内視鏡的に摘除した直腸原発奇形腫の1例

Benign Solid Teratoma of the Rectum Removed with Endoscopic Polypectomy, Report of a Case

要旨　患者は66歳の女性で便秘を主訴として来院した．注腸X線検査では，直腸に大小2個のポリープがみられ，内視鏡では表面に毛髪を有する2個のポリープがみられた．生検では扁平上皮組織が得られ，奇形腫を疑い内視鏡的ポリペクトミーを施行した．ポリープは，37×27×34mm，15×13×21mmで，割面では嚢胞や歯牙がみられた．病理組織学的に2個のポリープとも直腸原発の成熟型奇形腫と診断した．直腸原発奇形腫は世界で36例の報告がみられる．本例は内視鏡的ポリペクトミーで摘除した最初の報告であるが，直腸原発の奇形腫に悪性化の報告がないことから有用な治療手段と考えられる．

　Teratoma originating in the digestive tract is an extremely rare disease. We encountered a case of teratoma which originated in the rectum and removed it by endoscopic polypectomy.

　The patient was a 66 year-old woman who visited our hospital with the chief complaint of constipation. Barium enema examination revealed one small polyp and one large polyp in the rectum (Fig. 1) and endoscopy disclosed two polyps with hair on their surface (Fig. 2a). Histological study of the biopsy specimens showed normal squamous epithelium, so teratoma was suspected. Then endoscopic polypectomy was performed. The polyps were 37×27×34 mm and 15×13×21 mm in size, with cysts and a tooth on their cut surface (Fig. 3b). Histopathologically, well-differentiated squamous epithelium, ganglion cells, smooth muscle, lymphatic folliculi, digestive tract, bronchial glands and adipose tissue were observed (Figs. 4,5). On the basis of these findings, the patient was diagnosed as having two mature teratomas originating in the rectum.

　There have been 36 reported cases of teratoma in the world originating in rectum. These patients ranged in age from 8 to 80 (mean age 35.6 years) and all except one were women. The clinical signs were prolapse of hair and polyp from the anus, bloody stool and constipation. Diagnosis has been made by digital examination, rectoscopy and barium enema examination. If the polyp includes hair and if biopsy reveals squamous epithelium, it can be strongly suspected to be a teratoma. This is the first report of a case of teratoma for which endoscopic polypectomy was done. The endoscopic polypectomy is considered to be an effective treatment since there has been noreport of malignant change in the teratoma of rectal origin.