Malignant mesenchymoma | Sarcoma UK
Make a Donation

Get support

Malignant mesenchymoma

Malignant mesenchymoma is a very rare type of cancer called a sarcoma. It:

  • often grows in soft tissues, blood vessels, or organs like the intestines
  • mostly affects middle-aged adults
  • is often found in the thigh or the area at the back of the tummy.

Malignant mesenchymoma forms when stem cells (the building blocks of the body) don’t develop properly into different cell types. It contains a mix of underdeveloped cells that should have become things like muscle, bone or fat cells.


There are an average of 4 cases of malignant mesenchymoma diagnosed every year in England.

It makes up 0.1% of all soft tissue sarcomas.

For more information on these statistics, you can visit our soft tissue sarcoma data hub.

Signs and symptoms

Symptoms can vary depending on the size and location of your tumour. Common symptoms include:

  • a painless lump or swelling that grows quickly, often in the legs, arms, head, neck or tummy area
  • pain
  • swelling
  • loss of appetite
  • constipation
  • fever
  • weight loss

Children may have swelling in the tummy and pain, with or without a lump. They often have fever and weight loss too.


A specialist will diagnose malignant mesenchymoma with tests. You might have:

  • a physical examination – to check any lump
  • a scan – taking pictures of the inside of the body. Scans might include an ultrasound, CT, or MRI scans
  • a biopsy – taking and testing a sample of the tumour. A doctor will look to see if the biopsy looks like malignant mesenchymoma.

To read more about these scans and tests, click here.



The first treatment for malignant mesenchymoma is surgery. If you have surgery, your surgeon will remove the tumour. They’ll also aim to take out an area of normal tissue too. Sometimes people call this ‘taking a margin’. They do this to make sure they remove all of the cancer.

If your tumour is in your arms or legs, your surgeon will perform ‘limb-sparing surgery’. They do this to make sure the limb can continue to work well.

If the cancer has spread, your surgeon may need to perform a partial or full amputation to stop the cancer – although this is very rare.



Radiotherapy is a treatment that uses radiation to kill cancer cells.

You might have it before or after surgery. When used before surgery, it aims to make the tumour smaller so that it’s easier to remove. When used after surgery, it aims to kill off any cancer cells left after your operation.



Chemotherapy is a treatment that uses medicine to kill cancer cells.

It’s sometimes used if:

  • you have a high risk of the cancer coming back
  • your tumour has spread to other parts of the body (also known as metastasis).

It’s not clear how well chemotherapy works for people with malignant mesenchymoma. This is because this type of sarcoma can be very broad and results from multiple different types of cells. You may be more likely to have surgery (with or without radiotherapy) as your main treatment.


Targeted and experimental therapies

Researchers are learning more about treatments called targeted therapies and immunotherapies.

Targeted therapies are drugs that find and attack cancer cells. They work by targeting the differences a cancer cell has from normal cells. They do this to stop them from growing and spreading.

Immunotherapy is a type of treatment that uses your immune system to find and attack cancer cells.

You may be offered a chance to join a trial. These trials can find new ways to diagnose and treat cancer. Some studies also look at the care and well-being of patients. Your doctor can give you more information on opportunities to take part in a trial.

After treatment

After treatment, you’ll have follow-up appointments for several years. Your sarcoma nurse will provide a schedule. The follow-ups will usually include:

  • a chance to discuss symptoms
  • an examination to look for any signs of the cancer returning
  • a chest x-ray to rule out any secondary cancers in the lungs

Living with

Malignant mesenchymoma can come back after treatment. If it reappears in the same area as the original tumour, it’s known as a local recurrence.

If the cancer does reappear, it’s important to get treated quickly. You may have surgery and/or radiotherapy. Your treatment plan will be determined by your doctor.

It’s also useful to check for recurrences by examining your body. Your doctor or nurse will tell you what to look for.

If you’re worried about your cancer returning, you can talk to your doctor or nurse. They might decide to bring your follow-up appointment forward.

What if my cancer spreads to another part of my body?

If your cancer returns, it can be accompanied by cancer in other parts of your body. This is called ‘metastasis’ or ‘secondary cancer’.

Some people are diagnosed with sarcoma because their metastases has been found before the first tumour. In people with malignant mesenchymoma, these secondary cancers can appear in the lungs, which is why a chest x-ray is taken at follow-up appointments.

Secondary cancers can also appear in the bones, lymph nodes, and other parts of the body. Treatment for secondary cancer can involve surgery or radiotherapy. It can also involve other treatment as needed.

If you have any questions or if you need to talk to someone, our Support Line team are here for you.

Last reviewed: 28 May 2024

Next review due: 28 May 2027


Popular search terms