An ultrasound is one of several tests that can help confirm a soft tissue sarcoma diagnosis. Ultrasounds create detailed images showing the size and location of tumors. These images can also be used to plan treatment.

A soft tissue sarcoma is a cancerous tumor that can grow on soft connective tissues in your body, including muscles, nerves, blood vessels, and the lining of your joints.

An ultrasound is one of several tests that healthcare professionals might use to confirm a diagnosis of soft tissue sarcoma. This type of imaging uses high frequency sound waves to create detailed images of tumors growing on soft tissues.

This article takes a closer look at how soft tissue sarcomas may appear on an ultrasound and which other tests doctors might use to confirm a diagnosis.

An ultrasound creates images using sound waves. There are a few ways it can help doctors diagnose soft tissue sarcoma. For instance, it can help them see tumors on soft tissues and assess their size, location, and shape.

Doctors can use the information on an ultrasound to help diagnose and stage a soft tissue sarcoma.

Ultrasounds are typically chosen for their accuracy. Sarcoma tumors create more distinctive images on ultrasounds than on X-rays. Ultrasounds can detect soft tissue sarcoma tumors 80–90% of the time.

The following qualities of soft tissue sarcoma tumors can often be seen on ultrasound scans:

  • many visible blood vessels
  • a size larger than 46 millimeters (1.18 inches)
  • a location deep in a tissue
  • an oval, round, or double-lobed shape
  • uneven margins

But not all soft tissue sarcomas have these qualities. Healthcare professionals may use additional testing for suspected soft tissue sarcoma tumors that don’t show these characteristics on an ultrasound.

Ultrasounds are also sometimes used during a procedure called an ultrasound-guided needle biopsy.

During this procedure, doctors will use the ultrasound images to guide a needle into the tumor. They’ll then extract a portion of the tumor so they can test it for cancer cells. This can confirm a diagnosis of soft tissue sarcoma.

Can an ultrasound tell the difference between sarcoma and lipoma?

An ultrasound is often a good tool to help distinguish between a sarcoma and a lipoma. Ultrasounds are sensitive and can create very detailed images. They can typically tell the difference between a sarcoma and a lipoma. However, additional imaging and further testing might be necessary.

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You might undergo several additional tests if your doctor suspects soft tissue sarcoma, such as a physical exam, imaging tests, and a biopsy. The following tests are often part of the diagnostic process:

  • X-ray: An X-ray can be a useful first imaging test to look for tumors and other growths in your body.
  • CT scan: A CT scan creates three-dimensional images of the inside of your body. It can help doctors measure the size of the tumor and assess tumor growth.
  • Magnetic resonance imaging (MRI): MRI scans use magnetic fields to create very detailed images of the inside of your body. Doctors often use them to get an accurate idea of tumor size and to plan treatment.
  • Positron emission tomography (PET) scan: A PET scan is a test that involves taking CT scan images of your body after a healthcare professional has injected a small amount of a special radioactive sugar substance into your body. Cancer cells will absorb this substance and become visible on the CT images.
  • Biopsy: A biopsy involves removing a small portion of the tumor so it can be tested for cancer cells in a lab. The exact type of biopsy you’ll need depends on the location of your soft tissue sarcoma. For instance, some biopsies are done by inserting a needle into the tumor so the sample can be extracted, while others are done by making an incision in your skin to remove all or part of the tumor for testing.
  • Tissue testing: Tissue testing is done in a lab to identify specific genes found in sarcoma cells. It can help doctors plan treatments.

Additional testing can depend on the location of your soft tissue sarcoma.

For example, if your doctor suspects that you have a soft tissue sarcoma in breast tissue, they might order a mammogram. If they suspect a soft tissue sarcoma in a joint, they might order a bone scan.

Your doctor can explain which, if any, of these additional tests you might need.

An ultrasound is one of several tests that healthcare professionals can perform to diagnose a soft tissue sarcoma.

Ultrasounds create very detailed images that can allow doctors to see the location, size, and shape of tumors. This can help them confirm a diagnosis and begin to plan treatment.

You might need additional tests, including further imaging (such as a CT scan, MRI scan, and PET scan), a biopsy, and tissue testing.