Relationship between Pars Flaccida Cholesteatoma and Middle Ear Aeration in Human Temporal Bone Pathology

Abstract

Obstruction of the tympanic isthmus has been considered to play an important role in the development of cholesteatoma. However, it has recently been demonstrated by high resolution computed tomography that obstruction of the tympanic isthmus is not necessary for the etiology and progression of pars flaccida cholesteatoma. Therefore, histopathological changes in the epithelium and aeration of the middle ear was observed using seventeen human temporal bones obtained from cholesteatoma and retraction pocket cases. Inflammatory change occurs with high frequency in the lateral portion of incus and is less frequent in the tympanic isthmus. Obstruction of aeration in the lateral portion of the incus was very frequent, but in the tympanic isthmus, was rare. This study showed that the cause of retraction pocket and pars flaccida cholesteatoma is not only obstruction of the tympanic isthmus but also dysfunction of the Eustachian tube and local obstruction of aeration in the middle ear.