A lipoma is a benign tumor made of fat tissue. They are generally soft to the touch, movable, and painless. They usually occur just under the skin but occasionally may be deeper. Most are less than 5 cm in size. Common locations include upper back, shoulders, and abdomen. A few people have a number of lipomas. The cause is generally unclear. Risk factors include family history, obesity, and not enough exercise. Diagnosis is typically based on a physical exam. Occasionally medical imaging or tissue biopsy is used to confirm the diagnosis. Treatment is typically by observation or surgical removal. Rarely the condition may recur following removal, however, this can generally be managed with repeat surgery. They are not generally associated with a future risk of cancer.