外科切除例からみた表在Barrett食道癌の進展範囲と深達度診断

Macroscopic Diagnosis of the Extension and the Depth of Cancer Invasion of Superficial Barrett's Adenocarcinoma

要旨　外科切除表在Barrett食道癌5例を用いて，同癌の進展範囲と深達度診断について検討・考察した．粘膜内癌は，新生粘膜筋板までにとどまるものをm1，同粘膜筋板を越えて食道固有の粘膜筋板までにとどまるものをm2に，細分類した．m1癌は平坦，色調も周囲粘膜とほぼ同色調で，表面性状の変化にも乏しく，肉眼存在診断自体が困難であった．m2癌からは凹凸が出現し，褐色調，分葉状，微細絨毛状，顆粒・結節状などの表面性状から，存在診断・進展範囲診断が可能であった．m2癌の進展範囲診断では，癌が扁平上皮下を潜り広範囲に拡がっている可能性を常に念頭に置く必要がある．癌sm浸潤部は，①褐色調の色調が強い，②隆起，③表面光沢感の減少と平滑化，の3点でm2癌との識別が可能であったが，深い陥凹，びらん，潰瘍などの粘膜模様消失像を呈したものはなかった．これは，癌組織型が，smに浸潤しても粘膜内癌部の脱落を来すことの少ない，乳頭状癌や低異型度癌であったことに起因していた．m2癌の中には，sm大量浸潤癌と類似した肉眼形態を示すものがあった．内視鏡的治療を念頭に置いた表在Barrett食道癌の深達度診断を考える上で，こうした肉眼形態がm2癌の発育進展過程にとって一般的なものかどうかを明らかにすることが今後の重要な課題である．

　Five cases of superficial Barrett's adenocarcinoma surgically resected were examined macroscopically and histologically for the macroscopic diagnosis of their extension and the depth of cancer invasion. Intramucosal carcinoma was divided into m1; in which the carcinoma was limited to within the newly generated muscularis mucosae, and m2; in which the carcinoma extended beyond the newly generated muscularis mucosae but not beyond the proper muscularis mucosae of the esophagus. Macroscopic diagnosis of the m1 cancers was almost impossible because they were flat and showed no change in either color or surface appearance as compared to the surrounding non-neoplastic mucosa. The m2 cancers can be detected and their extension margin can be determined macroscopically because of their convexo-concave appearance, brownish color and lobular, fine villous, granular, nodular surface appearance. To determine the extension margin of the cancer, one should take into consideration the possibility that the cancer may extend widely beneath the squamous epithelium of the esophagus. Submucosal invasion of such cancers can be detected by their (1) markedly brownish color, (2) elevation, and (3) loss of transparency and of the surface appearance. They presented neither deep depression, erosion, and/or ulceration, which factors represent the destruction of the mucosal component. It is explained by the fact that their histology is papillary and/or low-grade atypia. Some m2 cancers showed a macroscopic appearance reminiscent of cancer with massive submucosal invasion. To establish a macroscopic (endoscopic) diagnosis system of the depth of cancer invasion which is essential for endoscopic treatment of Barrett's adenocarcinoma, it is considered important to elucidate whether or not such macroscopic appearance would be a general form of m2 cancers during their development and growth.

　1) Division of Molecular and Diagnostic Pathology, Gradulate School of Medical and Dental Sciences, Niigata University, Niigata, Japan

　2) Division of Molecular and Functional Pathology, Gradulate School of Medical and Dental Sciences, Niigata University, Niigata, Japan

　3) Emeritus Professor, Niigata University, Niigata, Japan