Xanthelasma (pronounced “zan-the-las-ma”) is a non-cancerous growth made up of immune cells called histiocytes. Histiocytes are specialized cells that help remove waste products from the body. The histiocytes in a xanthelasma look much larger than normal histiocytes because they are full of lipids (fat). Xanthelasmas appear as small, yellow bumps on the upper, and sometimes lower, eyelids. Xanthelasma is a type of xanthoma.
The eyelid is a specialized area of the body designed to cover and protect the eye. The eyelid is made up of four layers: skin, skeletal muscle, tarsal plate, and conjunctiva. The skin of the eyelid is very thin and contains hair follicles. The subcutaneous tissue beneath the skin is very loose and unlike other areas of the body, it normally does not contain any fat. The skeletal muscle layer is connected to the scalp and is important for the movement of the eyelid. The tarsal plate is made up of connective tissue that provides structural support for the eyelid. The conjunctiva is a very thin layer on the inner portion of the eyelid that is connected directly with the tissue on the surface of the eye (also called the conjunctiva). The conjunctiva is important for both protecting and lubricating the eye.
Xanthelasma develops in people who have high blood cholesterol levels. These growths are especially common in people who have diabetes or other genetic conditions that lead to high blood cholesterol levels.
Xanthelasma usually occurs in patients who are middle-aged or older. However, if it occurs in younger patients, it may be a sign of familial hypercholesterolemia, which is a genetic condition resulting in high blood cholesterol levels.
Your doctor may suspect that a bump on your eyelid is a xanthelasma based on the look and location of the growth. The diagnosis can be confirmed after a small sample of tissue is removed in a procedure called a biopsy.
When examined under the microscope a xanthelasma is made up of many lipid-filled (fat-filled) histocytes. Pathologists sometimes describe these cells as foamy histiocytes because the inside of the cell looks like it is filled with a clear foam.
The diagnosis of xanthelasma is important because it may be the first sign that a patient has high blood cholesterol levels. If you have been diagnosed with xanthelasma, please talk with your doctor to see if additional tests for blood cholesterol are appropriate for you.