A lipoma is a fatty lump that slowly grows between your skin and the muscle layer underneath. This tumor is common and forms beneath your skin, most often found in your upper body, arms, or thighs. A lipoma feels doughy and usually is not tender, though it moves with some finger pressure. Lipomas are typically noticeable in middle age and tend to run in families, so genetic factors likely play a factor in their development. Some people have more than one lipoma, though it is not cancer is usually harmless. If you have had a lipoma form and it bothers you, you may want it removed.