外耳道骨腫の1症例

A Case of Osteoma of the External Auditory Canal

　はじめに

　外耳道における骨性腫瘍の発生頻度は低く，その中でも外耳道骨腫は比較的稀な疾患とされている。今回われわれは骨腫による外耳道閉鎖により伝音性難聴をきたし，手術的治療を行い良好な経過をとった症例を経験し，外耳道骨腫の病理学的特徴について若干の知見を得たので文献的考察を加え報告する。

A 20-year-old male patient presented with an osteoma of the external auditory canal with conduc-tive hearing loss. The osteoma was removed, and hearing recoverd to the normal range. T1-weighted MRI revealed that the tumor of the external audi-tory canal consisted of 2 different kinds of den-sities : inner low-and outer high-density areas. The outer area and a part of the inner area were enhan-ced by Gd-Tl-weighted MRI. The MRI findings were comparable to the pathology of the spon-genous type osteoma. According to previous reports, most of the osteomas of the external auditory canal were the spongenous type, while most cases of the temporal bone and paranasal cavity were the ivory or mixed type.