Keratoacanthoma

Overview

A keratoacanthoma (say: ker-uh-toh-ak-an-THOH-muh) is a skin growth that usually appears on sun-exposed skin. It often starts as a small, firm bump and grows quickly over a few weeks. It may look like a dome with a hard, horny center or a small crater. Doctors do not fully agree on whether it is a harmless growth or a very low-risk type of skin cancer. Because it can look like a more serious skin cancer, it is usually checked carefully and often removed. Some may shrink on their own, but doctors cannot predict which ones will do this.

It is not common. It is seen most often in people with sun-damaged skin, especially older adults.

It can affect anyone, but it is more likely in people with fair skin, a lot of sun exposure, older age, or a weakened immune system. It is rare in children.

Symptoms

Common symptoms

• A firm, dome-shaped lump on the skin
• Skin-coloured, pink, red, or slightly brown
• A central dip or crater filled with a hard, horny plug
• Fast growth over a few weeks
• May itch, feel tender, or be painless
• May bleed, crust, or form an open sore

Symptoms in children

• Keratoacanthoma is rare in children. Any new skin lump in a child should be checked by a doctor, especially if it grows quickly, bleeds, or hurts.

Symptoms in older adults

• It is more common in older adults, especially on skin that has had many years of sun exposure. It can grow quickly over a few weeks, so a new lump should be checked rather than watched for a long time.

Causes

Main causes

• Ultraviolet (UV) light from the sun or tanning beds is the main known trigger.
• It often starts in skin that has been damaged by many years of sun exposure.
• Some cases may follow injury or inflammation of the skin, but this is not fully understood.

Risk factors

• Fair skin that burns easily
• Older age
• A lot of sun exposure or a history of sunburn
• A weakened immune system
• Rare genetic skin conditions
• Male sex

When to see a doctor

See a doctor urgently if:

• A new skin lump that grows quickly, bleeds, or forms a crater
• A spot that is painful, infected, or changing fast
• Any new skin growth in a child

Book a routine appointment if:

• A new or changing skin spot that worries you
• A growth that has not healed after a few weeks
• Many sun-damaged spots or a history of skin cancer

Diagnosis

A GP or skin specialist will ask about the growth and look at it. They may use a special lighted magnifier called a dermatoscope. Because keratoacanthoma can look very much like a type of skin cancer called squamous cell carcinoma, a biopsy is often needed to be sure.

Tests that may be done

• A skin exam, sometimes with a special magnifier called a dermatoscope
• A skin biopsy (a small sample sent to a lab)
• In some cases, a specialist may arrange other tests if the growth is large or deep

What to expect at your appointment

You may have a small procedure with local anaesthetic to take a sample. Results usually take days to a couple of weeks. You will be told how to care for the area and when to return.

Treatment

Treatment is planned by a doctor. The main aims are to confirm the diagnosis, remove the growth, and reduce scarring. Not every skin lump needs the same treatment.

Self-care at home

• Do not squeeze, pick, scratch, or cut the growth.
• Keep the skin protected from the sun.
• If you have a procedure, follow your care team's wound-care advice.
• Attend follow-up appointments.
• Check your skin regularly and ask for help with any new or changing spot.

Medical treatments

Treatment depends on the size, site, and whether the diagnosis is certain. Options include surgical removal, scraping and heat treatment, or careful observation by a skin specialist in selected cases. Specialists may use other techniques in some situations. You will be given advice about wound care and follow-up. No single treatment is right for everyone.

When is surgery considered?

Surgery is often recommended. It removes the growth, provides a sample for the lab, and lowers the chance of scarring or coming back. The procedure is usually done with local anaesthetic. Your doctor will explain the options.

Living with this condition

After treatment, keep the area clean and protected as advised. It may leave a scar that fades over time. Use sun protection every day and check your skin for new or changing spots.

Lifestyle tips

• Use a high-factor broad-spectrum sunscreen and reapply it when outdoors.
• Wear a hat, clothing, and seek shade during strong sun.
• Avoid sunbeds and tanning.
• Do not smoke; smoking harms skin healing.
• Keep skin healthy and see your doctor about any new growth.

Diet and exercise

No special diet or exercise plan treats keratoacanthoma. A healthy diet and regular activity support general health and healing.

Mental health and emotional wellbeing

It is normal to feel worried when you find a new skin growth or hear the word cancer. Ask your doctor to explain what is known and what will happen next. If you feel very anxious or low, tell your GP. If you have thoughts of harming yourself, contact your local emergency number or a local crisis service right away.

Prevention

You cannot prevent every keratoacanthoma, but you can lower your risk by protecting your skin from UV light.

Vaccines

There is no vaccine for keratoacanthoma.

Screening programmes

There is no routine screening programme for keratoacanthoma. If you have a lot of sun exposure, fair skin, or many skin spots, ask your doctor about skin checks.

Complications

If left untreated

• It may grow large and damage nearby skin.
• It may leave a scar, even if it goes away on its own.
• It may bleed, crust, or become infected.
• It cannot be reliably told apart from a type of skin cancer without a biopsy.

Long-term outlook

Most people do well after treatment. Keratoacanthoma is often cured with removal, and follow-up helps catch any new skin changes early. If you are worried, ask your doctor for a clear plan.

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