A Large Mastoid Cholesterol Granuloma Eroding the Dura and Sigmoid Sinus

Introduction: Large mastoid cholesterol granulomas, particularly aggressive ones, are rare. We present the first case of a mastoid cholesterol granuloma with a nonspecific clinical presentation, and aggressive behavior, destroying the petrous internal cortical plate, dura mater, and sigmoid sinus wall. Radiographic and histological examinations can help to distinguish such granulomas from others. Case presentation: A 50-year-old male presented with left otalgia, left blood-stained otorrhea, and a left temporal headache radiating to the mastoid. The radiographic examination revealed a left-sided, soft-tissue mass extending into the posterior fossa and compressing the sigmoid sinus inward. The histopathological features were consistent with a cholesterol granuloma. He underwent a cortical mastoidectomy to explore the lesion and macroscopic complete resection was achieved. Conclusion: This is the first case of a mastoid cholesterol granuloma eroding the dura and sigmoid sinus. This case illustrates the need to consider cholesterol granuloma in daily clinical practice. Such lesions can exhibit noncharacteristic features and have an aggressive nature.