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a symptom of clear cell sarcoma is a painless lump under the skin on a leg or foot.

A clear cell sarcoma is an uncommon type of tumor that usually originates in deep soft tissues surrounding the muscles and tendons in the lower legs and feet. Although anyone can develop this malignancy, it is most frequently diagnosed in young adults between ages 20 and 40.

What are the signs of clear cell sarcoma?

The most common symptom of clear cell sarcoma is a painless lump under the skin on a leg or foot, which may be easily misattributed to a sports-related injury. Although it does not hurt, the lump may increase in size over time. Other symptoms can include:

  • Overwhelming fatigue
  • Loss of appetite
  • Unexplained weight loss
  • Night sweats

What causes clear cell sarcoma?

Scientists have established that clear cell sarcoma results from an abnormally fused gene, which occurs when genes from two different chromosomes trade places. Known as reciprocal translocation, the process begins when two chromosomes break apart. Each broken piece carries the genes EWSR1, a protein that plays a role in cellular function, and ATF1, a protein that helps manage cellular growth.

The fused gene forms when the broken chromosome pieces come back together incorrectly. As a result, the reformed chromosomes contain extra genes they should not have. The relocated genes then combine with other genes to create a fused gene known as EWSR1/ATF1.

What are the risk factors for clear cell sarcoma?

Medical researchers do not fully understand what triggers the reciprocal translocation process that leads to the development of clear cell sarcoma, nor have they identified any specific risk factors for this malignancy.

How is clear cell sarcoma diagnosed?

If clear cell sarcoma is suspected, a physician will typically perform a physical exam and order an imaging test, such as a magnetic resonance imaging (MRI) scan, to evaluate the size and location of the tumor. To confirm the diagnosis, the physician will also order a biopsy, which involves taking a small sample of the suspicious lesion for examination under a microscope by a pathologist, who can identify cancerous cells. Among the different types of biopsies, the preferred methods for diagnosing clear cell sarcoma are:

  • Open biopsy – A surgical incision is made to remove the tissue sample.
  • Core needle biopsy – A large needle is used to obtain the tissue sample.

While a fine needle aspiration can help a physician identify cancerous cells, the sample size is usually insufficient for the physician to conclusively characterize the cancer as clear cell sarcoma.

What are the treatment options for clear cell sarcoma?

Treatment for clear cell sarcoma usually involves surgery. For instance, a surgeon may perform a wide local excision to remove as much of the tumor as possible along with a slim margin of healthy tissue. Radiation therapy may be administered before surgery to help shrink the tumor and make it easier to remove, or after surgery to help destroy any residual cancer cells and prevent a recurrence.

Because clear cell sarcoma often comes back, most patients are continually monitored for new tumors after completing treatment. This may include a follow-up appointment with a physician every three months for the first two years.

Sarcoma treatment at Moffitt Cancer Center

Because clear cell sarcoma is relatively rare and can be challenging to treat, it is important to seek treatment at a high-volume cancer center. The multispecialty team in Moffitt’s renowned Sarcoma Program has the highly specialized expertise necessary to treat all types of sarcomas, including clear cell sarcoma. Our outstanding research team continues to investigate promising new treatment options for clear cell sarcoma in clinical trials, such as targeted therapies designed to block overactive signaling molecules in cancer cells that promote cancer growth. We know that each patient is unique, and we are here for everyone. Nothing is standard at Moffitt.

If you would like to learn more about clear cell sarcoma, contact Moffitt Cancer Center at 1-888-663-3488 or complete our new patient registration form online. You do not need a referral to request an appointment with a specialist at Moffitt, where we have an unparalleled understanding of the science and a deep appreciation of your needs.


The Liddy Shriver Sarcoma Initiative – What Is Clear Cell Sarcoma?