A lipoma is a lump under the skin that occurs due to an overgrowth of fat cells. Lipomas are considered to be benign tumors, which means that they are rarely cancerous growths.
Lipomas can occur anywhere on the body where fat cells are present, but they tend to appear on the shoulders, chest, trunk, neck, thighs, and armpits. In less common cases, they may also form in internal organs, bones, or muscles. A person with a lipoma will typically feel a soft, oval-shaped lump just beneath the skin. Lipomas are usually painless unless they affect joints, organs, nerves, or blood vessels. In most cases, they do not cause other symptoms.