Xanthoma is a skin condition in which fat builds up under the surface of the skin.

Xanthomas are common, particularly among older adults and persons with high blood lipids.

Xanthomas vary in size. Some are very small, while others are bigger than 3 inches in diameter. They may appear anywhere on the body, but are most often seen on the elbows, joints, tendons, knees, hands, feet, or buttocks.

They may be a sign of a medical condition that involves an increase in blood lipids. Such conditions include:

• Diabetes
• Primary biliary cirrhosis
• Certain cancers
• Inherited metabolic disorders such as familial hypercholesterolemia

Xanthelasma palpebra is a common type of xanthoma that appears on the eyelids.

A xanthoma looks like a sore or bump under the skin. It's usually flat, soft to the touch, and yellow in color. It has sharp, distinct edges.

Your doctor will examine the skin. Usually, your doctor can diagnose a xanthoma simply by looking at your skin. A biopsy of the growth will show a fatty deposit.

If you have a disease that causes increased blood lipids, treating the condition may help reduce the development of xanthomas.

If the growth bothers you, your doctor may remove it. However, xanthomas may come back after surgery.

The growth is non-cancerous and painless, but may be a sign of another medical condition.

The growth may cause a change in how you look. This is called cosmetic disfiguring.

Call your health care provider if xanthomas develop. They may indicate an underlying disorder that needs treatment.

Control of blood lipids, including triglycerides and cholesterol levels, may help to reduce development of xanthomas.

Goldman L, Ausiello D. Cecil Textbook of Medicine. 22nd ed. Philadelphia, Pa: WB Saunders; 2004.

Habif TP. Clinical Dermatology. 4th ed. St. Louis, Mo: Mosby; 2004.