Rhabdomyosarcoma - Childhood: Diagnosis

Approved by the Cancer.Net Editorial Board, 04/2016

ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of the medical problem. To see other pages, use the menu

Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If this happens, it is called metastasis. For example, imaging tests can show if the cancer has spread. Imaging tests show pictures of the inside of the body. Doctors may also do tests to learn which treatments could work best.

For most types of cancer, a biopsy is the only sure way for the doctor to know whether an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.

This list describes options for diagnosing this type of cancer, and not all tests listed will be used for every person. Your child’s doctor may consider these factors when choosing a diagnostic test:

  • The type of cancer suspected

  • Your signs and symptoms

  • Your age and medical condition

  • The results of earlier medical tests

In addition to a physical examination, the following tests may be used to diagnose rhabdomyosarcoma:

  • Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. The type of biopsy performed will depend on the location of the cancer. If the tumor is near the surface of the body, the child will be given a local anesthetic to numb the area during the procedure; if it is deeper inside the body, a general anesthetic (medication to block the awareness of pain) will be used. A pathologist then analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.

  • Immunocytochemistry tests. These are special stains done on the cells taken during the biopsy to help the doctor make an accurate diagnosis of rhabdomyosarcoma. Stains that show muscle cell development, including actin, desmin, MyoD-1, and Myogenin, are most helpful.

  • Genetic tests of tumor tissue. Chromosomes are structures that contain the genes in a cell. Changes in certain chromosomes in the tumor cells, called chromosomal translocations, can help doctors identify the alveolar subtype of rhabdomyosarcoma (see Introduction), although some alveolar rhabdomyosarcomas lack any specific translocation. Doctors will do a genetic test of the tumor tissue, usually fluorescence in-situ hybridization (FISH test) to see if translocations have occurred.

  • Bone marrow biopsy. The doctor may also perform a bone marrow biopsy. Rhabdomyosarcoma can spread to the bone marrow, and only a biopsy can find it there. Bone marrow has both a solid and a liquid part. A bone marrow biopsy is the removal of a small amount of solid tissue using a needle. The sample(s) are then analyzed by a pathologist. A common site for a bone marrow biopsy is the pelvic bone, which is located in the lower back by the hip. The skin in that area is usually numbed with medication beforehand, and other types of anesthesia may be used.

Imaging tests

To determine where the cancer is located and if it has spread, the doctor may use some of the following imaging tests:

  • X-ray. An x-ray is a way to create a picture of the structures inside of the body using a small amount of radiation.

  • Computed tomography (CT or CAT) scan. A CT scan creates a 3-dimensional picture of the inside of the body using x-rays taken from different angles. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. A CT scan can also be used to measure the tumor’s size. Sometimes, a contrast medium (a special dye) is injected into a patient’s vein or given orally (by mouth) to provide better detail.

  • Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein or given orally (by mouth) to create a clearer picture.

  • Bone scan. A bone scan uses a radioactive tracer to look at the inside of the bones. The tracer is injected into a patient’s vein. It collects in areas of the bone and is detected by a special camera. Healthy bone appears gray to the camera, and areas of injury, such as those caused by cancer, appear dark.

  • Positron emission tomography (PET) or PET-CT scan. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body. This substance is absorbed mainly by organs and tissues that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. A scanner then detects this substance to produce images of the inside of the body.

After these diagnostic tests are done, your child’s doctor will review all of the results with you. If the diagnosis is cancer, these results will also help the doctor describe the cancer; this is called the stage.

The next section in this guide is Stages and Groups. It explains the system doctors use to describe the extent of the disease. Or, use the menu to choose another section to continue reading this guide.