Cholesterol metabolism in cholesteatoma and cholesterol granuloma.

Based on biochemical and morphological studies, the significance of cholesterol in cholesteatoma and cholesterol granuloma is discussed. In cholesteatoma, cholesterol is synthesized through desmosterol and delta 7-cholestenol (lathosterol), possibly in the matrix. Cholesterol crystal might have educed from keratin layers or a cell-disintegrated layer adjacent to the matrix by a physicochemical rather than by a biochemical process. Production of cholesterol in the matrix may differ depending on the cell cycle. In cholesterol granuloma, cholesterol may be derived from blood with some other compositions such as albumin and cholestanol, although other sources cannot be denied. Crystallized cholesterol is treated by the surrounding tissue as a foreign body; this results in formation of granuloma. The delta 7-cholestenol is not involved in the biosynthesis of cholesterol in cholesterol granuloma.