A lipoma is a benign (noncancerous) lump that forms due to an overgrowth of fat cells. These lumps typically develop just beneath the skin in the fatty layer and can appear anywhere on the body where fat cells are present, such as the neck, shoulders, back, abdomen, arms, and thighs. Lipomas feel soft, rubbery or doughy to the touch, are usually dome-shaped, and can move slightly when pressed. They typically grow slowly over months or years and are generally small, about 1 to 5 cm in diameter, but can sometimes grow larger. Lipomas are usually harmless and do not cause pain unless they press on nearby nerves or contain many blood vessels. They most commonly occur in people between the ages of 40 and 60 and affect about 1 in 100 people. The exact cause is unknown, but there may be an inherited genetic component in some cases. Most people do not need treatment for a lipoma unless it causes pain, grows larger, or is cosmetically concerning. Removal might involve minor surgery. It is important to have any new lumps checked by a doctor to confirm the diagnosis and rule out other conditions, including rare cancerous tumors called liposarcomas. In summary, a lipoma is a benign, slow-growing fatty tumor under the skin that is generally harmless but may sometimes require medical evaluation or removal for symptoms or cosmetic reasons.