Development of Cholesterol Granuloma in a Temporal Bone Petrous Apex Previously Containing Marrow Exposed to Air Cells

Abstract

There is ongoing debate on the pathogenic mechanisms of cholesterol granuloma formation in the temporal bone. The purpose of this report is to provide evidence in support of the exposed marrow hypothesis in explaining the pathogenesis of petrous apex cholesterol granuloma. Retrospective single case study. The primary outcome evaluated was the diagnosis of a new cholesterol granuloma in a petrous apex that previously demonstrated radiologic evidence of bone marrow exposed to petrous apex air cells. A patient with a unilateral petrous apex cholesterol granuloma develops a new, contralateral cholesterol granuloma in a hyperpneumatized temporal bone petrous apex shown previously to have medullary bone exposed to air cells. This report implicates the medullary-air cell interface in a hyperaerated temporal bone petrous apex in the development and growth of a petrous apex cholesterol granuloma.