely is important.

Seborrheic keratosis itself is not an emergency. Seek urgent care after removal if there is spreading redness with fever, worsening pain with pus, or other signs of a significant infection.

Emergency care is rarely needed. Get immediate help if bleeding is heavy or does not stop after firm, continuous pressure, particularly if you take medicine that affects blood clotting.

Is seborrheic keratosis cancer?

No. It is a benign skin growth and is not considered precancerous. However, some skin cancers can look similar. A new, unusual, or changing lesion may need examination or biopsy.

Can I remove a seborrheic keratosis at home?

Home removal is not recommended. Cutting, scraping, freezing, or applying wart treatments can cause burns, infection, bleeding, and scarring. It can also delay the diagnosis of a different type of growth.

Will a seborrheic keratosis fall off by itself?

It may partly flake or come away after rubbing or injury, but most do not disappear completely without treatment. A damaged lesion can also become inflamed or bleed.

Why am I suddenly getting more of them?

People often develop more with age, and they may seem to appear in groups. Family tendency can also play a part. A genuinely sudden widespread outbreak, especially with intense itching, should be assessed.

Does removing one make more grow?

No. Removal does not cause other seborrheic keratoses. New growths may continue to appear because of age and personal tendency, not because an earlier one was treated.

Can seborrheic keratosis come back after removal?

A completely removed growth usually does not return, although incomplete removal can leave some tissue behind. New seborrheic keratoses can develop nearby or elsewhere.