There is a continuous mucosa between the middle ear and mastoid process. After the middle ear is infected with purulent infection, the mastoid mucosa also has an inflammatory reaction. It is catarrhal at first, and there may be mild tenderness in the mastoid area. After the tympanic membrane is perforated and pus is discharged, the mastoid inflammation reaction disappears immediately. If the pus is not drained smoothly, or if there is infection with type III pneumococcus, which is very toxic and destroys the bone, the mastoid cell mucosa becomes edematous, bleeding, necrotic and suppurative, it becomes acute suppurative mastoiditis, which is actually the sequel of acute otitis media and should be called acute suppurative otitis media and mastoiditis.