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Undifferentiated pleomorphic sarcoma (UPS) is a rare cancer. It starts in the body’s soft tissues, like muscles, fat or nerves. It usually shows up in the arms or legs, but it can also be found in the trunk or the area behind the belly.
The name describes how the cancer cells look under a microscope. “Undifferentiated” means the cells do not look like normal body tissues. “Pleomorphic” means the cells grow in many different shapes and sizes. This cancer can grow quickly and has a high chance of spreading to other parts of the body, mostly the lungs.
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Symptoms and Signs
The most common sign of undifferentiated pleomorphic sarcoma is a lump or swelling that gets bigger. Because these tumors often do not cause pain at first, they might already be large by the time they are discovered.
As the tumor gets bigger, it can press on nearby nerves or muscles, which might lead to pain, tingling or numbness. If the cancer is in the abdomen, a person might feel stomach pain. Or they might lose their appetite or have constipation. Other signs can include having a fever or losing weight without trying.
Causes and Risk Factors
Researchers are not exactly sure what causes this cancer. However, they know it starts when there’s a change in a cell’s DNA. When this happens, it causes the cell to grow out of control and form a tumor.
While anyone can get undifferentiated pleomorphic sarcoma, it is most common in adults between 50 and 70. Most of the time, it happens for no known reason. However, some factors might increase the risk, such as having radiation treatment in the past or having a history of chronic tissue injury, like old surgical scars.
Undifferenitaed Pleomorphic Sarcoma Care Team
At Fred Hutch, we offer comprehensive treatment from a team of experts who specialize in soft tissue sarcomas and bone cancers.
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Diagnosing Undifferentiated Pleomorphic Sarcoma
To find out if a lump is cancer, a physician will order imaging tests like an MRI to see where the tumor is located and the size. Since this cancer has a high risk of spreading, they also use CT scans of the chest to check the lungs.
The most important step for a final diagnosis is a biopsy. This is when a physician takes a tiny piece of the tumor and sends it to a lab for analysis. Because these cancer cells can look like the cells of many other diseases, special lab tests are needed, to rule out other options before a diagnosis can be made.
Learn more about diagnosing and staging sarcoma.
Treating Undifferentiated Pleomorphic Sarcoma
The main way to treat this cancer is with surgery to remove the entire tumor. Surgeons remove the cancer along with a small edge of healthy tissue to make sure no cancerous cells are left.
Many patients also get radiation therapy before or after their surgery to help shrink the tumor or destroy any leftover cancer cells. This helps keep undifferentiated pleomorphic sarcoma from coming back. If the cancer is very large or has spread, a physician might use chemotherapy or newer drug options. It is very important to have regular check-ups after treatment because undifferentiated pleomorphic sarcoma can return.
Learn more about treating sarcoma.