context: If you find a lump on your arms, legs, head, or neck, there's a small chance you could have a desmoid tumor. Unlike a fatty tumor that grows under your skin (called a lipoma), this kind of tumor develops in the fibrous tissue that makes up your tendons and ligaments. " Desmoid" comes from the Greek word desmos, which means tendon or band-like. Desmoid tumors are usually considered benign (not cancer) because they rarely spread to different parts of your body. But ones that grow fast (aggressive tumors) can be like cancer in some ways. They can grow into nearby tissues and can be fatal. These tumors can grow almost anywhere in your body and at any age. But they happen most often in women in their 30s. Only 2 to 4 people per million get one each year. People who have a condition called familial adenomatous polyposis ( FAP), an inherited type of colon cancer, are more likely than others to have them. People with this condition typically have desmoid tumors in the abdomen or colon. They're also linked to pregnancy, because of high levels of a hormone called estrogen, and to some kinds of severe injuries. The tumor also may be called one of the following: Aggressive fibromatosis Deep fibromatosis Desmoid fibromatosis Familial infiltrative fibromatosis Hereditary desmoid disease Musculoaponeurotic fibromatosis Signs of a desmoid tumor depend on where it is. If it's close to the surface of your skin, you may have a painless or slightly painful lump. If it's in your abdomen, it may be more aggressive. It can press against blood vessels and nerves and cause pain, a limp, or problems using your legs, feet, arms, or hands. It also can block your colon or grow into nearby tissues. When this happens, you may have severe pain, bleeding from your rectum, and other health problems. To find out what kind of tumor you have, doctors often go through these steps: Ultrasound: High-frequency sound waves are used to make images that will show if the tumor is solid. Imaging scans: These show whether the tumor is attached to other tissues and whether it can be safely removed with surgery. They include magnetic resonance imaging ( MRI), which uses powerful magnets and radio waves to make detailed images, and computerized tomography ( CT) scans, which put X-rays taken from several angles together to make a more complete picture. Biopsy: A small sample or the entire tumor is removed, and the cells are looked at under a microscope to confirm that it's a desmoid tumor. If you're diagnosed with a desmoid tumor, your doctor will recommend one of the following: Wait and watch: Some tumors don't grow, and some even get smaller on their own. If they're small and outside your belly -- and aren't causing symptoms -- your doctor may take this approach. Surgery: This is done when possible, though it can be difficult for tumors in the abdomen. As many as 25% to 50% come back to the same area after surgery. You may need other treatments as well. Radiation therapy: Used alone or with surgery or medicines or both, radiation is effective for many people. However, you may not be able to have it if the tumor is in your abdomen, because radiation can damage other important areas of your body. Radiofrequency ablation: Your doctor will put needles into the tumors and send radio waves through them to blast them with heat. This is a new approach and likely won't be the first one your doctor recommends. Medication: There isn't a standard drug treatment for desmoid tumors. But different types of medicines, including anticancer drugs, can be used to try to shrink them or stop them from growing. Cryoablation: A probe is used to freeze the tumor tissue.