Keratoacanthoma is a dome-shaped lump or tumor that grows on your skin. Once you spot it, it’s important to talk to your doctor. It sometimes happens to people before they get squamous cell carcinoma, the second most common type of skin cancer.
Keratoacanthoma Symptoms
You might think you have a pimple or boil at first, but keratoacanthoma can grow fast and get as big as a quarter in a couple of months.
It looks like a small, red or skin-colored volcano – there’s a distinctive crater at the top of the lump that often has keratin, or dead skin cells, inside.
You’ll usually see keratoacanthoma on skin that’s been exposed to the sun, like your head, neck, arms, the backs of your hands, and sometimes your legs. It often starts in a hair follicle.
Who Gets Keratoacanthoma?
Men are twice as likely to have the condition as women. It’s also more common in white people than in those with darker skin and people aged 60 or older. It’s rare for anyone younger than 20 to have keratoacanthoma.
Doctors don’t know what causes keratoacanthoma, but some things make you more likely to get it:
- Sun exposure
- HPV infection
- Some cancer-causing chemicals
- Your genes
- A weak immune system
Getting a Diagnosis
Your doctor will probably take a biopsy, or a piece of the tumor, to send to an expert called a dermatopathologist, who will examine the sample under a microscope. The cells of keratoacanthoma often look just like those of squamous cell carcinoma. Your doctor will have to remove a large enough piece so the pathologist can see the shape of the tumor with its distinctive crater.
Treatments for Keratoacanthoma
The most common treatment is surgery to remove the keratoacanthoma. You can have the procedure in your doctor’s office with medicine to numb the area around the tumor.
There are a few different surgeries your doctor may use. They can:
- Scrape off the tumor and seal up the wound.
- Apply liquid nitrogen to freeze and destroy the tumor. This is called cryosurgery.
- Cut the tumor out and use stitches to close the area.
- Remove one layer of tissue at a time and examine each one under a microscope to ensure all abnormal cells are gone. This is called Mohs surgery. It’s the most precise way to get rid of keratoacanthoma — but also the most expensive.
If you can’t have surgery or if you have multiple keratoacanthomas, you can try other treatments:
- The chemotherapy drug 5-fluorouracil. You can get it as a cream to rub on your skin or as a shot.
- Injections of the chemotherapy drugs bleomycin or methotrexate
- Radiation
- Drugs such as retinoids that you take by mouth
It’s not unusual for a single keratoacanthoma to shrink and disappear on its own after several months. But it may leave a worse scar than one from surgery. It could also come back, so it’s best to get it removed.
If you don’t treat it, keratoacanthoma can spread throughout your body.
How to Prevent Keratoacanthoma
Once you’ve had one keratoacanthoma, you may be more likely to get others in the future. Check your skin regularly for any lumps or unusual spots, and see your doctor for a full-body exam twice a year.
It’s also important to protect your skin from sun damage.
- Avoid going outside from 10 a.m. to 4 p.m. — when the sun is strongest.
- Use a broad-spectrum sunscreen with zinc oxide as the main ingredient (at least 8%) and an SPF of 15 or higher.
- Wear sun-protective clothing and hats when you’re outside.
- Don’t use tanning beds.
Conditions Related to Keratoacanthoma
These conditions are extremely rare but can cause multiple keratoacanthomas to grow on your skin. There can be so many that doctors can’t remove them all with surgery.
Ferguson-Smith syndrome can cause as many as 100 keratoacanthomas at one time. It’s the most common type of multiple keratoacanthoma. It’s a condition you can get through your genes and may start as early as age 8.
You may take retinoid medicine to try to reduce the number of additional tumors.
Grzybowski syndrome is even rarer. It causes tumors that are smaller but itch intensely. They may even show up in the mouth.
Keratoacanthoma FAQs
Is keratoacanthoma cancer?
Not exactly. Keratoacanthoma is usually considered a benign (noncancerous) skin tumor that can sometimes go away on its own. But it looks very similar under the microscope to squamous cell carcinoma (a type of skin cancer) and can behave like it. Because of this similarity, doctors often treat it as if it were cancer.
How long does a keratoacanthoma take to heal?
After your doctor removes the bump, it usually takes a couple of weeks to heal. Doctors say it’s important to keep follow-up appointments to make sure your skin heals well and to make sure the tumor was completely removed. The doctor will also want to watch you, just in case keratoacanthoma comes back.
What is the progression of keratoacanthomas?
First, the tumor grows fast — normally over six to eight weeks. Then, the tumor stops growing and — over a few weeks or months — it will form a crater-like center, kind of like a volcano with a small plug in it. After a while, the tumor slowly gets smaller. It might flatten out and heal on its own.
