Undifferentiated pleomorphic sarcoma


Undifferentiated pleomorphic sarcoma (UPS) is a rare type of cancer that begins mostly in the soft tissues of the body. Soft tissues connect, support and surround other body structures.

UPS usually occurs in the arms or legs. Less often it can happen in the area behind the abdominal organs (retroperitoneum).

The name undifferentiated pleomorphic sarcoma comes from the way the cancer cells appear under the microscope. Undifferentiated means the cells don't look like the body tissues in which they develop. The cancer is called pleomorphic (plee-o-MOR-fik) because the cells grow in multiple shapes and sizes.

Treatment for UPS depends on the location of the cancer, but often involves surgery, radiation and drug treatments.

UPS used to be called malignant fibrous histiocytoma.


Undifferentiated pleomorphic sarcoma symptoms depend on where the cancer occurs. It most often happens in the arms and legs, but it can happen anywhere in the body.

Signs and symptoms may include:

  • Growing lump or area of swelling.
  • If it grows very large, there may be pain, tingling and numbness.
  • If it occurs in an arm or leg, there may be swelling in the hand or foot of an affected limb.
  • If it occurs in the abdomen, there may be pain, loss of appetite and constipation.
  • Fever.
  • Weight loss.

When to see a doctor

Make an appointment with a doctor if you develop any persistent signs or symptoms that worry you.


It's not clear what causes undifferentiated pleomorphic sarcoma.

Doctors know this cancer begins when a cell develops changes in its DNA. A cell's DNA contains the instructions that tell a cell what to do. The changes tell the cell to multiply rapidly, creating a mass of abnormal cells (tumor). The cells can invade and destroy nearby healthy tissue. In time, the cancer cells can break away and spread (metastasize) to other parts of the body, such as the lungs and bones.

Risk factors

Factors that may increase the risk of undifferentiated pleomorphic sarcoma include:

  • Older age. This cancer tends to occur in adults older than 50, though it can occur at any age.
  • Previous radiation therapy. Rarely, this cancer can develop in an area of the body that was previously treated with radiation therapy.

Most people who develop undifferentiated pleomorphic sarcoma have no known risk factors, and many people who have risk factors never develop the cancer.


Diagnosis for undifferentiated pleomorphic sarcoma usually starts with a review of your symptoms and a physical examination. This cancer is often diagnosed after other types of cancer have been ruled out.

Tests and procedures may include:

  • Physical exam. Your doctor will ask you questions about when your symptoms began and if they've changed over time. He or she will examine the area to better understand the size and depth of the growth, whether it's connected to nearby tissues, and whether there are any signs of swelling or nerve damage.
  • Imaging tests. Your doctor may recommend imaging tests to create pictures of the affected area and understand more about your condition. Imaging tests may include X-rays, CT, MRI and positron emission tomography (PET) scans.
  • Removing a sample of tissue for testing (biopsy). To make a definitive diagnosis, your doctor collects a sample of the tumor tissue and sends it to a lab for testing. Depending on your particular situation, the tissue sample may be collected with a needle inserted through your skin or during an operation.

    In the lab, doctors trained in analyzing body tissues (pathologists) examine the sample to determine the types of cells involved and whether the cells are likely to be aggressive. This information helps rule out other types of cancer and guides your treatment.

Determining the type of biopsy needed and the specifics of how it should be performed requires careful planning by the medical team. Doctors need to perform the biopsy in a way that won't interfere with future surgery to remove the cancer. For this reason, ask your doctor for a referral to a team of experts with extensive experience in treating soft tissue sarcomas before the biopsy.


Treatment for undifferentiated pleomorphic sarcoma usually involves surgery to remove the cancer cells. Other options include radiation therapy and drug treatments (systemic therapies), such as chemotherapy, targeted therapy and immunotherapy. Which treatments are best for you will depend on the size and location of your cancer.


When possible, doctors try to remove the sarcoma completely with surgery. The goal is to remove the cancer and a margin of healthy tissue around it with as minimal an impact as possible.

When the cancer affects the arms and legs, surgeons prefer to use limb-sparing operations. However, in some cases it may be necessary to amputate the affected arm or leg. Other treatments, such as radiation therapy and chemotherapy, might be recommended before surgery to shrink a cancer so that it's easier to remove without amputating the affected limb.

Radiation therapy

Radiation therapy uses high-powered beams of energy, such as X-rays or protons, to kill cancer cells. Radiation therapy can be given as:

  • External beam radiation. This type of radiation comes from a machine that moves around you as you lie on a table. The machine directs the radiation to precise points on your body.

    Radiation may be used before surgery to shrink a sarcoma and make it easier to remove. It may also be used after surgery to kill any cancer cells that remain.

  • Intraoperative radiation therapy (IORT). IORT is used during surgery just after the cancer is removed. The radiation is directed to the area around where the cancer used to be. IORT might be recommended if the cancer is located in an area that makes it difficult to remove the cancer completely during surgery.


Chemotherapy is a drug treatment that uses chemicals to kill cancer cells. It can be administered by pill or through a vein (intravenously), or both.

Chemotherapy is most often used to treat undifferentiated pleomorphic sarcoma that comes back after initial treatment or that spreads to other areas of the body.

Sometimes chemotherapy is used before surgery to shrink the cancer so that it's easier to remove during an operation.

Chemotherapy may also be combined with radiation.

Targeted drug therapy

Targeted drug treatments focus on specific abnormalities present within cancer cells. By blocking these abnormalities, targeted drug treatments can cause cancer cells to die.

For undifferentiated pleomorphic sarcoma, targeted therapy drugs may be combined with chemotherapy.

Some targeted therapies only work in people whose cancer cells have certain genetic mutations. Your cancer cells may be tested in a laboratory to see if these drugs might help you.


Immunotherapy uses your immune system to fight cancer. Your body's disease-fighting immune system may not attack your cancer because the cancer cells produce proteins that help them hide. Immunotherapy works by interfering with that process.

Immunotherapy treatments are generally reserved for people with advanced cancer.

IORT for a thigh sarcomaIORT dosage can be much higher than for standard radiation therapy given from the outside of the body.

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Alternative medicine

No alternative treatments have been found helpful in treating undifferentiated pleomorphic sarcoma. But some complementary and alternative treatments may relieve the symptoms you experience due to cancer or cancer treatment.

Alternative treatments that may help relieve symptoms include:

  • Acupuncture.
  • Exercise.
  • Massage.
  • Meditation.
  • Music therapy.
  • Relaxation exercises.

Coping and support

A diagnosis of cancer such as undifferentiated pleomorphic sarcoma can be overwhelming. With time you'll find ways to cope with the distress and uncertainty of cancer. Until then, you may find it helps to:

  • Learn enough about sarcoma to make decisions about your care. Ask your doctor about your sarcoma, including your treatment options and, if you like, your prognosis. As you learn more about undifferentiated pleomorphic sarcoma, you may become more confident in making treatment decisions.
  • Keep friends and family close. Keeping your close relationships strong will help you deal with your diagnosis and care implications. Friends and family can provide the practical support you'll need, such as helping take care of your home if you're in the hospital. And they can serve as emotional support when you feel overwhelmed by cancer.
  • Find someone to talk with. Find a good listener who is willing to listen to you talk about your hopes and fears. This may be a friend or family member. The concern and understanding of a counselor, medical social worker, clergy member or cancer support group also may be helpful.

    Ask your doctor about support groups in your area. Or check your phone book, library or a cancer organization, such as the National Cancer Institute or the American Cancer Society.

Preparing for an appointment

If your family doctor suspects you have undifferentiated pleomorphic sarcoma, you'll likely be referred to a cancer doctor (oncologist) who specializes in sarcomas. Undifferentiated pleomorphic sarcoma is rare and often requires complex care. It's best treated by someone who has significant experience with it, which often means an academic or multispecialized cancer center.

Because appointments can be brief, and there's often a lot of information to discuss, it's a good idea to arrive well prepared. Here's some information to help you get ready.

What you can do

  • Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
  • Make a list of all medications, vitamins or supplements that you're taking.
  • Ask a family member or friend to come with you. Sometimes it can be difficult to remember all the information provided to you during an appointment. Someone who accompanies you may remember something that you missed or forgot.
  • Write down questions to ask your doctor.

Your time with your doctor is limited, so preparing a list of questions can help you make the most of your time together. List your questions from most important to least important in case time runs out. For undifferentiated pleomorphic sarcoma, some basic questions to ask your doctor include:

  • Do I have cancer?
  • Are there other possible causes for my symptoms?
  • What kinds of tests do I need to confirm the diagnosis? Do these tests require any special preparation?
  • What stage is the sarcoma?
  • What treatments are available for undifferentiated pleomorphic sarcoma, and which do you recommend?
  • Can the sarcoma be removed?
  • What types of side effects can I expect from treatment?
  • Are there any alternatives to the primary approach that you're suggesting?
  • I have other health conditions. How can I best manage these conditions together?
  • Are there any dietary or activity restrictions that I need to follow?
  • What's my prognosis?
  • Are there any brochures or other printed material that I can take with me? What websites do you recommend?
  • Should I get additional treatments such as radiation therapy either before or after an operation?
  • Is the surgeon you're recommending experienced in this specific type of cancer operation?

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may make time to cover other points you want to discuss. Your doctor may ask:

  • When did you first notice your signs and symptoms?
  • Are you experiencing pain?
  • Does anything seem to improve your symptoms?
  • What, if anything, appears to worsen your symptoms?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask other questions.

Content From Mayo Clinic Updated: 12/29/2023
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