Xanthomas

Cutaneous xanthomas are yellow-brown, pinkish, or orange macules, papules, plaques, nodules, or infiltrations in tendons. They are

characterized histologically by accumulations of xanthoma cells—macrophages containing droplets of lipids. Xanthomas may be

symptoms of a general metabolic disease, a generalized histiocytosis, or a local fat phagocytosing storage process. The classification

of metabolic xanthomas is based on this principle: (1) xanthomas due to hyperlipidemia and (2) normolipidemic xanthomas. The

cause of xanthomas in the first group may be a primary hyperlipidemia, mostly genetically determined (Table 15-1), or secondary

hyperlipidemia, associated with certain internal diseases such as biliary cirrhosis, diabetes mellitus, chronic renal failure, alcoholism,

hyperthyroidism, and monoclonal gammopathy, or with intake of certain drugs such as beta-blockers and estrogens.

NOTE: TG, triglycerides; C, cholesterol; CM, chylomicrons; HDL, high-density lipoproteins; LDL, low-density lipoproteins; VLDL, very

low density lipoproteins; IDL, intermediate-density lipoproteins; +, raised; –, lowered.

Some of the xanthomas are associated with high plasma low-density lipoprotein (LDL)-cholesterol levels, and therefore with a

serious risk of atheromatosis and myocardial infarction. For that reason laboratory investigation of plasma lipid levels is always

necessary. In some cases an apoprotein deficiency is present. Table 15-2 shows correlations of clinical xanthoma type and

lipoprotein disturbances.

Xanthelasma

Most common of all xanthomas. In most cases an isolated finding unrelated to hyperlipidemia. Occurs in individuals >50 years;

however, when in children or young adults, it is associated with familial hypercholesterolemia (FH) or familial dysbetalipidemia (FD).

Synonyms: Xanthelasma palpebrarum, periocular xanthoma.

Skin lesions are asymptomatic. Soft, polygonal yellow-orange papules and plaques localized to upper and lower eyelids (Fig. 15-12)

and around inner canthus. Slow enlargement from tiny spots over months to years.

Xanthoma Tendineum

These subcutaneous tumors are yellow or skin-colored and move with the extensor tendons (Fig. 15-13). They are a symptom of

familial hypercholesterolemia (FH) that presents as type IIa hyperlipidemia. This condition is autosomal recessive with a different

phenotype in the heterozygote and homozygote. In the homozygote, the xanthomata appear in early childhood and the

cardiovascular complications in early adolescence; the elevation of the LDL content of the plasma is extreme. These patients rarely

attain ages above 20 years