FIG 2. Cholesterol granuloma.

A, Axial CT scan shows a smoothly marginated expansile lesion (arrows) centered within the petrous apex, in contradistinction to a PAC, in which the mass is centered within the posterior portion of Meckel's cave and secondarily extends into the petrous apex.

B, Axial T1-weighted MR image confirms marked T1 shortening within the lesion (arrows), characteristic of cholesterol granuloma. Diagnosis was proved at surgical exploration.