Congenital Mastoid Cholesteatoma With Giant Intracranial Extension: A Case Report.

Cholesteatomas are keratinizing cystic lesions of the temporal bone, most commonly involving the middle ear and mastoid. Intracranial extension is rare and usually associated with acquired disease, while giant supratentorial presentations are exceptional. We report a well-documented and neuroradiologically illustrated case of an exceptionally large congenital mastoid cholesteatoma with supratentorial intracranial extension. A 49-year-old woman presented with left parietal bone softening and recent ipsilateral facial sensory disturbance. MRI revealed a giant left temporoparietooccipital extra-axial mass (71 × 59 × 89 mm) with extensive calvarial destruction, extension from the mastoid, near-complete transverse sinus compression, and an 8-mm midline shift. She underwent a left parietooccipital craniotomy with complete evacuation of a tumor mass. Histopathology was consistent with cholesteatoma, and follow-up MRI at two months showed no residual or recurrent lesion. Clinically, she improved, with only mild residual conductive hearing loss and gradually resolving sensory symptoms. To our knowledge, no cases with comparable dimensions have been previously reported. This case complements the existing literature by representing the extreme upper end of the size spectrum of primary intracranial cholesteatomas.