Epithelioid Sarcoma: Symptoms, Causes, and Treatment

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026

Healthy soft tissue compared with epithelioid sarcoma, where a firm nodule of cancer cells grows under the skin and can spread to lymph nodes and other body parts.

Quick answer

Epithelioid sarcoma is a rare soft tissue sarcoma, a cancer that begins in the body's connective tissues, usually under the skin. The first sign is usually a small, firm, painless lump, most often on the hands, fingers or forearms. Surgery to remove the tumor plus a margin of healthy tissue is the most common treatment.

What the research says

According to PubMed:

• Stage at diagnosis matters most, and surgery is linked to better survival. In a SEER registry analysis of 1,123 patients, disease was localized in 45.3%, regional in 26.5%, and distant in 28.2%; median overall survival was 84 months and 5-year cancer-specific survival was 53.7%. Distant stage raised risk (adjusted HR 5.379) while surgery lowered it (adjusted HR 0.397, 95% CI 0.280 to 0.563). (Obeidat, DOI).

• Clear surgical margins and small tumors predict a better outlook. In 36 patients who all had surgery, local recurrence rates were 32.0% at 2 years and 45.1% at 5 years, 5-year overall survival was 43.3%, and a clear (R0) margin was the only factor tied to lower local recurrence and distant spread; tumors over 5 cm did worse. (Zhang et al., DOI).

• Chemotherapy helps only modestly, so trials matter. In 22 patients given chemotherapy, median progression-free survival with first-line treatment was 6.4 months (9.7 months with anthracycline-based regimens), and the authors concluded that poor responses underscore the need for targeted therapies and that clinical trials should be offered. (Czarnecka et al., DOI).

Study details are from PubMed abstracts.

Key facts at a glance

Question	Answer
What type of cancer is it?	A soft tissue sarcoma (cancer of the body's connective tissues) [1]
Where does it usually start?	Under the skin, most often the finger, hand, forearm, knee, or lower leg [1]
Who does it affect most?	Teenagers and young to middle-aged adults [1]
How does it grow?	Slowly, and it can come back after treatment [1]
What does it feel like?	A small, firm nodule that is usually not painful or tender [1]
Is it preventable?	The cause is not known, and there is no known way to prevent it [1]

What is epithelioid sarcoma?

Epithelioid sarcoma is a rare type of cancer that starts as a growth of cells in the soft tissue, the tissues that support, surround, and connect other parts of the body, such as muscle, fat, and connective tissue fibers.

It can happen anywhere on the body, but it most often starts just under the skin on the finger, hand, or forearm, or on the knee or lower leg. It can occur at any age, yet it most often affects teenagers and young to middle-aged adults. [1]

One important thing to know: epithelioid sarcoma tends to grow slowly. It can also come back after treatment, which is called a recurrence. Because it is one of many types of soft tissue sarcoma, and because most of those types are themselves not common, experts recommend seeking care at a cancer center that has experience treating sarcoma. [1]

Symptoms: the small lump most people ignore

The earliest sign is usually easy to overlook. The cancer typically begins as a small, firm growth under the skin called a nodule, and this lump is usually not painful or tender. [1]

Sometimes more than one nodule appears. In some cases, the nodule eventually forms a sore on the skin that will not heal, a detail that often leads people to mistake it for an ordinary skin infection. [2]

What to notice: a small firm nodule under the skin that is usually painless. Report any persistent lump to your doctor.

The table below summarizes what to look for and where.

What you may notice	Where it usually appears
A small, firm lump under the skin	Finger, hand, or forearm (most common)
Sometimes more than one lump	Knee or lower leg (also possible)
The lump is usually not painful	Anywhere on the body (less common sites)
Sometimes a sore on the skin that will not heal	At the site of the original nodule

Because the lump rarely hurts, people often live with it for months. That is part of why this cancer is frequently diagnosed late, and it is a strong reason to have any persistent lump checked.

Causes: what goes wrong in the cells

The exact cause of epithelioid sarcoma is not known. What is known is how it starts at the cellular level. [1]

It begins when cells in the soft tissue get changes in their DNA. DNA is the instruction manual inside every cell. In healthy cells, the instructions say to grow and multiply at a set rate and to die at a set time. In cancer, the DNA changes give different instructions: grow and multiply quickly, and keep living when healthy cells would normally die. The result is too many cells, which can form a growth that can be felt through the skin.

Cancer cells can also break away from the original growth and spread. Epithelioid sarcoma can spread to the lymph nodes and to other parts of the body. When that happens, it is called metastatic cancer.

Who is at higher risk?

The risk is higher in younger people. Most cases occur in adolescents and young to middle-aged adults, and the condition is less common in children and in older adults. There is no known way to prevent epithelioid sarcoma. Because the cause is unknown, no specific behaviors, foods, or exposures have been linked to it.

Why epithelioid sarcoma is hard to diagnose

This cancer is notoriously difficult to diagnose, and that difficulty is itself worth understanding. The lump looks like much more common, harmless problems. A sore that will not heal is easily mistaken for a routine skin infection, and a painless bump is easily written off as a cyst. [2]

That misidentification matters: every week that passes before the correct diagnosis is one more week the cancer can grow. Any lump under the skin that is firm, persistent, or growing deserves a professional look.

How epithelioid sarcoma is diagnosed

Diagnosis combines imaging with a tissue test. The steps work together to show exactly where the tumor is, how large it is, and whether it is truly cancer. [2]

Imaging tests. An X-ray, MRI, CT scan, or PET scan can show the location and size of the growth. Each test offers different detail: MRI is particularly good at showing soft tissue, while a PET scan highlights areas of high cell activity.

Biopsy. A biopsy removes a sample of the tissue, either with a needle passed through the skin into the growth or with a small surgical procedure. The sample is tested in a laboratory to determine whether it is cancer. Special tests on the tissue give the team more details about the exact type, and the care team uses all of this information to build a treatment plan.

Finding it and treating it: imaging and biopsy for diagnosis, then surgery, radiation, targeted therapy, chemotherapy, or clinical trials.

Treatment: surgery first, support when needed

Surgery is the most common treatment for epithelioid sarcoma, and sometimes other treatments are used in addition to it. [2]

Treatment	How it works	When it is used
Surgery	The cancer is removed along with some healthy tissue around it, to make sure all cancer cells are gone	The most common approach; lowers the risk of the cancer returning
Radiation therapy	Powerful energy beams kill cancer cells	Before surgery to shrink the tumor, or after surgery to kill leftover cells
Targeted therapy	Medicines attack specific chemicals in the cancer cells that help them grow; blocking those chemicals causes the cells to die	If surgery is not possible, or other treatments do not work
Chemotherapy	Strong medicines that kill cancer cells throughout the body	When the sarcoma has spread, or when surgery is not an option
Clinical trials	Studies testing new treatments	A chance to try the latest options; side effects may not yet be fully known

The surgical approach deserves emphasis. Removing the tumor plus a margin of healthy surrounding tissue makes complete removal more likely, and that directly lowers the risk of the cancer coming back.

Before surgery, radiation can shrink the tumor so complete removal is more achievable. After surgery, radiation can kill cells left behind. Targeted therapy and chemotherapy are reserved for situations where surgery cannot do the whole job, such as when the cancer has spread or cannot be safely removed.

If you are offered a clinical trial, ask your team about eligibility. New treatments are being studied for this rare cancer, and trials can offer access to options that are not yet widely available.

Preparing for your appointment

When worrying symptoms prompt an appointment, you will often be referred to an oncologist, a doctor who specializes in cancer. A few practical steps help you make the most of the visit.

Before the appointment, ask whether you need to prepare, such as fasting for certain tests. Write down your symptoms, key personal information (major life changes and family cancer history), and every medication, vitamin, and supplement you take, with doses. Bring a list of questions.

Useful questions to ask include: Do I have cancer? Do I need more tests? What are my treatment options? What are the risks? Can any treatment cure the cancer? May I have a copy of the pathology report? How much time do I have to consider my options? And what happens if I choose not to treat?

Expect your doctor to ask about when symptoms began, whether they are constant or occasional, how severe they are, and what improves or worsens them.

Conclusion and next steps

Epithelioid sarcoma is rare, slow-growing, and usually painless, which is exactly what makes it dangerous when ignored. It hides as a small firm lump on the hands and arms of young people, mimicking the harmless bumps and stubborn sores of everyday life.

The good news is that it can be treated. Surgery to remove the tumor with a margin of healthy tissue is effective, and radiation, targeted therapy, chemotherapy, and clinical trials broaden the options when surgery alone is not enough. The single most powerful action you can take is to have any persistent, firm lump under the skin evaluated, especially if it is not painful.

Next steps: If you have a lump that has not gone away, or a skin sore that will not heal, schedule an evaluation with a health care provider.

Frequently asked questions

What does epithelioid sarcoma feel like?

Epithelioid sarcoma usually feels like a small, firm lump under the skin that is not painful or tender. It most often appears on the finger, hand, or forearm, and sometimes on the knee or lower leg. [1]

Why is epithelioid sarcoma hard to diagnose?

Epithelioid sarcoma looks like much more common problems. The painless lump can be mistaken for a harmless cyst, and the sore that will not heal is often confused with an ordinary skin infection, so the correct diagnosis is frequently delayed. [2]

Can epithelioid sarcoma be cured?

Treatment can remove the cancer, and surgery lowers the chance of it returning. However, the cancer can come back after treatment, and it can spread to lymph nodes and other body parts, which is why expert care at a sarcoma-experienced cancer center matters. [1][2]

What are the treatment options?

Surgery to remove the tumor plus surrounding healthy tissue is the most common treatment. Radiation therapy, targeted therapy, and chemotherapy are used depending on the tumor's size, location, and whether it has spread. Clinical trials may also be an option. [2]

Who is most likely to get epithelioid sarcoma?

Epithelioid sarcoma most often affects teenagers and young to middle-aged adults, and it is less common in children and older adults. The cause is unknown and there is no known way to prevent it. [1]

This article is for general education and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional about your individual situation.

References

1. Mayo Clinic Staff. Epithelioid sarcoma: Symptoms and causes. Mayo Clinic. March 24, 2026. https://www.mayoclinic.org/diseases-conditions/epithelioid-sarcoma/symptoms-causes/syc-20577574

2. Mayo Clinic Staff. Epithelioid sarcoma: Diagnosis and treatment. Mayo Clinic. March 24, 2026. https://www.mayoclinic.org/diseases-conditions/epithelioid-sarcoma/diagnosis-treatment/drc-20577575

3. Obeidat A. Prognostic determinants and survival outcomes in epithelioid sarcoma: A contemporary population-based analysis of 1123 patients. Medicine (Baltimore). 2026;105(8):e47651. PMID 41731748. https://doi.org/10.1097/MD.0000000000047651

4. Zhang S, Jing C, Liu H, et al. Epithelioid sarcoma: A single-institutional retrospective cohort study of 36 cases. J Orthop Surg (Hong Kong). 2021;29(3):23094990211029349. PMID 34405755. https://doi.org/10.1177/23094990211029349

5. Czarnecka AM, Chmiel P, Błoński P, et al. Long-term outcomes of sequential chemotherapy in epithelioid sarcoma. J Chemother. 2024;37(5):436-447. PMID 39115147. https://doi.org/10.1080/1120009X.2024.2385261