Undifferentiated Pleomorphic Sarcoma

Undifferentiated pleomorphic sarcoma (UPS) is a type of soft tissue sarcoma. It usually starts in the soft tissues of your arms or legs, or the back part of your belly (retroperitoneum). Rarely, UPS can affect your bones. It’s typically aggressive, so it can spread to other areas of your body — usually to your lungs or lymph nodes.

The original name for UPS was malignant fibrous histiocytoma. That’s because researchers thought this type of cancer formed in specialized immune cells called histiocytes. But later research suggested that it likely starts in mesenchymal cells that form connective tissue. The term “undifferentiated” refers to the fact that the cancer cells are very disorganized.

“Pleomorphic” means that the cells vary in size, shape or nuclei (the structure in a cell that contains chromosomes). In other words, UPS cells grow very haphazardly.

Overall, UPS is rare, affecting fewer than 5,000 people in the U.S. But it’s one of the three most common soft tissue sarcomas, along with liposarcoma and leiomyosarcoma.

Symptoms of undifferentiated pleomorphic sarcoma

Undifferentiated pleomorphic sarcoma symptoms might include:

• A growing lump
• A painless lump or mass that may or may not move when you touch it
• Numbness or tingling if a lump or mass is pushing on or arising from a nerve
• Swelling in an arm or leg

UPS doesn’t always cause noticeable symptoms. It’s most often painless, doesn’t have any skin changes over the top and doesn’t typically cause symptoms like fever, weight loss or general malaise.

Undifferentiated pleomorphic sarcoma causes

Experts aren’t sure what causes undifferentiated pleomorphic sarcoma. They know it happens when healthy cells develop changes in their DNA, but they don’t know what causes those changes.

Risk factors

A risk factor is something that increases your chances of getting a condition. Known risk factors for UPS include:

• Being male (white males have the highest risk)
• Being over the age of 50
• Certain diseases like neurofibromatosis or Paget’s disease of bone
• Certain genetic disorders like Li-Fraumeni syndrome
• Exposure to certain chemicals like arsenic or vinyl chloride
• History of radiation therapy to the affected area
• Occupational radiation exposure

Most people who develop UPS don’t have any known risk factors.

How doctors diagnose undifferentiated pleomorphic sarcoma

Your healthcare provider will start by reviewing your health and biological family history. They’ll also ask questions about your symptoms, like when they started and whether they’ve changed over time. They’ll also do:

• A physical exam. They’ll check the size of the lump and feel its location and how hard it is.
• Imaging tests. These typically include X-rays, an ultrasound and/or an MRI.
• Biopsy. Your provider will take a small sample of tissue and send it to a pathologist for testing. This involves looking at the sample under a microscope.

How is UPS treated?

Undifferentiated pleomorphic sarcoma treatment depends on the size of the tumor and whether the cancer has spread. The main treatment for early-stage UPS is typically surgery to remove the growth, most often combined with radiation therapy. But you might need additional cancer treatments, too.

Surgery

Surgery for undifferentiated pleomorphic sarcoma involves removing the tumor. The goal is to remove the entire sarcoma and a little bit of the healthy tissue around it (known as “the margin”). Your surgeon does this to improve the chances of removing all the cancer cells. If cancer cells are at the edge of the removed tumor, there’s a risk that some may be left in your body as well.

If UPS affects your arms or legs, your surgeon will try to remove the cancer and preserve as much function as possible. But in some cases, amputation may be necessary. Ask your oncologist what type of treatment they recommend for your situation.

Additional cancer treatments

Oncologists may also use additional treatments before or after surgery. These treatments rarely shrink the tumor, but they can help make the tumors safer to remove at surgery or treat any remaining cancer cells after surgery:

• Chemotherapy
• Immunotherapy
• Radiation therapy

Your treatment plan is unique to you. Ask your oncologist about your options. You’ll likely have a multidisciplinary team, including a surgeon, a radiation oncologist and a medical oncologist. Each specialist has a specific role, but they all work together to treat you. They can help you determine what’s best in your situation.

When should I see my healthcare provider?

You should see a healthcare provider right away any time you notice a growing lump or mass — especially if it occurs with pain, swelling or limited range of motion.

If you already know you have UPS, tell your oncologist right away if you develop any new or worsening symptoms.

What can I expect if I have undifferentiated pleomorphic sarcoma?

Life expectancy varies depending on the size and stage of the sarcoma. The five-year survival rate for high-grade UPS is about 60%. That means that around 60% of people diagnosed with this condition are still alive five years later. The 10-year survival rate is 48%.

Survival rates are just estimates. They can’t tell you how long you’ll live or what kind of treatment will work for you. To learn more about UPS survival rates and how they affect you, talk to your oncology team.

Is undifferentiated pleomorphic sarcoma curable?

It’s possible to cure UPS, especially during the early stages. There still may be treatment options in later stages, which can prolong your quality of life. Like any type of cancer, early detection and treatment increase your chances for successful outcomes.