It is found at staged operation that residual cholesteatoma is more frequently encountered at some anatomic sites such as the anterior epitympanum, oval window niche, and hypotympanum near the Eustachian tube.

• 由阶段手术得到的经验显示上鼓室之前侧、卵圆窗及下鼓室靠近耳咽管处是胆脂瘤容易残留的部位。