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. Use the menu to see other pages. Think of that menu as a roadmap for this entire guide.

About sarcoma

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. Cancer begins 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, accounting for about 1% of all cancers.

About rhabdomyosarcoma

Rhabdomyosarcoma is a type of STS that begins in mesenchymal cells, which are immature 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 locations: 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. It is frequently found in the head and neck and in the reproductive and urinary organs.

• Botryoid rhabdomyosarcoma. This is a subtype of embryonal rhabdomyosarcoma that is found most often in hollow organs, such as the bladder or the vagina.

• Spindle rhabdomyosarcoma. This is another subtype of embryonal rhabdomyosarcoma that is found most often in the area around a person’s testicles.

Unfavorable histology tumors include the following:

• Alveolar rhabdomyosarcoma. This is a more aggressive type of rhabdomyosarcoma that is found most often in the arms, legs, or trunk of the body. An alveolar rhabdomyosarcoma can be subdivided based on its genetic pattern. The doctor will run specialized testing on your child's tumor tissue to determine if there are any unique gene fusions present and may recommend different treatments based on the molecular pattern of your child's tumor (see Types of Treatment).

• Pleomorphic and undifferentiated rhabdomyosarcoma. These are the rarest types of rhabdomyosarcoma in children. They are 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 that 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 the number of people who are diagnosed with this disease and general survival rates. Use the menu to choose a different section to read in this guide.