Cholesterol Granuloma of the Mastoid: Case Report

Case 1 A 51-year-old woman presented with abrupt right-side hearing loss. Otoscopy revealed swelling of the wall of the extra-auditory canal and bulging of its cartilaginous wall. Excision of the wall, preformed at an outside clinic, led to the aspiration of blood. CT scans depicted a large lobulated expansile mass involving the right mastoid antrum and middle ear cavity, and extending to the right posterior cranial fossa. The overlying tegmen tympani and sigmoid sinus plate had bony defects, and there was thinning of the adjacent temporal and occipital bones. The mastoid bone showed sclerosis, and in the middle ear cavity there was underlying chronic inflammation (Fig. 1A). MR imaging of the temporal bone demonstrated a bilobular mass that showed high signal intensity at T1WI and heterogeneous mixed signal intensity at T2WI (Figs. 1B, C, D), and mastoidectomy and tympanoidectomy were performed. Histopathologic examination showed that the tumor was a cholesterol granuloma with soft brown fragments which were chronically inflamed and had cholesterol clefts (Fig. 1E).