Sarcoma

A sarcoma is a type of cancer that begins in the body’s connective tissues, which include bones, muscles, fat, blood vessels, and nerves. These tissues support, protect, and provide structure to other parts of the body. Sarcomas can occur in almost any area but most commonly arise in the arms, legs, and abdomen.

What are the different types of sarcomas?

Sarcomas are broadly divided into two major categories: soft tissue sarcomas and bone sarcomas. There is also a third category called undifferentiated round cell tumours, which includes a small number of rare sarcomas that can develop in either soft tissue or bone.

Soft tissue sarcomas

Soft tissue sarcomas develop in the tissues that connect and support other body parts, such as fat, muscle, nerves, and blood vessels. These tumours are classified based on the type of cell from which they arise, called the cell of origin. The cell of origin is the type that becomes cancerous and gives rise to the tumour. Here are the main subtypes of soft tissue sarcomas:

• Adipocytic tumours: These originate in fat cells. Examples include well differentiated liposarcoma and pleomorphic liposarcoma.
• Fibroblastic and myofibroblastic tumours: These arise from fibroblasts, the cells that produce connective tissue fibres. Examples include myxofibrosarcoma and dermatofibrosarcoma protuberans.
• Vascular tumours: These tumours develop in the cells that make up blood vessels. An example is angiosarcoma.
• Pericytic (perivascular) tumours: These arise from cells that surround blood vessels, such as pericytes. An example is a malignant glomus tumour.
• Smooth muscle tumours: These originate in smooth muscle tissue, such as leiomyosarcoma.
• Skeletal muscle tumours: These develop in skeletal muscle and include embryonal, alveolar, and pleomorphic rhabdomyosarcoma.
• Gastrointestinal stromal tumour (GIST): GIST arises in the digestive tract and is thought to originate from specialized cells in the wall of the gastrointestinal tract.
• Chondro-osseous tumours: These form in cartilage or bone-related tissues within soft tissue. An example is extraskeletal osteosarcoma.
• Peripheral nerve sheath tumours: These tumours develop in the cells that surround nerves. The most common is malignant peripheral nerve sheath tumour (MPNST).
• Tumours of uncertain differentiation: These are sarcomas that do not easily fit into the above categories. Their cell of origin is unclear. Examples include synovial sarcoma, epithelioid sarcoma, and alveolar soft part sarcoma.

Bone sarcomas

Bone sarcomas develop in the bones and are categorized based on the types of tissues or cells they produce. The main subtypes are:

• Osteogenic: These sarcomas produce bone matrix. The most common example is osteosarcoma, which forms new bone tissue.
• Chondrogenic: These sarcomas produce cartilage. Chondrosarcoma is the most common type in this category.
• Vascular: These sarcomas produce blood vessels within the bone. Angiosarcoma of bone is the most common type in this category.
• Other types: Some bone sarcomas produce elements not specific to bone, such as fibrous tissue or other cellular components, but do not fit the above categories. Examples include chordoma and undifferentiated pleomorphic sarcoma of bone.

Is a sarcoma benign or malignant?

A sarcoma is a malignant (cancerous) tumour, meaning it has the potential to grow and spread to other parts of the body. This makes it different from benign (noncancerous) tumours, which remain localized and generally do not pose the same level of danger. Sarcomas can be life-threatening, but many cases can be managed or treated effectively, especially when caught early.

What is the prognosis for a person with sarcoma?

The prognosis for a person with sarcoma depends on various factors, including the type of sarcoma, the size of the tumour, whether it has spread, and how aggressive the cancer is. Treatment options, such as surgery, radiation therapy, and chemotherapy, can improve outcomes. Generally, the earlier the sarcoma is detected, the better the chances for successful treatment. However, each individual’s prognosis is unique and should be discussed with a healthcare provider.

What causes a sarcoma?

The exact cause of most sarcomas is unknown, but several factors may increase the risk of developing one. These include:

• Genetic conditions: Some inherited conditions, such as Li-Fraumeni syndrome or neurofibromatosis, increase the risk of sarcomas.
• Radiation exposure: People who have undergone radiation therapy for other cancers may be at increased risk.
• Chemical exposure: Certain chemicals, like herbicides, have been linked to an increased risk of sarcomas.
• Chronic inflammation: Long-term inflammation can increase the risk of several types of sarcoma.

In most cases, the cause of sarcoma is not known.

What types of tests are used to confirm the diagnosis?

Several tests may be used to diagnose sarcoma, including:

• Imaging tests: X-rays, CT scans, and MRIs can provide detailed images of the tumour, helping doctors assess its size and location.
• Biopsy: A biopsy involves removing a small sample of tissue from the tumour and examining it under a microscope to determine whether it is cancerous. This is the most important test for confirming a sarcoma diagnosis.
• Genetic tests: Some sarcomas have specific genetic mutations that can be tested for, which helps confirm the diagnosis and guide treatment decisions.

Additional tests may be done to check whether the sarcoma has spread to other body parts.

About this article

This article was written by doctors to help you read and understand your pathology report. Contact us if you have questions about this article or your pathology report. For a complete introduction to your pathology report, read this article.

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