拡大内視鏡観察からみた微小胃癌の臨床診断の限界

Limitation in the Diagnosis of Minute Gastric Cancers in the Endoscopic Observation Using Magnifying Endoscopes

要旨　点または線状に陥凹した胃小窩単位の模様像を観察する拡大内視鏡観察の微小胃癌診断での有用性と限界について，診断困難であった微小・小胃癌4症例の拡大内視鏡所見を提示すると共に，内視鏡的粘膜切除術で治療された微小胃癌34病変と組織学的に診断された微小胃癌113病変を検討し考察を加えた．結論として，微小胃癌の拡大内視鏡観察では，腺管密度が高い大半の高分化管状腺癌においては有用であるが，構造異型に乏しい高～中分化型癌や腺管構造の異常を伴わない低分化腺癌，印環細胞癌の正確な診断は困難と思われた．すなわち，診断が容易な症例のみ発見しているのが，微小胃癌の拡大内視鏡を含む内視鏡診断の限界と考えた．

　Magnifying endoscopy of gastric mucosa is considered as diagnostic endoscopic system used to observe various changes occurring in the fine gastric mucosal pattern consisting of gastric pits. In this study, usefulness and limitation of the endoscopic diagnosis of minute gastric cancers using magnifying endoscopes are discussed from; our experience in magnifying endoscopy three cases of minute type Ⅱc and one case of small type Ⅱb gastric cancer which are difficult to diagnose; re-evaluation of the process of endoscopic diagnosis of 34 cases of minute gastric cancers treated by endoscopic mucosal resection; and an investigation of 113 cases of minute gastric cancers diagnosed histologically in surgically resected stomachs.

　As result, in the endoscopic diagnosis of minute gastric cancers, well differentiated carcinoma which showed dense and irregular tubular structures were easy to diagnose by confirming the characteristic pit patterns finer than the surrounding mucosa. On the other hand, well to moderately differentiated tubular adenocarcinoma lesions without distinct abnormality of tubular structure, and signet-ring cell carcinoma and poorly differentiated adenocarcinoma without destruction of mucosa were difficult to diagnose even with magnifying endoscopes. In conclusion, it is considered that the usefulness of magnifying endoscopy in the diagnosis of minute gastric cancer is limited to the lesions which are easy to diagnose.