ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Childhood Rhabdomyosarcoma. To see other pages, use the menu. Think of that menu as a roadmap to this full guide.
Soft tissue sarcoma (STS) is a cancer that develops in the tissues that support and connect the body. It can occur in fat, muscle, nerves, tendons, joints, blood vessels, or lymph vessels. Tumors begin when healthy cells change and grow out of control, forming a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread. In general, sarcomas are uncommon cancerous tumors, accounting for about 1% of all cancers.
Rhabdomyosarcoma is a type of STS that begins in mesenchymal cells, which areimmature cells that normally become muscle. It develops in a type of muscle called striated muscle. Striated muscles are the skeletal voluntary muscles, which are the muscles of the arms, legs, and rest of the body that people can control. Rhabdomyosarcoma is most frequently found in children and young adults.
Rhabdomyosarcoma can occur anywhere in the body:
Head and neck: about 40% of all rhabdomyosarcoma cases in children. This includes parameningeal sites (near the membranes covering the brain), 25%; eye socket, 8%; and other head and neck locations, 7%.
Urinary or reproductive organs: about 30% of cases
Arms or legs: about 15% of cases
Other sites: about 15% of cases. This includes the trunk (torso), intrathoracic (inside the lung and/or chest), biliary tract, retroperitoneal, pelvic, and perineal sites (close to the anus, vagina, and urinary structures).
Types of rhabdomyosarcoma
Each rhabdomyosarcoma tumor is classified as either favorable or unfavorable based on its histology, which is what the cells look like under a microscope. The terms “favorable” and “unfavorable” refer to the appearance of the cancer cells. In general, the more cancer cells look like normal cells, the more “favorable” they are and the greater the chance that treatment will be successful.
Favorable histology tumors include the following:
Embryonal rhabdomyosarcoma.This is the most common type of rhabdomyosarcoma, frequently found in the head and neck and in the reproductive and urinary organs.
Botryoid rhabdomyosarcoma. This is a subtype of embryonal rhabdomyosarcoma, found most often in hollow organs, such as the bladder or the vagina.
Spindle rhabdomyosarcoma. This is another subtype of embryonal rhabdomyosarcoma, found most often in the area around a boy’s testicles.
Unfavorable histology tumors include the following:
Alveolar rhabdomyosarcoma. This is a more aggressive type of rhabdomyosarcoma, found most often in the arms, legs, or trunk of the body.
Pleomorphic and undifferentiated rhabdomyosarcoma. These are the rarest types of rhabdomyosarcoma of children, found most commonly in the arms, legs, or trunk. This type of rhabdomyosarcoma is more common in adults.
This section covers rhabdomyosarcoma diagnosed in children. Learn more about soft tissue sarcoma in adults .
Looking for More of an Introduction?
If you would like more of an introduction, explore these related items. Please note these links will take you to other sections on Cancer.Net:
- Cancer.Net Patient Education Videos: View short videos on childhood cancer  and sarcoma  led by ASCO experts that provide basic information and areas of research.
The next section in this guide is Statistics . It helps explain how many people are diagnosed with this disease and general survival rates. Or, use the menu to choose another section to continue reading this guide.