Abstract
Xanthomas are clusters of foam cells located in connective tissue. They arise from the transformation of macrophages which take up oxidatively modified lipoproteins, especially LDL (ox-LDL), by means of specific ("scavenger") receptors.
Another mechanism of foam cell formation is phagocytosis of LDL aggregates or LDL complexes with antibodies. The origin of xanthomas is similar to the development of the early stage of an atherosclerotic lesion.
Tendon and tuberous xanthomas are specific for autosomal dominant familial hypercholesterolemia (FH). Eruptive xanthomas are a skin manifestation of severe hypertriglyceridemia and signal the risk of acute pancreatitis and the manifestation of diabetes.
Xanthoma striatum palmare is a pathognomonic manifestation of primary dys-β-lipoproteinemia. Tendon and tuberous xanthomas are further specific for rare disorders such as cerebrotendinous xanthomatosis and familial β-sitosterolemia.
Increased concentrations of LDL-cholesterol, or phytosterols (in sitosterolemia) and cholestanol (in cerebrotendinous xanthomatosis), and their depositions in tissues are associated with the development of xanthomas, atheromatous plaques and premature atherosclerosis. Xanthelasma palpebrarum, until recently considered as a cosmetic lesion, is associated with a 15-year reduction in the average life expectancy by 15 years, increases the risk of atherosclerotic cardiovascular diseases by more than 40%, and is also often associated with non-alcoholic steatosis of the liver.
The presence of tendon xanthomas in patients with FH which was proven by molecular biological methods increased the risk of cardiovascular disease 2-4 times compared to individuals with FH without tendon xanthomas. Necrobiotic xanthogranuloma, diffuse plane xanthomas and normolipidemic xanthomas are often associated with paraproteinemia and lymphoproliferative disorders.