Sarcomas, Soft Tissue: Diagnosis

Approved by the Cancer.Net Editorial Board, 11/2023

ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of a medical problem. Use the menu to see other pages.

Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If cancer has spread, it is called metastasis. Doctors may also do tests to learn which treatments may work best.

For most types of cancer, a biopsy is the only sure way for the doctor to know if an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Although biopsies have a small chance of not giving a definite answer, they are very important to allow your doctor to make a clear diagnosis and develop a team-based treatment plan.

How sarcoma is diagnosed

There are different tests used for diagnosing sarcoma. Not all tests described here will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:

  • The type of cancer suspected

  • Your signs and symptoms

  • Your age and general health

  • The results of earlier medical tests

There are no standard screening tests for sarcoma. A doctor should examine any unusual or new lumps or bumps that are growing or, in adults, are larger than 2 inches (5 centimeters; or smaller in young children) to make sure it is not cancer. If a sarcoma is suspected, it is very important to talk with a doctor who has experience with this type of cancer.

A diagnosis of sarcoma is made by a combination of clinical examination by a doctor and imaging tests. It is confirmed by the results of a biopsy. In addition to a physical examination, some of the tests described below may be used to diagnose sarcoma.

Imaging tests

Imaging tests show pictures of the inside of the body. Both benign and cancerous tumors can show up on imaging tests, such as an x-ray. A radiologist, a medical doctor who performs and interprets imaging tests to diagnose disease, will use the way the tumor looks on the test to help determine whether it may be benign or cancerous. However, a biopsy is almost always needed.

  • X-ray. An x-ray creates a picture of the structures inside of the body using a small amount of radiation. X-rays are particularly useful for bone sarcomas but less valuable for soft-tissue sarcomas.

  • Ultrasound. An ultrasound creates a picture of the structures inside the body using sound waves. It may be used to look at lumps under the skin or other organs in the body. A vaginal ultrasound may be used to diagnose sarcoma of the uterus.

  • Computed tomography (CT or CAT) scan. A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. A CT scan can be used to measure the tumor’s size or see if the cancer has spread somewhere else. Sometimes, a special dye called contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a patient’s vein and/or be a pill or liquid the patient must drink.

  • Magnetic resonance imaging (MRI). An MRI produces detailed images of the inside of the body using magnetic fields, not x-rays. MRI can be used to measure the tumor’s size. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye can be injected into a patient’s vein. MRI is often used to determine whether a sarcoma can be removed with surgery.

  • Positron emission tomography (PET) or PET-CT scan. A PET scan creates pictures of organs and tissues inside the body. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A small amount of a radioactive sugar substance is injected into the patient’s body. This sugar substance is taken up by cells that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. However, the amount of radiation in the substance is too low to be harmful. A scanner then detects this substance to produce images of the inside of the body. This technique can be used to look at both the tumor’s structure and how much energy is used by the tumor and normal tissues. This information can be helpful in planning treatment and evaluating how well treatment is working, but it is usually not performed in all cases of known or suspected soft-tissue sarcoma.

Tests for sarcomas in specific organs

  • Mammography. A mammogram is a type of x-ray that looks for any abnormalities or tumors in the breast. This imaging test may be used with MRI scans, CT scans, and a biopsy to diagnose a sarcoma of the breast.

  • Bone scan. A bone scan looks at the inside of the bones using a radioactive tracer. The amount of radiation in the tracer is too low to be harmful. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears lighter to the camera, and areas of injury, such as those caused by cancer, stand out on the image.

  • Heart evaluation. A heart evaluation, including an electrocardiogram (EKG or ECG) and an echocardiogram (ECHO), will look for structural abnormalities in the organ and motion of the walls of the heart. This evaluation is used to diagnose cardiac sarcoma.

Biopsy and tissue tests

Imaging tests may suggest the diagnosis of sarcoma, but a biopsy will be needed to confirm the diagnosis and to find out the type of sarcoma. Because a biopsy that is not properly done can make a surgery more difficult, whenever a sarcoma is suspected, it is very important for a patient to see a sarcoma specialist before any surgery or biopsy is done.


A biopsy is the only way to make a reliable diagnosis, even if other tests can suggest that cancer is present. During biopsy, a small amount of tissue is removed for examination under a microscope. A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.

Because soft-tissue sarcomas are rare, an expert pathologist should review the tissue sample to properly diagnose a sarcoma. Sometimes properly diagnosing a sarcoma requires special tests on the tumor tissue, and it is best if a specialist who sees this type of cancer regularly does this.

There are different types of biopsies.

  • For a needle biopsy, a doctor removes a small sample of tissue from the tumor with a needle-like instrument—usually a core needle biopsy. This may be performed with the help of ultrasound, CT scan, or MRI to precisely guide the needle into the tumor.

  • In an incisional biopsy, a surgeon cuts into the tumor and removes a sample of tissue.

  • In an excisional biopsy, the surgeon removes the entire tumor. Excisional biopsies are generally not recommended for sarcomas because the risk of local recurrence is very high and second surgeries are often needed to completely remove the tumor. A recurrence is when cancer comes back after treatment.

If a biopsy is not optimally performed, it can make surgery more difficult. That is one of the many reasons why a patient should be seen in a sarcoma specialty center before the biopsy is performed, so that the treating surgeon can identify the location for the biopsy. It is also very important to have an expert pathologist review the sample of tissue to appropriately diagnose a sarcoma.

Tissue testing of the tumor

Your doctor or the pathologist looking at the sarcoma may recommend running laboratory tests on a tumor sample to identify specific genes, proteins, and other factors unique to the tumor. Results of these tests will help decide what the treatment should be, because each sarcoma can be as different from one another as breast cancer is different from colon cancer.

After diagnostic tests are done, your doctor will review the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer. This is called staging and grading.

The next section in this guide is Stages and Grades. It explains the system doctors use to describe the extent of the disease. Use the menu to choose a different section to read in this guide.