A soft, round swelling or tumor composed of fat cells, occurring in the skin. The fat tissue is enclosed in a fibrous capsule. Usually solitary, but sometimes multiple, lipomas vary is size from minute growths to huge masses weighing several pounds.

They may occur from early age to advanced age, but from 40 to 50 percent appear between the ages of 30 and 40, when the body begins to accumulate excess fat, at which time the incidence of these benign tumors is about twice as high in women as in men. In some cases they are associated with endocrine and neurological disturbances.

Lipomas occur typically on the neck, back, shoulders, and abdominal wall; they occur only rarely on the face, scalp, hands, and feet. As a rule such lumps cause a few symptoms, but in areas such as the inner surface of the thighs they may form pendulous masses.

Lipomas may be associated also with muscles or with the larger joints. Internal lipomas---on the intestine, for instance---are relatively uncommon. Malignant change is rare. Since lipomas do not infiltrate adjacent areas, surgical removal is usually a simple procedure.