Presentation
Hearing loss.
Patient Data
Within the right petrous apex is a large lobulated lesion with strikingly increased intrinsic T1 signal, heterogeneously low T2 signal and no contrast enhancement. The lesion demonstrates low DWI signal and diffusion values somewhat facilitated compared to normal brain parenchyma. It is separate from the inner ear structures and middle ear cavity.
Non-contrast CT demonstrates a large heterogeneous mass in the right petrous apex with very sharply demarcated and remodeled bony margins. It is separate from, but contacts, the internal carotid artery. Although the bone between it and the internal acoustic meatus is dehiscent, it appears centered on the petrous apex rather than the middle or inner ear.
Case Discussion
The patient went on to have a resection.
Histology:
MICROSCOPIC DESCRIPTION: Sections show multiple fragments of tissue which consists of organizing chronic inflammation with a prominent giant cell reaction with cholesterol crystals. In addition, there is a small amount of degenerate blood present. No evidence of epithelium or malignancy is seen.
FINAL DIAGNOSIS: Organizing chronic inflammation with a giant cell reaction to degenerate blood. No epithelium is identified. Features consistent with a cholesterol granuloma.
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