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Previously referred to as “malignant fibrous histiocytoma,” undifferentiated pleomorphic sarcoma is a subtype of sarcoma, a cancer affecting the body’s connective tissues (e.g., bones, cartilage, muscles, tendons, ligaments, fat, skin, nerves and blood vessels). Different sarcoma subtypes affect different areas of the body, and undifferentiated pleomorphic sarcoma typically develops in the soft tissues of the arms, legs and area behind the abdominal organs (the retroperitoneum). Below, we explore undifferentiated pleomorphic sarcoma causes, risk factors, symptoms, diagnosis and treatment options.

What causes undifferentiated pleomorphic sarcoma?

Researchers are still working to determine exactly what causes undifferentiated pleomorphic sarcoma. However, studies suggest that people over the age of 50 and those who previously received radiation therapy near the area in question tend to have a higher risk of developing the malignancy. With that being said, it’s possible to develop this cancer without having any known risk factors, and it’s also possible to have multiple risk factors and never experience the disease.

What are the symptoms of undifferentiated pleomorphic sarcoma?

Undifferentiated pleomorphic sarcoma can cause the following symptoms:

  • Swelling
  • A lump that increases in size
  • Pain
  • Numbness
  • Tingling
  • Fever
  • Unintended weight loss

Other symptoms will depend on where the cancer is located within the body. For example, if the malignancy develops within the abdomen, someone may experience reduced appetite and constipation. Undifferentiated pleomorphic sarcoma is generally considered to be an aggressive type of cancer, and it’s fairly common for it to spread (metastasize) to other areas of the body, including the lungs and lymph nodes.

How is undifferentiated pleomorphic sarcoma diagnosed?

If a physician suspects that a patient has undifferentiated pleomorphic sarcoma, they’ll typically ask about the patient’s medical history and any symptoms they’re experiencing, then perform a thorough physical examination. They may also order one or more imaging tests—for example, a computed tomography (CT) scan, a magnetic resonance imaging (MRI) scan, a positron emission tomography (PET) scan or an X-ray—as well as a biopsy (a tissue sample).

How is undifferentiated pleomorphic sarcoma treated?

Treatment for undifferentiated pleomorphic sarcoma will vary from one patient to another based on factors including the cancer’s size and where it’s located within the body. With that being said, treatment often involves one or more of the following:

  • Chemotherapy
  • Immunotherapy
  • Radiation therapy
  • Surgery to remove the cancerous cells
  • Targeted drug therapy

In many cases, undifferentiated pleomorphic sarcoma returns after treatment has been completed, so it’s important that patients continue monitoring their condition and attend any follow-up appointments with their physician.

Undifferentiated pleomorphic sarcoma diagnosis and treatment at Moffitt

As is generally the case with other types of cancer, early detection and treatment provide undifferentiated pleomorphic sarcoma patients with the best possible prognosis and quality of life. So, if you’re experiencing any of the symptoms listed above, it’s important that you consult with a specialist as soon as possible.

Fortunately, you can turn to Moffitt Cancer Center—the only National Cancer Institute-designated Comprehensive Cancer Center based in Florida—for undifferentiated pleomorphic sarcoma diagnosis and treatment. Our Sarcoma Program’s multispecialty team of experts work together to provide patients with highly individualized treatment plans, helping to ensure the best possible results.

Contact Moffitt Cancer Center today to request an appointment—you can call us at 1-888-663-3488 or fill out our new patient registration form online, and no referral is needed. We understand how important it is to promptly diagnose and treat undifferentiated pleomorphic sarcoma and other malignancies, and you can rest easy knowing that we’ll connect you to one of our cancer experts as soon as possible.


Radiopaedia: Undifferentiated Pleomorphic Sarcoma
The Liddy Shriver Sarcoma Initiative: Malignant Fibrous Histiocytoma (Undifferentiated Pleomorphic Sarcoma)