MRI and CT in the evaluation of acquired and congenital cholesteatomas of the temporal bone.

Acquired (secondary) cholesteatomas of the middle ear and mastoid are usually a complication of chronic otomastoiditis and are often accompanied by infection from the outset, and their contents show evidence of some inflammatory reaction. Congenital (primary) cholesteatomas of the temporal bone are due to epithelial rest of embryonal origin. There are many sites of occurrence of congenital cholesteatomas (epidermoids) within the temporal bone: (1) middle ear, (2) mastoid, (3) middle ear and mastoid, (4) petrous bone, (5) the squama, and (6) within the tympanic membrane. Intradural (cisternal) congenital cholesteatomas are another type of cholesteatomas that often involve the cerebellopontine angle (CPA) region and cause varying degrees of cochlear and vestibular symptoms and signs. In this paper, we stress the role of magnetic resonance imaging (MRI) and computed tomography (CT) in the evaluation of acquired and congenital cholesteatomas of the temporal bone. It is our opinion that CT remains the study of choice for cholesteatomas of the middle ear cleft. MRI is superior to CT for the evaluations of infected cholesteatomas, petrous apex, and CPA cholesteatomas, as well as for the majority evaluation of cholesteatomatous involvement of the facial nerve, membranous labyrinth, and intracranial structures.