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Undifferentiated Embryonal Sarcoma of the Liver (UESL)

Reviewed by: Allison Aguado, MD
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What Is Undifferentiated Embryonal Sarcoma of the Liver (UESL)?

Undifferentiated embryonal sarcoma of the liver (UESL) is a rare kind of liver cancer that happens mostly in children.

What Are the Signs & Symptoms of Undifferentiated Embryonal Sarcoma of the Liver (UESL)?

Many children with UESL have no symptoms. Others may have one or more of these signs: 

  • a lump in the belly, or a bigger belly than usual
  • belly pain
  • a loss of appetite
  • vomiting
  • diarrhea
  • constipation
  • fever
  • tiredness
  • weight loss
  • trouble breathing

What Does "Undifferentiated Embryonal Sarcoma" Mean?

  • "Undifferentiated" means that the cells making up the cancer don't look like any kind of specialized cell, such as a liver cell, muscle cell, or fat cell.
  • "Embryonal" means that the cancer probably grew from cells early in a fetus' development that didn't change (differentiate) into liver cells properly.
  • "Sarcoma" means it's a type of cancer that grows from the kind of cell that forms (cells that connect or support other kinds of tissue in the body).

What Causes Undifferentiated Embryonal Sarcoma of the Liver (UESL)?

Doctors don't know what causes UESL. Most children who get it are 6 to 10 years old. Sometimes older children and adults get UESL.

How Is Undifferentiated Embryonal Sarcoma of the Liver (UESL) Diagnosed?

When a child has symptoms that suggest UESL, the doctor will do an exam and order tests such as:

  • blood tests, including liver and kidney function tests
  • imaging tests:
  • biopsy (removing a small piece of tissue using surgery or a needle with imaging guidance)

Doctors study the biopsy sample to see if the tissue is a . If it is, the biopsy also can show the type of liver tumor. Knowing the tumor type helps them know which treatments are most likely to work well.

How Is Undifferentiated Embryonal Sarcoma of the Liver (UESL) Treated?

Doctors usually use a combination of different treatments for UESL, such as:

Surgery is the most important part of treatment, but many UESL tumors can't be removed easily. A liver transplant may be considered because the whole liver needs to be removed to get the entire tumor out.

Chemotherapy is often used but doesn't always shrink UESL.

Radioembolization (or Y90) is a type of therapy that delivers high-dose radiation directly to the liver tumor through the bloodstream. The radiologist inserts a tiny catheter (plastic tube) in the groin and passes it to the artery closest to the tumor. This procedure protects much of the normal liver tissue from the effects of Y90.

Y90 can be used as primary therapy in liver tumors that don't respond well to chemotherapy. It's also used when the tumors come back or don't shrink enough for surgery.

Transarterial chemoembolization (TACE), which sends chemotherapy particles directly to the tumor.

Tumor ablation, which is when doctors destroy tumors by using small needles to heat or cool them.

Who Treats Undifferentiated Embryonal Sarcoma of the Liver (UESL)?

Undifferentiated embryonal sarcoma of the liver is treated by a health care team, including specialists in:

What Else Should I Know?

UESL tends to grow quickly, but treatment for this cancer is improving. 

If your child has UESL, work with the care team to get the best treatment. This may mean frequent doctor's visits, hospital stays, medical tests, and treatments with side effects.

Talk to the care team about any questions or concerns that you have about the treatment plan. They can help you and your child with the physical and emotional challenges that come with treatment.

After treatment, the doctor will do a checkup every year to see if the cancer has come back and to help take care of any side effects from treatment.

You also can find information and support online at:

Reviewed by: Allison Aguado, MD
Date reviewed: February 2023