What is soft tissue sarcoma?

Soft tissue sarcoma is a disease in which malignant cancer cells form in the soft tissues of the body. Soft tissues include parts of the body that connect, support, and surround other organs, such as muscles, tendons, ligaments, cartilage, fat, blood vessels, lymph vessels, nerves, and tissues surrounding joints [1].

Soft tissue sarcoma can form almost anywhere in the body, including the head, neck, and trunk, but it is most common in the arms, legs, abdomen, and the retroperitoneum area [1]. There are many types of soft tissue sarcoma, and the cells of each type look different under a microscope based on the type of soft tissue where the cancer started [1].

Types of Soft Tissue Sarcoma

Soft tissue sarcomas are classified based on the type of cell from which they originated. Some common types include:

• Angiosarcoma: Forms in blood or lymph vessels [2].
• Liposarcoma: Arises from fat cells, also known as malignant lipoma [2].
• Rhabdomyosarcoma: The most common type in children and adolescents, affecting skeletal muscles [2].
• Fibrosarcoma: Develops in fibrous connective tissues [2].
• Synovial sarcoma: A common type in children and adolescents [2].
• Undifferentiated pleomorphic sarcoma: Often forms in the arms or legs [2].

Causes and Risk Factors

The exact cause of soft tissue sarcoma is not always known, but certain factors may increase the risk of developing it. These factors include:

• Genetic disorders: Such as Li-Fraumeni syndrome, Von Recklinghausen's disease (neurofibromatosis type 1), Gardner syndrome, tuberous sclerosis, and Werner syndrome [1].
• Previous radiation therapy: Exposure to radiation therapy in the past [1].
• Chronic lymphedema: Having lymphedema in the arms or legs for a long period [1].
• Exposure to certain chemicals: Such as thorium dioxide (Thorotrast), vinyl chloride, and arsenic [1].
• HIV and Human Herpesvirus 8 infection: These viruses are associated with Kaposi sarcoma [1].

Symptoms and Signs

Soft tissue sarcoma may initially appear as a painless lump or swelling under the skin, often in an arm or leg [1]. Tumors that start in the abdomen may not cause any symptoms until they grow significantly [1]. As the sarcoma grows and presses on nearby organs, nerves, muscles, or blood vessels, signs and symptoms may include:

• Pain [1].
• Difficulty breathing [1].
• Weakness in the affected area [2].

It is important to note that other conditions may cause these same signs and symptoms. Therefore, if you notice any of these problems, you should see a doctor to determine the cause [1].

Diagnosis and Next Steps

If your doctor suspects you have a soft tissue sarcoma, a biopsy will be performed to confirm the diagnosis [1]. The biopsy method depends on the size and location of the tumor in the body and may include a core needle biopsy or a surgical biopsy [1]. Tissue samples are examined by a pathologist to determine the presence of cancer cells and the grade of the tumor [1]. Due to the difficulty of diagnosing soft tissue sarcoma, it is preferred that samples be examined by a pathologist experienced in diagnosing this type of cancer [1].

After diagnosis, additional tests may be performed to determine the extent of cancer spread (staging), such as X-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI), and positron emission tomography (PET) scans [1]. This information is necessary for planning the appropriate treatment [1]. You can read more about this topic in our comprehensive article on Soft Tissue Sarcoma: Diagnosis, Treatment, and Challenges (Arabic).

Medical references

• Soft Tissue Sarcoma Treatment (PDQ®)–Patient Version
• Childhood Soft Tissue Sarcoma (PDQ®)–Patient Version