Rhabdomyosarcoma is a rare cancer that forms in the body’s soft tissues, such as muscle and connective tissue. In rhabdomyosarcoma, the cancer cells look similar to immature muscle cells. Rhabdomyosarcoma can occur at any age, but it most often affects children and young adults. Rhabdomyosarcoma most commonly forms in the:
Where rhabdomyosarcoma begins and the characteristics of the cells involved in the cancer helps determine your treatment options. Treatment options for rhabdomyosarcoma include chemotherapy, surgery and radiation therapy. 
There are two main types of pediatric rhabdomyosarcoma: embryonal rhabdomyosarcoma and alveolar rhabdomyosarcoma.
Rhabdomyosarcoma is the most common soft tissue cancer in children, with approximately 350 new cases each year in the United States. 
Signs and Treatments
Signs and symptoms may be caused by childhood rhabdomyosarcoma or by other conditions. The signs and symptoms that occur depend on where the cancer forms. Check with your child’s doctor if your child has any of the following:
The following tests and procedures may be used:
If these tests show there may be a rhabdomyosarcoma, a biopsy is done. A biopsy is the removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer. Because treatment depends on the type of rhabdomyosarcoma, biopsy samples should be checked by a pathologist who has experience in diagnosing rhabdomyosarcoma.
One of the following types of biopsies may be used:
The following tests may be done on the sample of tissue that is removed:
The prognosis (chance of recovery) and treatment options depend on the following:
For patients with recurrent cancer, prognosis and treatment depend on the following:
-via Mayo Clinic Rhabdomyosarcoma Definition
 -via St. Baldrick’s Foundation
 -via http://www.cancer.gov/