肛門管腫瘍の診断（内視鏡，肛門鏡，肉眼を含めて）

Endoscopic, Anoscopic, and Macroscopic Morphologic Clues for the Diagnosis of Anal Canal Cancers

要旨●肛門管腫瘍は，痔核や裂肛などの良性疾患と外観が類似することが多く，診断の遅延を招くことも少なくない．進行度により予後や生活の質（QOL）が大きく左右されるため，早期かつ的確な診断が極めて重要である．本稿では，腺癌・扁平上皮癌をはじめとする多彩な症例を通じて，肛門鏡，内視鏡，肉眼所見を組み合わせた実際の診断手法と，その際に生じやすいピットフォールを解説した．近年の内視鏡観察技術の進歩により，順視・反転観察の併用やNBI拡大観察，麻酔下診察などを適切に活用することで，肛門管腫瘍の早期診断と見逃し防止が可能となっている．

　Anal canal cancers can closely resemble benign conditions such as hemorrhoids and anal fissures in their macroscopic appearance, frequently leading to diagnostic delays. Since the prognosis and quality of life（QOL）are greatly influenced by the stage at diagnosis, early and accurate detection is critically importance. In this article, we present a range of cases, including adenocarcinoma and squamous cell carcinoma, to illustrate practical diagnostic approaches that utilize a combination of anoscopic, endoscopic, and macroscopic visual findings. With recent advances in endoscopic techniques, the judicious use of both forward and retroflexed views, high-definition magnified narrow-band imaging（NBI）, and examination under anesthesia has significantly improved early diagnosis and reduced the likelihood of missed anal canal tumors.