A xanthoma (pronounced “zan-thoma”) 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 xanthoma look much larger than normal histiocytes because they are full of lipids (fat).
Xanthomas can develop anywhere in the body but they are most commonly found in the skin, stomach, colon, and bladder. In the skin or around joints, xanthomas appear as yellow bumps.
Xanthomas that arise in the skin are often associated with high blood cholesterol levels. For this reason, these growths are common in patients who have diabetes or other genetic conditions that lead to high blood cholesterol levels. Treatment that leads to lowered blood cholesterol levels can cause the xanthomas to shrink or even disappear.
Doctors divide xanthomas into types based on their location and clinical features. The following is a list of the most common types.
When they arise on the skin, the diagnosis is usually made after the xanthoma has been removed and sent to a pathologist to examine under the microscope. In other parts of the body, such as the stomach or bladder, the diagnosis is usually made when a tissue sample is examined for another reason.
When examined under the microscope a xanthoma 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 xanthoma is important because it may be the first clue that a patient has high blood cholesterol levels. If you have been diagnosed with xanthoma, please talk with your doctor to see if additional tests for blood cholesterol are appropriate for you.