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General Information about Childhood Soft Tissue Sarcoma


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:

  • Muscles.
  • Tendons (bands of tissue that connect muscles to bones).
  • Synovial tissues (tissues around joints).
  • Fat.
  • Blood vessels.
  • Lymph vessels.
  • Nerves.

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. This summary is about the other types of soft tissue sarcoma:

Fibrous (connective) tissue tumors

  • Fibromatoses (desmoid tumor).
  • Dermatofibrosarcoma.
  • Fibrosarcoma.
  • Inflammatory myofibroblastic tumor.

Fibrohistiocytic tumors

  • Malignant fibrous histiocytoma (also called undifferentiated pleomorphic sarcoma, or spindle cell sarcoma).

Fat tissue tumors

  • Liposarcoma.

Smooth muscle tumors

  • Leiomyosarcoma.

Blood and lymph vessel tumors

  • Angiosarcoma.
  • Lymphangiosarcoma.
  • Hemangiopericytoma.
  • Hemangioendothelioma.

Peripheral nervous system tumors

  • Malignant schwannoma (malignant peripheral nerve sheath tumor).

Bone and cartilage tumors

  • Extraosseous osteosarcoma.
  • Extraosseous myxoid chondrosarcoma.
  • 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.

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.

In order to plan the best treatment, a large sample of tissue may be removed during the biopsy to find out the type of soft tissue sarcoma and do laboratory tests. 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).

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Source: National Cancer Institute, www.cancer.gov