Contributor: Gordon K. Klintworth
Several conditions are associated with hyperlipoproteinemia or hyperlipidemia (cerebrotendinous xanthomatosis, hepatic triglyceride lipase deficiency, lecithin cholesterol acyl transferase deficiency, familial hypercholesterolemia [hypercholesterolemia - familial]). In these disorders increased quantities of lipid (neural lipid, triglycerides, cholesterol, cholesterol esters) are found within macrophages in certain tissues. Because the lipid becomes dissolved during the routine methods used to progess tissue these macrophages have a foamy cytoplasm. Accumulations of the lipid laden macrophages may produce a xanthoma. lipid laden macrophages are within the walls of arteries in attherosclerosis.
The Fredrickson classification of hyperlipoproteinemia recognizes 5 types of lipoproteinemia (hyperlipoproteinemia type I, hyperlipoproteinemia type II, hyperlipoproteinemia type III, hyperlipoproteinemia type IV, hyperlipoproteinemia type V). These types should not be confused with the different classification of various types of familial hyperlipoproteinemia (hyperlipoproteinemia - familial type 1, hyperlipoproteinemia - familial type 2, hyperlipoproteinemia - familial type 3, hyperlipoproteinemia - familial type 4, hyperlipoproteinemia - familial type 5).