食道・噴門境界部の微小癌

Minute Early Carcinoma on the Esophago-gastric Junction

　病理組織学的に癌組織の広がりが長径1cm以内にとどまる早期胃癌を微小癌と定義すれば，現在までにかなり多くの症例が発見されている．今日ではすでに長径5mm以下のものすら診断されて，このようなものでなければ微小癌といえないとする人さえある．また微小癌に関するシンポジウムも学会ですでに2回にわたりもたれている¹⁾²⁾．しかし，これらはいずれも胃体中部から幽門部にかけての範囲に発生した微小癌についてであって，噴門部の微小癌の診断はやや立遅れたきらいがある．特に食道胃接合部に接した部位に発見された微小癌の症例は，この部位の診断上の特殊性もあり，あまり見当たらない．

　近年前方直視式のいわゆるPanendoscope型のファイバースコープが普及し，この食道胃接合部の観察も多くの人々に容易となってきた．このような現状から，われわれの食道胃接合部上ないしはこれに接した微小癌の症例を提示しつつ，この部位の微小癌の特徴，診断上の問題点等をさぐってみたい．

　Diagnosis of minute lesions near the esophagogastric junction has been considered to be difficult. In fact, minute early cancer less than 1 cm in the longest diameter has rarely been reported. Most of cancer cases in this area are too much advanced to undergo surgical resection. In this paper are demonstrated in detail three cases of minute cancer in the esophagogastric junction. Their macroscopic, microscopic characteristics, their diagnosis and diagnostic problems are also analyzed here.

　All of them revealed well differentiated adenocarcinoma of Ⅱa type. Their size was 0.5×0.4, 1.0×0.7, 0.9×0.5 cm, respectively. The diagnosis was confirmed by a forward viewing panendoscope and biopsy.

　So far only a single case of such minute cancer in this junction has been described in Japan, while early cancer of the same site less than 2 cm in diameter has already been diagnosed in 6 cases. Nine out of 10 cases including our three cases revealed the elevated type of early cancer except for 1 case of IIb. This fact seems to suggest that this elevated appearance is a special characteristics of such small early cancer near the squamo-columnar junction.

　For X-ray diagnosis of small lesions in this part it is most valuable to catch abnormal barium streams from the esophagus to cardia. For endoscopic diagnosis, forward viewing fiberscope must be selected and the junction should be observed dynamically with accurate biopsy. Finally, it is emphasized that better understanding of the lesions in this area is essential for gastroenterologists as is untiring effort to diagnose them.