[Congenital cholesteatoma of the petrous process and mastoid: a report of two cases].

Congenital cholesteatoma are unusual. They may arise in different sites of the temporal bone: petrous process, middle ear and mastoid. Primary cholesteatomas originate from embryonary ectodermal inclusions but the pathogenesis is not clear and many different hypotheses regarding its origin have been suggested. The clinical diagnosis is not easy if the tympanic membrane is normal, and computerized tomography and magnetic resonance imaging are useful. We report two cases of congenital cholesteatoma: One located in the petrous process and the other in the mastoid without affection of the tympanic cavity.