- Risk Factors
- Signs & Symptoms
Childhood soft tissue sarcoma is a disease in which malignant (cancer) cells form in soft tissues of the body.
Soft tissues of the body connect, support, and surround other body parts and organs. The soft tissues include the following:
- Tendons (bands of tissue that connect muscles to bones).
- Synovial tissues (tissues around joints).
- Blood vessels.
- Lymph vessels.
Soft tissue sarcoma may be found anywhere in the body. In children, the tumors form most often in the arms, legs, or trunk (chest and abdomen).
There are many different types of soft tissue sarcomas.
The cells of each type of sarcoma look different under a microscope. The soft tissue tumors are grouped based on the type of soft tissue cell where they first formed.
Rhabdomyosarcoma is the most common type of childhood soft tissue sarcoma. It begins in muscles that surround bone. Rhabdomyosarcoma is not discussed in this summary. (See the PDQ summary on Childhood Rhabdomyosarcoma Treatment for more information.) This summary is about the other types of soft tissue sarcoma:
Fibrous (connective) tissue tumors
- Fibromatoses (desmoid tumor).
- Malignant fibrous histiocytoma (also called undifferentiated pleomorphic sarcoma, or spindle cell sarcoma).
Fat tissue tumors
Smooth muscle tumors
Blood and lymph vessel tumors
Peripheral nervous system tumors
- Malignant schwannoma (malignant peripheral nerve sheath tumor).
Bone and cartilage tumors
- Extraosseous osteosarcoma.
- Extraosseous myxoid chondrosarcoma.
- Extraosseous mesenchymal chondrosarcoma.
Tumors with more than one type of tissue
- Malignant mesenchymoma.
- Malignant Triton tumor.
- Malignant ectomesenchymoma.
Tumors of unknown origin (the place where the tumor first formed is not known)
- Alveolar soft part sarcoma.
- Epithelioid sarcoma.
- Clear cell sarcoma (malignant melanoma of soft parts).
- Synovial sarcoma.
- Desmoplastic small round cell tumor.
Besides rhabdomyosarcomas, the most common soft tissue sarcomas in children are in joint tissue, connective tissue, and nerve tissue.
Soft tissue sarcoma occurs in children and adults. Soft tissue sarcoma in children may respond differently to treatment, and may have a better outcome than soft tissue sarcoma in adults. (See the PDQ summary on Adult Soft Tissue Sarcoma Treatment for more information on treatment in adults.)
Having certain diseases and inherited disorders can increase the risk of developing childhood soft tissue sarcoma.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Risk factors for childhood soft tissue sarcoma include having the following inherited disorders:
- Li-Fraumeni syndrome.
- Neurofibromatosis type 1 (NF1).
Other risk factors include the following:
- Having AIDS (acquired immune deficiency syndrome) and Epstein-Barr virus infection.
- Having retinoblastoma in both eyes.
- Past treatment with radiation therapy.
The most common sign of childhood soft tissue sarcoma is a painless lump or swelling in soft tissues of the body.
A sarcoma may appear as a painless lump under the skin, often on an arm, a leg, or the trunk. There may be no other symptoms at first. As the sarcoma grows larger and presses on nearby organs, nerves, muscles, or blood vessels, symptoms may occur, including pain or weakness.
Other conditions may cause the same symptoms that soft tissue sarcomas do. A doctor should be consulted if any of these problems occur.
Diagnostic tests and a biopsy are used to detect (find) and diagnose childhood soft tissue sarcoma.
The following tests and procedures may be used:
- Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
- X-rays: An x-ray is a type of energy beam that can go through the body onto film, making pictures of areas inside the body. A series of x-rays may be done to check the lump or painful area.
- MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).
If these tests show there may be a soft tissue sarcoma, a biopsy is done. One of the following types of biopsies may be used:
- Fine-needle aspiration (FNA) biopsy: The removal of tissue or fluid using a thin needle.
- Core biopsy: The removal of tissue using a wide needle.
- Incisional biopsy: The removal of part of a lump or a sample of tissue.
- Excisional biopsy: The removal of an entire lump of tissue. An excisional biopsy may be used to completely remove smaller tumors that are near the surface of the skin.
Tissue samples will be taken from the primary tumor, lymph nodes, and other areas that may have a tumor. A pathologist views the tissue under a microscope to look for cancer cells and to find out the type and grade of the tumor. The grade of a tumor depends on how abnormal the cancer cells look under a microscope and how quickly the cells are dividing. High-grade tumors usually grow and spread more quickly than low-grade tumors. Because soft tissue sarcoma can be hard to diagnose, patients should ask to have biopsy samples checked by a pathologist who has experience in diagnosing soft tissue sarcoma.
One or more of the following laboratory tests may be done to study the tissue samples:
- Cytogenetic analysis: A laboratory test in which cells in a sample of tissue are viewed under a microscope to look for certain changes in the chromosomes.
- Immunohistochemistry study: A laboratory test in which dyes or enzymes are added to a blood or bone marrow sample to test for certain antigens (proteins that stimulate the body's immune response).
- Immunocytochemistry study: A laboratory test that uses different substances to stain (color) cells in a sample of tissue. This is used to tell the difference between the different types of soft tissue sarcoma.
- Light and electron microscopy: A laboratory test in which cells in a sample of tissue are viewed under regular and high-powered microscopes to look for certain changes in the cells.
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) and treatment options depend on the following:
- The type of soft tissue sarcoma.
- The stage of the cancer (the amount of tumor remaining after surgery to remove it or whether the tumor has spread to other places in the body).
- The location, grade, and size of the tumor and how deep under the skin the tumor is.
- Whether or not the patient also has a condition called neurofibromatosis type 1 (NF1).
- The age of the patient.
- Whether the cancer has just been diagnosed or has recurred (come back).
After childhood soft tissue sarcoma has been diagnosed, tests are done to find out if cancer cells have spread to other parts of the body.
The process used to find out if cancer has spread within the soft tissue or to other parts of the body is called staging. There is no standard staging system for childhood soft tissue sarcoma. Two methods that are commonly used for staging are based on the amount of tumor remaining after surgery to remove the tumor and/or the grade and size of the tumor and whether it has spread to the lymph nodes or other parts of the body. It is important to know the stage in order to plan treatment.
The following tests and procedures may be used in the staging process:
- Sentinel lymph node biopsy may be used to stage childhood soft tissue sarcoma. This is the removal of the sentinel lymph node during surgery. The sentinel lymph node is the first lymph node to receive lymphatic drainage from a tumor. It is the first lymph node the cancer is likely to spread to from the tumor. A radioactive substance and/or blue dye is injected near the tumor. The substance or dye flows through the lymph ducts to the lymph nodes. The first lymph node to receive the substance or dye is removed. A pathologist views the tissue under a microscope to look for cancer cells. If cancer cells are not found, it may not be necessary to remove more lymph nodes.
- CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
The results of the sentinel lymph node biopsy and CT scan are viewed together with the results of the diagnostic tests and initial surgery to determine the stage of the soft tissue sarcoma.
There are three ways that cancer spreads in the body.
The three ways that cancer spreads in the body are:
- Through tissue. Cancer invades the surrounding normal tissue.
- Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
- Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.
When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if breast cancer spreads to the bones, the cancer cells in the bones are actually breast cancer cells. The disease is metastatic breast cancer, not bone cancer.
One method used to stage childhood soft tissue sarcoma is based on how much cancer remains after surgery to remove the tumor and whether the cancer has spread:Nonmetastatic childhood soft tissue sarcoma
In nonmetastatic childhood soft tissue sarcoma, the cancer has been partly or completely removed by surgery and has not spread to other parts of the body.
- Group I: The tumor has been completely removed by surgery.
- Group II: After surgery to remove the tumor, there are remaining cancer cells that can be seen only with a microscope.
- Group III: After surgery, there is tumor remaining that can be seen with the eye.
Metastatic childhood soft tissue sarcoma
- Group IV: The cancer has spread from where it started to other parts of the body (metastasis).
Another method used to stage childhood soft tissue sarcoma is based on the size of the tumor and whether cancer has spread to lymph nodes or other parts of the body.
This staging system is based on the following:
- The size of the tumor.
- Whether the tumor has spread to the lymph nodes.
- Whether the tumor has spread to other parts of the body.
Recurrent and Progressive Childhood Soft Tissue Sarcoma
Recurrent childhood soft tissue sarcoma is cancer that has recurred (come back) after it has been treated. The cancer may come back in the same place or in other parts of the body. Progressive childhood soft tissue sarcoma is cancer that did not respond to treatment.