直腸原発と思われる奇形腫の1例

Teratoma of the Rectum, Report of a Case

要旨　患者は76歳，女性．主訴は下血．大腸内視鏡検査で直腸に表面に数本の毛髪を有する腫瘤があり，生検の結果，重層扁平上皮に覆われていた．腹部単純写真，注腸造影，CTで腫瘤内石灰化が認められ，直腸奇形腫と診断し，腫瘤摘出術を施行した．腫瘤は33×24×22mm大で，左卵管の背側で卵巣と15mmの索状物で連続していた．病理組織検査で腫瘤の表面は扁平上皮で覆われ，内部には結合組織，腺組織，神経組織，骨組織などが含まれていた．卵巣には異常はなく，病理組織学的検討の結果，直腸原発の成熟型奇形腫と考えた．直腸原発奇形腫は自験例を含めると本邦で11例，世界で40例報告されている．この中には経肛門的に摘出したものもあり，卵巣との連続性を明確にしていないものがある．卵巣奇形腫の直腸穿破例も報告があるため，原発性と診断するには開腹下に卵巣奇形腫の有無や位置関係を明確にする必要がある．

　A 76-year-old woman was admitted to our hospital on February 6, 1986 because of massive rectal bleeding. Emergency colonoscopy showed an elastic hard tumor in the rectum. Its smooth surface was covered with squamous epithelium exhibiting shafts of hair (Fig. 2). The calcifications inside the tumor (Fig. 7) were revealed by barium enema study (Fig. 3) and computed tomography (Fig. 4). We diagnosed it as teratoma of the rectum. Surgical excision of the tumor was performed. The tumor, 33×24×22 mm in size, was located on the anterior wall and a cord-like material was attached to the tumor (Fig. 6). Her ovaries were normal and there was not any ovarian tumor which might have ruptured into the rectum. Histological findings (Fig. 9) showed that the tumor was composed of mature connective, glandular, neural, osteal and other tissues.

　Forty cases (11 in Japan) of teratoma arising in the rectum have been reported in the world literature. The diagnosis of primary rectal teratoma should be decided by exclusion of ovarian teratoma ruptured into the rectum, and when transanal operative or endoscopic resection cannot confirm whether it primarily arises in the rectum or not.