A Marjolin ulcer is a rare and aggressive type of skin cancer that can form from burn scars or other poorly healing wounds.

It’s named for the 19th-century French surgeon Jean Nicolas Marjolin, who first described these specific, cancerous changes in scar tissue.

Occasionally, a Marjolin ulcer may be referred to as a burn ulcer.

In the early stages, Marjolin ulcers present as a flat, hard sore at the site of a scar or burn that’s refusing to heal, usually for 3 months or more. They can sometimes start off as a small blister forming over an old scar.

After the sore forms, you may also notice:

  • foul-smelling pus
  • severe pain
  • bleeding
  • crusting

Marjolin ulcers can repeatedly close and reopen. They may continue to grow after the initial sore forms.

Marjolin ulcers grow from damaged skin, often in an area of skin that’s been burned. It’s estimated that about 2 percent of burn scars develop Marjolin ulcers.

They can also develop from:

Doctors don’t quite know why these areas of skin damage turn cancerous in some people. There are two main theories:

  • The injury destroys blood vessels and lymphatic vessels that are part of your body’s immune response, making it harder for your skin to fight off cancer.
  • Long-term irritation causes skin cells to constantly repair themselves. During this renewal process, some skin cells become cancerous.

Men are more likely to develop a Marjolin ulcer than women, possibly because of the higher rate of burns in that population.

The risk of developing a Marjolin ulcer is equal across all races and ethnicities — which differentiates it from other skin cancers.

Most Marjolin ulcers are squamous cell cancers. That means they form in squamous cells in the upper layers of your skin. However, they’re sometimes basal cell tumors, which form in deeper layers of your skin.

Typically, Marjolin ulcers grow very slowly, usually taking 30 to 35 years to turn cancerous.

If you have a sore or scar that hasn’t healed after 3 months, a primary care doctor might refer you to a dermatologist after an exam of your skin.

If the dermatologist thinks the sore could be cancerous, they’ll likely perform a biopsy. To do this, they’ll remove a small tissue sample from the wound and test it for cancer.

Your surrounding lymph nodes may be examined via ultrasound. If something suspicious is detected, the lymph node near the sore may be removed and tested for cancer to see whether it’s spread. This is known as a sentinel lymph node biopsy.

Depending on the results of the biopsy, your doctor might also use a CT scan or MRI scan to make sure it hasn’t spread to your bones or other organs.

Treatment usually involves surgery to remove the tumor. A surgeon can use a few different methods to do this, including:

  • Excision. This method involves cutting out the tumor and some of the tissue around it.
  • Mohs surgery. This surgery is done in stages. First, your surgeon will remove a layer of skin and look at it under a microscope while you wait. This process is repeated until there are no cancer cells left.

After surgery, you’ll need a skin graft to cover the area where the skin was removed.

After treatment, you’ll need to follow up with your doctor regularly to make sure the cancer hasn’t returned.

If you have a large open wound or severe burn, make sure you get emergency medical treatment. This can help to reduce your risk of developing a Marjolin ulcer or serious infection.

Also, be sure to get medical attention for any sores or burns that don’t seem to be healing after 2 to 3 weeks.

If you have an old burn scar that starts to develop a sore, tell a doctor as soon as possible. You may need a skin graft to prevent the area from developing a Marjolin ulcer.

If you notice that a scar or burn isn’t healing, talk with a doctor or other healthcare professional as soon as possible, as a variety of conditions could be causing the issue.

Because Marjolin ulcers take so long to form, getting treatment as soon as possible is essential. This means you should take anything that looks like an infected wound around a scar or burn seriously.

Marjolin ulcers are a very serious form of skin cancer. Your outlook depends on the size of your tumor and how aggressive it is.

The 3-year survival rate for a Marjolin ulcer ranges from 65 to 75 percent. This means that 65 to 75 percent of people diagnosed with a Marjolin ulcer are still alive 3 years after being diagnosed.

In addition, Marjolin ulcers can return, even after they’ve been removed. If you’ve previously had a Marjolin ulcer, make sure you regularly follow up with a doctor and tell them about any changes you notice around the affected area.