Differential Clinical and Radiographic Features of Cholesterol Granulomas and Cholesteatomas of the Petrous Apex

Cholesterol granulomas and cholesteatomas are expansile, destructive lesions of the petrous apex that occur more frequently than we previously realized. Having obscure causes, they grow silently, often reaching impressive proportions, until they encroach on adjacent cranial nerves or the otic capsule. The lesions have distinguishing histopathologies, early clinical manifestations, and neuroradiographic features that, when integrated, allow for a critical preoperative differentiation. Cholesterol granulomas are treated effectively through internal marsupialization into the mastoid or middle ear cavity. Cholesteatomas, however, are managed usually by a much more aggressive and complicated exteriorization or exenteration. Selected case reports are used to emphasize salient clinical and radiographic features and perioperative management.