xanthoma

xanthoma A firm yellow, orange, or brown nodule deep in the skin (such as around the Achilles tendon, elbows, or knees) or mucous membrane caused by fat deposition. Although xanthomas themselves are harmless, they frequently indicate underlying disease, such as diabetes, lipid disorders (such as elevated blood cholesterol levels), or other conditions. They are composed of lipid-laden foam cells called histiocytes. Treatment is directed toward any underlying disorder when present. The nodules can be resected surgically for cosmetic purposes. Xanthoma is distinguished from xanthelasma by being a large nodule deep in the tissues as opposed to a plaque on the skin surface, but both can occur from lipid disorders. See also xanthelasma.