Petrous Apex Cholesterol Granuloma

Fig. 24.1

Petrous apex cholesterol granuloma. (a) Axial CT image with contrast enhancement. (b) Coronal CT image with contrast enhancement. (c) Axial T1-weighted gadolinium-enhanced image. (d) Coronal T1-weighted gadolinium-enhanced image. There is an ovoid cystic lesion in the right petrous apex, containing predominantly T1-hyperintense material. The right internal carotid artery is displaced anteriorly

Fig. 24.2

Petrous apex cholesterol granuloma. (a) Axial CT image with contrast enhancement. (b) Axial FLAIR image. (c) Sagittal T1-weighted gadolinium-enhanced image. (d) Coronal T1-weighted gadolinium-enhanced image. There is an expansile cystic lesion in the left petrous apex containing T1-hyperintense material. The cyst expanded to the clivus body with anterior displacement of the left cavernous internal carotid artery. Posteriorly, the cyst indents the brainstem

24.3 Histopathology

Chocolate-colored fluid contents are often grossly observed.
Petrous apex cholesterol granulomas are characterized by cholesterol clefts surrounded by histiocytes, lymphocytes, plasma cells, and multinucleated foreign-body giant cells [9].
Areas of old hemorrhage and inflammation with hemosiderin-laden macrophages are typically observed (Fig. 24.3) [10].

Fig. 24.3

In a petrous apex cholesterol granuloma, a large number of submucosal spindle-shaped, empty clefts surrounded by inflammatory cells are shown. The intact respiratory epithelium is noted (arrowhead). Focal hemorrhage (large arrows) and hemosiderin-laden macrophages (small arrows) are also shown (H&E stain, ×100) (Adapted from Chao [10]; with permission)