Levenson M J, Michaels L, Parisier S C
Department of Otolaryngology, Manhattan Eye, Ear and Throat Hospital, New York, New York.
Otolaryngol Clin North Am. 1989 Oct;22(5):941-54.
Cholesteatomas (epidermoids) of the middle ear appearing medial to a normal tympanic membrane are identified in increasing numbers of young children. The evidence that these lesions are congenital in origin includes the young mean age of presentation, the normal appearance of the middle ear mucosa in almost all cases of small lesions, normal mastoid pneumatization documented by computerized tomography, the relatively large number of children with associated minor or major congenital malformations, and the consistent 3:1 ratio of males to females with the disorder in all of the large series reviewed. A direct relationship between congenital cholesteatomas (epidermoids) of the middle ear and the epidermoid formation is supported by the position of the epidermoid formation at a histologic transition zone in the anterior superior lateral quadrant of the tympanic cavity, which is also the site of greatest occurrence of congenital cholesteatomas. The epidermoid formation may not always involute and as it expands it would be expected to become visible medial to the tympanic membrane in the anterior superior quadrant. It seems evident that as the congenital cholesteatoma expands it can block the eustachian tube; during a bout of otitis media the tympanic membrane could perforate and the cholesteatoma could become secondarily infected. The congenital cholesteatoma in this situation would be difficult or impossible to distinguish from the more common acquired type.
越来越多的幼儿被发现中耳胆脂瘤（表皮样囊肿）出现在正常鼓膜内侧。这些病变起源于先天性的证据包括：发病的平均年龄小；在几乎所有小病变病例中中耳黏膜外观正常；计算机断层扫描显示乳突气化正常；有较多儿童伴有相关的轻微或严重先天性畸形；在所有回顾的大样本系列中，该疾病男女比例始终为3:1。中耳先天性胆脂瘤（表皮样囊肿）与表皮样形成之间存在直接关系，这一观点得到了以下事实的支持：表皮样形成位于鼓室前上外侧象限的组织学过渡区，而该区域也是先天性胆脂瘤最常发生的部位。表皮样形成可能不会总是消退，随着其扩大，预计会在鼓膜前上象限内侧变得可见。显然，随着先天性胆脂瘤的扩大，它会阻塞咽鼓管；在中耳炎发作期间，鼓膜可能穿孔，胆脂瘤可能继发感染。在这种情况下，先天性胆脂瘤很难或无法与更常见的后天性类型区分开来。
