<prompt> Cholesteatoma commonly perforates -Lat. semicircular canalSup. semicircular canalPromontoryOval window  <response>: Cholesteatoma has the property to destroy the bone by virtue of the various enzymes released by it.Structures immediately at the risk of erosion are: Long process of incus.Q Fallopian canal containing facial nerve. Q Horizontallateral semicircular canal. Q 