Chronic infection and granulation tissue lead to obstruction of the ventilatory passage congenital cholesteatoma originates from areas of keratinizing epithelium within the middle ear cleft;

• 乾燥无明显感染迹象的鼓膜穿孔状熊应视为慢性中耳炎的感染不活动期。先天性胆脂瘤多被认为来自胚胎期间残存于中耳裂的角质化扁平上皮。