多発微小大腸腫瘍性病変を認めた遺伝性非ポリポーシス大腸癌（HNPCC）の2例―実体顕微鏡による検索

Minute Neoplastic Lesions Detected by Stereomicroscopic Examination in Patients with Hereditary Nonpolyposis Colorectal Cancer (HNPCC)

要旨　遺伝性非ポリポーシス大腸癌と考えられた多発大腸癌の2例を報告した．〔症例1〕は80歳の女性で，長女と次男が大腸癌に罹患していた．74歳時に横行結腸の2型進行癌，78歳時に直腸S状部に2型進行癌とⅡa型sm癌の治療を受けていた．経過観察のための大腸X線・内視鏡検査で，下部直腸と肝彎曲部に2型進行癌を，他の部位にも表面隆起型早期癌の多発を認め，大腸全摘術が行われた．〔症例2〕は80歳の女性で，姉が49歳時に大腸癌の切除を受けていた．貧血のため大腸検査を行ったところ，上行結腸と下行結腸に進行癌を，横行結腸にⅡa型の早期癌を認め，結腸亜全摘を行った．2例の全切除標本を実体顕微鏡を用いて詳細な組織学的検索を行ったところ，〔症例1〕からは合計31個の癌巣（進行癌4個，sm癌4個，m癌23個）と3個の腺腫が，〔症例2〕では3個の進行癌と1個のm癌，23個の腺腫が発見された．2例とも右側結腸に腫瘍の頻度が高かった．5mm以下の微小病変では，〔症例2〕の腺腫は半球状隆起を示したが，〔症例1〕のm癌の多くが高低差のない平旭な形態であった．HNPCC患者の大腸検査では，平坦な微小腫瘍の存在を考慮した全大腸の観察が必要と考えられた．

　We present two cases with hereditary nonpolyposis colorectal cancer (HNPCC). A 80-year-old woman〔Case 1〕who underwent colectomy twice due to metachronous colon cancers visited to our hospital for follow-up. Her son and daughter had operations for colon cancer at their age of less than 50. Total colonoscopic examination revealed multiple cancers in the remnant colo-rectum, she underwent total proctocolectomy. A stereomicroscopic examination of the entire resected specimen revealed 31 lesions as a total including 17 minute adenocarcinomas less than 5 mm in size, and three adenomas. Most minute cancers showed nonpolypoid growth or flat elevation, and were located in the rightsided hemicolon. Another 80-year-old woman〔Case 2〕was admitted to our hospital due to anemia. Her eldest sister was operated for colon cancer at her age of less than 50. Endoscopic and radiologic examinations revealed multiple cancers in the ascending colon and descending colon, she underwent total colectomy. A stereomicroscopic study of the resected specimen showed four cancers and 23 adenomas including 21 minute adenomas less than 5 mm in size. These minute adenomas showed polypoid growth or hemispheric elevation, and were mainly located in the right sided colon. Our results indicate that total colonoscopic examination seems necessary for patients with HNPCC to detect minute nonpolypoid neoplasms.