General Information About Osteosarcoma and Undifferentiated Pleomorphic Sarcoma (UPS) (Formerly Called Malignant Fibrous Histiocytoma [MFH]) of Bone

Osteosarcoma and undifferentiated pleomorphic sarcoma (UPS) of bone are diseases in which malignant (cancer) cells form in bone.

Osteosarcoma usually starts in osteoblasts, which are a type of bone cell that becomes new bone. Osteosarcoma is most common in adolescents. It commonly forms in the ends of the long bones of the body, which include bones of the arms and legs. In children and adolescents, it often forms in the long bones, near the knee. Rarely, osteosarcoma may be found in soft tissue or organs in the chest or abdomen.

Osteosarcoma is the most common type of bone cancer. UPS (formerly called malignant fibrous histiocytoma [MFH]) is a rare type of bone cancer that usually starts in soft tissue, but it may form in bone. In bone, UPS cells look similar to osteosarcoma under a microscope. UPS is treated like osteosarcoma.

Ewing sarcoma is another kind of bone cancer, but it is not covered in this summary. For more information, see Ewing Sarcoma Treatment.

Having past treatment with chemotherapy or radiation can increase the risk of osteosarcoma.

Anything that increases a person's risk of getting a disease is called a risk factor. Not every child with one or more of these risk factors will develop osteosarcoma, and it will develop in some children who don't have any known risk factors. Talk with your child's doctor if you think your child may be at risk. Risk factors for osteosarcoma include the following:

• Past treatment with chemotherapy or radiation therapy.
• Having a certain change in the RB1 gene.
• Having certain conditions, such as the following:
  • Bloom syndrome.
  • Diamond-Blackfan anemia.
  • Li-Fraumeni syndrome.
  • Paget disease.
  • Hereditary retinoblastoma.
  • Rothmund-Thomson syndrome.
  • Werner syndrome.

Signs and symptoms of osteosarcoma and UPS include swelling over a bone or a bony part of the body and joint pain.

These and other signs and symptoms may be caused by osteosarcoma or UPS or by other conditions. Check with a doctor if your child has any of the following:

• Swelling over a bone or bony part of the body.
• Pain in a bone or joint.
• A bone that breaks for no known reason.

Imaging tests are used to detect (find) osteosarcoma and UPS.

In addition to asking about your child's personal and family health history and doing a physical exam, your child's doctor may perform the following tests and procedures:

• X-ray: An x-ray of the organs and bones inside the body. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
• 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.
• 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).

A biopsy is done to diagnose osteosarcoma.

Imaging tests are done before a biopsy.

Cells and tissues are removed during a biopsy so they can be viewed under a microscope by a pathologist to check for signs of cancer. It is important that the biopsy be done by a surgeon who is an expert in treating cancer of the bone. It is best if that surgeon is also the one who removes the tumor. The biopsy and the surgery to remove the tumor are planned together. The way the biopsy is done affects which type of surgery can be done later.

The type of biopsy that is done will be based on the size of the tumor and where it is in the body. There are two types of biopsy that may be used:

• Core biopsy: The removal of tissue using a wide needle.
• Incisional biopsy: The removal of part of a lump or a sample of tissue that doesn't look normal.

The following test may be done on the tissue that is removed:

• 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 may affect prognosis (chance of recovery) and treatment options.

The prognosis may be affected by certain factors before and after treatment.

The prognosis of untreated osteosarcoma and UPS may depend on the following:

• Where the tumor is in the body and whether tumors formed in more than one bone.
• Whether the patient has two or more tumors in the same bone.
• The size of the tumor.
• Whether the cancer has spread to other parts of the body and where it has spread.
• The type of tumor (based on how the cancer cells look under a microscope).
• The patient's sex, age, and weight at the time of diagnosis.
• Whether the patient has had treatment for a different cancer.
• Whether the patient has certain genetic diseases.

After osteosarcoma or UPS is treated, prognosis also depends on the following:

• How much of the cancer was killed by chemotherapy.
• Whether the tumor has been completely removed by surgery.
• Whether the cancer has recurred (come back) within 2 years of diagnosis.

Treatment options for osteosarcoma and UPS depend on the following:

• Where the tumor is in the body and if it has spread.
• The size of the tumor.
• The grade of the cancer.
• Whether the bones are still growing.
• The patient's age and general health.
• The desire of the patient and family for the patient to be able to take part in activities such as sports or to look a certain way.
• Whether the cancer is newly diagnosed or has recurred after treatment.