General Information About Childhood Soft Tissue Sarcoma
Key Points for This Section
- Childhood soft tissue sarcoma is a disease in which malignant (cancer) cells form in soft tissues of the body.
- There are many different types of soft tissue sarcomas.
- Soft tissue sarcoma occurs in children and adults.
- Having certain diseases and inherited disorders can increase the risk of childhood soft tissue sarcoma.
- The most common sign of childhood soft tissue sarcoma is a painless lump or swelling in soft tissues of the body.
- Diagnostic tests and a biopsy are used to detect (find) and diagnose childhood soft tissue sarcoma.
- Certain factors affect prognosis (chance of recovery) and treatment options.
- A mix of bone and cartilage tissue.
- Fibrous tissue.
- Tendons (bands of tissue that connect muscles to bones).
- Synovial tissues (tissues around joints).
- Blood vessels.
- Lymph vessels.
This summary is about the following types of soft tissue sarcoma:
- Liposarcoma . This is a rare cancer of the fat cells. There are several different types of liposarcoma. Most liposarcomas in children and teenagers are low grade (likely to grow and spread slowly). The most common type is myxoid liposarcoma, which is usually low grade and responds well to treatment. Another type is pleomorphic liposarcoma, which is usually high grade (likely to grow and spread quickly) and is less likely to respond well to treatment.
Bone and cartilage tumors are a mix of bone cells and cartilage cells. Bone and cartilage tumors include the following types:
- Extraskeletal chondrosarcoma . This type of bone and cartilage tumor includes mesenchymal chondrosarcoma, which grows quickly and often spreads to the lungs.
- Extraskeletal osteosarcoma. This type of bone and cartilage tumor is very rare in children and teenagers. It is likely to come back after treatment and may spread to the lungs.
Fibrous (connective) tissue tumors include the following types:
- Desmoid tumor (also called aggressive fibromatosis). This fibrous tissue tumor is low grade (likely to grow slowly). This tumor may come back in nearby tissues but usually does not spread to distant parts of the body. Rarely, the tumor may disappear without treatment.
Desmoid tumors sometimes occur in children with changes in the adenomatous polyposis coli (APC) gene. Changes in this gene cause familial adenomatous polyposis (FAP). FAP is an inherited condition in which many polyps (growths on mucous membranes) form on the inside walls of the colon and rectum. Genetic counseling (a discussion with a trained professional about inherited diseases and a possible need for gene testing) may be needed.
- Fibrosarcoma .
There are two types of fibrosarcoma in children and teenagers:
- Infantile fibrosarcoma (also called congenital fibrosarcoma). This type of fibrosarcoma is found in children aged 4 years and younger. It most often forms in infants and may be seen in a prenatal ultrasound exam. This tumor is often large and fast growing, but rarely spreads to distant parts of the body. The cells of this tumor usually have a certain genetic change called a translocation (part of one chromosome switches places with part of another chromosome). In order to diagnose infantile fibrosarcoma, the tumor cells are checked for this genetic change.
- Adult-type fibrosarcoma. This is the same type of fibrosarcoma found in adults. The cells of this tumor do not have the genetic change found in infantile fibrosarcoma.
- Dermatofibrosarcoma protuberans . This is a rare fibrous tissue tumor found in children and adults. The cells of this tumor have a certain genetic change called a translocation. In order to diagnose dermatofibrosarcoma protuberans, the tumor cells are checked for this genetic change.
- Inflammatory myofibroblastic tumor. This is a fibrous tissue tumor that is likely to come back after treatment but rarely spreads to distant parts of the body. A certain genetic change has been found in about half of these tumors.
- Low-grade fibromyxoid sarcoma. This tumor may come back many years after treatment and is likely to spread to the lungs and the lining of the wall of the chest cavity. Lifelong follow-up is needed.
- Myxofibrosarcoma, low-grade. This is a rare fibrous tissue tumor that is found less often in children than in adults. It is likely to grow slowly.
- Sclerosing epithelioid fibrosarcoma. This is a rare fibrous tissue tumor that usually grows slowly.
Skeletal muscle is attached to bones and helps the body move.
- Rhabdomyosarcoma . Rhabdomyosarcoma is the most common childhood soft tissue sarcoma. See the PDQ summary on Childhood Rhabdomyosarcoma Treatment for more information.
- Leiomyosarcoma . This smooth muscle tumor has been linked with Epstein-Barr virus in children who also have HIV /AIDS. Leiomyosarcoma may also form as a second cancer in survivors of inherited retinoblastoma, even many years after their treatment for retinoblastoma.
So-called fibrohistiocytic tumors include the following types:
- Plexiform fibrohistiocytic tumor . This is a rare tumor that usually affects children and young adults. The tumor usually starts as a painless growth on or just under the skin on the arm, hand, or wrist. It may rarely spread to nearby lymph nodes or to the lungs.
- Undifferentiated pleomorphic sarcoma. This type of tumor may form in parts of the body where patients have received radiation therapy in the past, or as a second cancer in children with retinoblastoma. The tumor is usually found on the arms or legs and may spread to other parts of the body.
- Malignant peripheral nerve sheath tumor . This is a tumor that forms in the protective covering of nerves that are not part of the brain or spinal cord. Some children who have a malignant peripheral nerve sheath tumor have a rare genetic condition called neurofibromatosis type 1 (NF1). This tumor may be low grade or high grade.
Tumors of unknown origin (the place where the tumor first formed is not known) include the following types:
- Alveolar soft part sarcoma . This is a rare tumor of the soft supporting tissue that connects and surrounds the organs and other tissues. It may grow slowly and has often spread to other parts of the body at the time of diagnosis. Alveolar soft part sarcoma may have a better prognosis in children than in adults, when the tumor is 5 centimeters or smaller, or when the tumor is completely removed by surgery.
- Clear cell sarcoma of soft tissue . This is a soft tissue tumor that begins in a tendon (tough, fibrous, cord-like tissue that connects muscle to bone or to another part of the body). Clear cell sarcoma may spread to nearby lymph nodes.
- Desmoplastic small round cell tumor . This tumor most often affects boys and may form and spread in the abdomen, and pelvis or tissues around the testes. Desmoplastic small round cell tumor may also spread to the lungs and other parts of the body.
- Epithelioid sarcoma. This is a rare sarcoma that usually starts deep in soft tissue as a slow growing, firm lump and may spread to the lymph nodes.
- Perivascular epithelioid cell tumors (PEComas). Benign (not cancer) PEComas are commonly found in children with an inherited condition called tuberous sclerosis.
- Extrarenal (extracranial) rhabdoid tumor. This is a rare, fast-growing tumor of soft tissues such as the liver and peritoneum. It usually occurs in young children, including newborns, but it can occur in older children and adults.
- Extraskeletal myxoid chondrosarcoma . This is a rare soft tissue sarcoma that may be found in children and teenagers. This tumor may come back after treatment. Over time, it tends to spread to other parts of the body including the lymph nodes and the lungs.
- Primitive neuroectodermal tumor (PNET)/extraskeletal Ewing tumor. See the PDQ summary on Ewing Sarcoma Treatment for more information.
- Synovial sarcoma . Synovial sarcoma is a common type of soft tissue sarcoma in children and teenagers. Synovial sarcoma usually forms in the tissues around the joints in the arms or legs, but may also form in the trunk, head, or neck. The cells of this tumor usually have a certain genetic change called a translocation (part of one chromosome switches places with part of another chromosome). Larger tumors have a greater risk of spreading to other parts of the body, including the lungs. Children younger than 10 years and those whose tumor is 5 centimeters or smaller have a better prognosis.
Blood vessel tumors include the following types:
- Angiosarcoma (deep). Angiosarcomas may form inside blood vessels or lymph vessels. This type of tumor usually grows quickly.
- Epithelioid hemangioendothelioma. In infants, these tumors often form in the liver but may form in other parts of the body such as the lung. They are usually benign (not cancer). Children with consumptive coagulopathy (also known as Kasabach-Merritt syndrome) may have an increased chance of epithelioid hemangioendothelioma. In children younger than 1 year, the tumor may go away without treatment. A small number of children may develop cancerous tumors over time. Infants with hemangiomas should be checked regularly with ultrasound exams and may be treated with a liver transplant if their tumors are benign. In some cases, the benign tumor may become malignant (cancer) and spread to the lungs, lymph nodes, bones, abdomen, or pelvis.
- Hemangiopericytoma (infantile). This soft tissue tumor has many blood vessels. Children younger than 1 year have a better prognosis. In patients older than 1 year, this tumor is more likely to spread to distant tissues, including the lymph nodes and lungs.
See the following PDQ summaries for information about types of soft tissue sarcoma not included in this summary:
- Childhood Rhabdomyosarcoma Treatment.
- Ewing Sarcoma Treatment.
- Unusual Cancers of Childhood (gastrointestinal stromal tumors).
Soft tissue sarcoma in children may respond differently to treatment, and may have a better prognosis than soft tissue sarcoma in adults. (See the PDQ summary on Adult Soft Tissue Sarcoma Treatment for more information on treatment in adults.)
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. Talk with your child’s doctor if you think your child may be at risk.
Risk factors for childhood soft tissue sarcoma include having the following inherited disorders:
- Li-Fraumeni syndrome.
- Neurofibromatosis type 1 (NF1).
- Familial adenomatous polyposis (FAP).
- Werner syndrome.
- Retinoblastoma gene changes.
Other risk factors include the following:
- Past treatment with radiation therapy.
- Having AIDS (acquired immune deficiency syndrome) and Epstein-Barr virus infection at the same time.
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 and presses on nearby organs, nerves, muscles, or blood vessels, it may cause symptoms, such as pain or weakness.
Other conditions may cause the same symptoms as soft tissue sarcoma. Check with your child’s doctor if you see any of these problems in your child.
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.
- CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, such as the abdomen, 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.
- MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas of the body, such as the chest, abdomen, arms, or legs. This procedure is also called nuclear magnetic resonance imaging (NMRI).
- Ultrasound exam: A procedure in which high-energy sound waves (ultrasound) are bounced off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. The picture can be printed to be looked at later.
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 needle biopsy : The removal of tissue using a wide needle. This procedure may be guided using ultrasound, CT scan, or MRI.
- Incisional biopsy : The removal of part of a lump or a sample of tissue.
- Excisional biopsy : The removal of an entire lump or area of tissue that doesn’t look normal. A pathologist views the tissue under a microscope to look for cancer cells. An excisional biopsy may be used to completely remove smaller tumors that are near the surface of the skin. This type of biopsy is rarely used because cancer cells may remain after the biopsy. If cancer cells remain, the cancer may come back or it may spread to other parts of the body.
In order to plan the best treatment, the sample of tissue removed during the biopsy must be large enough to find out the type of soft tissue sarcoma and do other 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 and mid-grade tumors usually grow and spread more quickly than low-grade tumors.
Because soft tissue sarcoma can be hard to diagnose, parents should ask to have the tissue sample 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.
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 and whether the tumor has spread to other places in the body).
- The grade and size of the tumor, what part of the body it’s in, and how deep under the skin it is.
- The age of the patient.
- Whether the cancer has just been diagnosed or has recurred (come back).