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epithelioid sarcoma begins as a single lump that is small, firm and painless

Epithelioid sarcoma is a relatively rare type of soft tissue tumor. Oftentimes, the cancer originates in soft tissues under the skin of a finger, hand, forearm, lower leg or foot, although it can potentially develop anywhere in the body.

Distal epithelioid sarcoma (the conventional form) primarily occurs in teenagers and young adults. Proximal, or large-cell, epithelioid sarcoma is less common, more aggressive and mainly affects adults 40 and older.

What are the signs of epithelioid sarcoma?

In many cases, epithelioid sarcoma begins as a single lump that is small, firm and painless. Sometimes, the tumor looks like a poorly healing wound that can be easily misidentified as a skin infection. Over time, multiple growths may form.

In some cases, epithelioid sarcoma causes contracture, which is a tightening of the surrounding muscles, tendons, skin and other soft tissues. This can lead to joint stiffness and weakness.

What causes epithelioid sarcoma?

The causes of epithelioid sarcoma are not well understood. Researchers have linked the malignancy to a gene mutation that effectively “switches off” the SMARCB1/INI1 protein, which is known to be a potent tumor suppressor. As such, the gene mutation allows cancer to develop and progress.

How is epithelioid sarcoma diagnosed?

If epithelioid sarcoma is suspected, a physician will typically perform a physical exam and order blood work and imaging tests. Magnetic resonance imaging (MRI) is usually the preferred imaging modality due to the high level of detail it provides, although other imaging tests such as computed tomography (CT) and positron emission tomography (PET) may be used as well. Imaging plays an important role in diagnosing epithelioid sarcoma because it can provide vital information about the exact location, size and spread of the tumor.

A needle or surgical biopsy is necessary to confirm a diagnosis of epithelioid sarcoma. The physician will remove a small sample of tumor tissue for examination under a microscope by a pathologist, who can identify cancerous cells and the SMARCB1/INI1 marker.

What are the treatment options for epithelioid sarcoma?

Epithelioid sarcoma may be treated with:

  • Surgery – A surgeon removes as much of the tumor as possible along with a slim margin of surrounding healthy tissue. A limb-sparing approach is generally used whenever feasible.
  • Radiation therapy – High-energy beams, such as X-rays or protons, are aimed directly at the tumor to destroy cancerous cells. Radiation therapy may be administered before surgery to shrink the tumor and make it easier to remove, or after surgery to target residual cancer cells and help reduce the risk of a recurrence.
  • Chemotherapy – After entering the bloodstream, powerful medications circulate throughout the body to target and destroy widespread cancer cells. Chemotherapy can be effective for treating epithelioid sarcoma along with surgery or as a standalone treatment if the cancer has spread.

Sarcoma treatment at Moffitt Cancer Center

Epithelioid sarcoma is an uncommon malignancy that tends to have a high rate of recurrence and can potentially spread to other areas of the body. Therefore, it is best to seek care at a comprehensive cancer center with a multispecialty team that sees many patients with all types of sarcomas to ensure a proper diagnosis and treatment.

Moffitt Cancer Center has been designated a Comprehensive Cancer Center by the National Cancer Institute, which is a testament to our dedication to advancing cancer care for all current and future patients. Our outstanding research team continues to investigate promising new treatment options for epithelioid sarcoma in clinical trials, such as therapies that specifically target the SMARCB1/INI1 gene mutation.

At Moffitt, we know you don’t want "textbook" treatment—you want treatment that is specific to you. We are dedicated to moving beyond standard treatments because, when it comes to our patients, nothing is standard.

If you would like to learn more about epithelioid 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 in our Sarcoma Program.


The Liddy Shriver Sarcoma Initiative – Epithelioid Sarcoma
National Library of Medicine – Oncogenic roles of SMARCB1/INI1