Cholesterol crystals in the temporal bone and the paranasal sinuses.

In order to study the manifestation and genesis of cholesterol deposits in the temporal bone and the paranasal sinuses, 137 temporal bones and 3 paranasal sinuses with deposits were examined. For histological study, 1036 specimens were obtained from temporal bones, and 16 specimens were obtained from paranasal sinuses. Several stages of a progressive foreign body reaction, including the appearance of histiocytes, granuloma formation and the development of granulation into scar tissue, were observed depending on the size and form of the crystals. Many large deposits were found in the temporal bones of patients with chronic non-suppurative lesions. Blue eardrum and hemotympanum were seen in the last stage of this foreign body reaction in these patients. Small deposits were found in the temporal bones and the paranasal sinuses of patients with chronic suppurative lesions. Most of these deposits were found in the obstructed parts. The pathogenesis of the cholesterol deposits is suspected to be fatty degeneration of the connective tissue.