Lipid Composition of Intracranial Tumors

Abstract

A tumor is an entity separate from the substrate tissue on which it is growing, with a characteristic composition and metabolism. Among various strains, the more rapidly growing tumors contain more phospholipid and less cholesterol and neutral fat than slowly growing ones (1, 2). The outer growing portion of a tumor has the higher phospholipid content, while the central necrotic portion has the higher content of cholesterol, cholesterol ester, neutral fat, and water (3, 4). Malignant tumors have a higher content of phospholipid and cholesterol than benign ones or the tissues on which they are growing (5–8). The qualitative composition is influenced by diet, since the degree of unsaturation of the fatty acids may be raised or lowered by changing the type of food fat (9). Whereas the phospholipid of liver and intestinal mucosa has a rapid rate of turnover, indicating a metabolic significance, the phospholipid of tumors has a slow rate of turnover similar to that of brain and muscle, which indicates that it has principally a structural significance (10). Intracranial tumors offer the opportunity to compare the lipid composition of a tumor with a substrate tissue having a very high lipid content. Materials and Methods The tumors of this series were obtained from operations and autopsies. The methods of Bloor (11) were used for the determination of phospholipid, total cholesterol, total fatty acid, and neutral fat. Cerebroside was determined by Kimmelstiel9s method (12). Phospholipid represents the total acetone-insoluble lipid, which includes lecithin, cephalin, sphingomyelin, and cerebroside.