Undifferentiated Pleomorphic Sarcoma

Undifferentiated pleomorphic sarcoma (UPS) is a rare type of soft tissue sarcoma. It begins in the connective tissue, which supports and surrounds other parts of the body. UPS usually occurs in the arms or legs, but it can also start deep in the body, including the area behind the abdominal organs, called the retroperitoneum.

The name "undifferentiated" means the cancer cells look very abnormal and do not clearly resemble the tissue they came from. Like other soft tissue sarcomas, UPS can grow into nearby tissue and, in some cases, spread to other parts of the body.

Types & Stages

UPS is considered an undifferentiated high-grade pleomorphic sarcoma. "High-grade" means the cancer cells tend to grow and spread more quickly. Under a microscope, the cells look very irregular and vary widely in size and shape, which is what "pleomorphic" describes.

UPS is often described in simple terms based on how far it has spread:

• Localized. The cancer is found only where it started and has not spread to other parts of the body.
   
• Regional spread. The cancer has grown into nearby tissues or lymph nodes.
   
• Distant spread (metastatic). The cancer has spread to distant parts of the body, such as the lungs.

Your care team will use the tumor's size, grade, location, and whether it has spread to plan treatment.

Signs & Symptoms

UPS often causes few symptoms early on. When symptoms do appear, they can depend on where the tumor is located.

Visit a doctor if you are experiencing any of these symptoms:

• A lump or mass that is growing
• Pain in the area of the tumor
• Swelling in an arm, leg or other part of the body
• Abdominal fullness or discomfort when the tumor is deep in the body
• Pressure symptoms caused by the tumor pushing on nearby organs or nerves

Many lumps and symptoms are not cancer. Still, it is important to pay attention to your body. If symptoms are new, last more than a few weeks, or are unusual for you, talk with a healthcare provider.

Diagnosis

Tests and procedures used to diagnose UPS may include:

• Physical exam and history. Your doctor checks the lump and asks about your symptoms, how long it has been there, and your health history.
   
• Imaging tests. An MRI or CT scan can show the size, depth, and location of the tumor and whether it involves nearby tissue. These tests help guide the biopsy and surgery.
   
• Chest imaging. Imaging of the chest may be used to check whether the cancer has spread to the lungs.
   
• Biopsy. A biopsy removes a small sample of the tumor so it can be examined under a microscope by a pathologist. This is the only way to confirm UPS and learn more about it.

Treatment

Treatment for UPS depends on the tumor's size, grade, and location, whether it has spread, and your overall health. Surgery is the main treatment for most people.

Treatment may include:

• Surgery. When the tumor can be safely removed, surgery is the main treatment. The surgeon removes the tumor along with a margin of healthy tissue around it. The goal is to remove all of the cancer while keeping as much function as possible. Removing the tumor completely offers the best chance for cure.
   
• Radiation therapy. Radiation uses high-energy beams to kill cancer cells. It may be used before or after surgery in select cases, such as larger or higher-grade tumors, to help lower the chance that the cancer comes back.
   
• Chemotherapy. Chemotherapy uses medicines to kill cancer cells or slow their growth. It may be considered in select cases, depending on the tumor's size, grade, and whether it has spread.
   
• Immunotherapy. Immunotherapy helps the immune system recognize and attack cancer cells. It may be considered in some advanced cases.

Clinical trials may also be an option. These studies test new treatments or new ways to use current ones. Ask your care team whether a clinical trial may be right for you.

Causes & Risk Factors

The exact cause of UPS is usually not known. It begins when cells in the connective tissue develop changes in their DNA that cause them to grow out of control.

Some soft tissue sarcomas have been linked to certain factors, including:

• Prior radiation exposure. Rarely, a sarcoma can develop in an area of the body that received radiation therapy in the past.
  Inherited cancer syndromes. Some genetic conditions passed down in families can raise the risk of developing soft tissue sarcomas.

Having a risk factor does not mean you will develop UPS, and many people with the disease have no known risk factors. Talk with your healthcare provider about your personal risk.

Screening

There is no routine screening test for undifferentiated pleomorphic sarcoma for people at average risk.

Because this cancer is rare, it is most often found when a person or their doctor notices a new or growing lump, or during tests done for another reason. There is no recommended test to look for UPS in people who feel well and have no symptoms.

If you have a lump that does not go away or keeps getting larger, talk with a healthcare provider about whether it should be checked further.

This information is for general education only and is not a substitute for medical advice. Please consult a qualified healthcare provider for diagnosis, treatment recommendations, and guidance based on your personal health history.