Soft tissue sarcoma (STS) is a type of cancerous tumor that can grow in the body’s soft tissues. If it occurs in the thigh, it may feel like a person has a lump in their thigh, though symptoms may not be present at first.

STS occurs in soft tissues such as the blood vessels, muscles, nerves, and fat.

This article looks at types of STS that can occur in the thigh, as well as the symptoms, diagnosis, and more.

A person with soft tissue sarcoma in the thigh. -1Share on Pinterest
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STS can occur in the thigh.

Although STS can occur in any part of the body, most STS tumors start in the limbs, and 45% develop in the lower limbs.

In addition to the legs, STS can occur in the:

  • arms
  • belly
  • internal organs
  • trunk
  • neck
  • head

Some types of STS occur more often in particular body areas.

Learn more

Learn more about STS in other areas.

The types of sarcomas that most often develop in the thigh are as follows:

  • Fibromyxoid sarcoma or Evan’s tumor: These types of STS are usually painless and slow-growing and typically occur in the legs, arms, or trunk. They are relatively rare and account for 0.6% of all STS cases.
  • Liposarcomas: These are cancerous growths of fat tissue that usually develop in the thigh, in the belly, or behind the knee. Fewer than 20% of all cases of STS in the United States are liposarcomas.
  • Solitary fibrous tumors: These tumors usually do not spread to other tissues or structures, and they may be either benign or malignant. They usually occur in the thigh, pelvis, or underarm or in the lining around the lung (the pleura). They are rare, occurring in fewer than 2% of all STS cases.

People typically do not experience any symptoms during the early stages of STS.

Because STS can occur deep within flexible tissue, tumors may grow for some time, moving and stretching healthy tissue out of the way, before a person notices any symptoms.

A common symptom of STS in a limb, such as the thigh, is an area of swelling or a lump.

The lump may be painless, or it may be painful if it has begun to press against nerves or muscles.

The lump from a sarcoma is usually difficult to move around, unlike a common type of lump called a lipoma.

A lipoma is an often harmless overgrowth of fat cells, which a person can usually move around easily by pushing against it.

If a person notices any unfamiliar lumps on their body, they should consult a doctor to rule out more serious causes.

To diagnose STS in the thigh, a doctor will usually begin with a physical examination and ask questions about a person’s symptoms and medical history.

The doctor will usually follow with a series of imaging tests and a biopsy to determine whether the lump is cancerous.

Imaging tests can also tell a doctor whether STS has spread to lymph nodes or other areas.

Imaging tests may include:

Once a doctor has assessed the results of a person’s imaging tests, they may perform a biopsy.

This involves extracting a small sample of tissue from the tumor. A healthcare professional then analyzes the sample under a microscope.

This procedure can help healthcare professionals determine whether the cells are cancerous and, if so, whether they are from a sarcoma or another type of cancer.

The outlook for any STS depends on various factors, including the type and stage of the cancer.

A 5-year relative survival rate predicts how likely those with the same stage and type of STS are to live for 5 years after diagnosis compared with people in the overall population.

The survival rates for specific stages of STS are as follows:

SEER stage Stage description 5-year relative survival rate
localizedSTS is limited to the area where it first developed and has not spread to other tissues. 81%
regionalSTS has spread to nearby lymph nodes or structures.56%
distantSTS has spread to other organs or structures. 15%
combinedThis is the average of all SEER stages combined.65%

However, these rates give only a rough idea of the outlook for STS. To get a better idea of their specific outlook, a person should consult a doctor.

Learn more about the outlook for soft tissue sarcoma.

This section answers some frequently asked questions about STS in the thigh.

What is sarcoma of the thigh?

A sarcoma of the thigh is a type of cancerous tumor that develops in the soft tissue of the thigh.

Common types include fibromyxoid sarcomas, liposarcomas, and solitary fibrous tumors.

What does sarcoma in the thigh feel like?

A lump from STS in the thigh may be painful if the mass is pressing against nerves or muscles, or it may be painless.

A person generally cannot move the lump around easily by pressing against it.

Is sarcoma on the thigh curable?

If the STS is low grade and has not spread or if a doctor diagnoses it early, a cure may be possible.

If the tumor is large or high grade, it has a greater chance of spreading or recurring.

STS most often occurs in the legs, although a person may develop STS in other areas, such as the arms, trunk, internal organs, or neck.

Types of STS that most often occur in the thigh include fibromyxoid sarcomas, liposarcomas, and solitary fibrous tumors.

The most common symptom of STS in the thigh is a lump, which may be either painful or painless.