胎児消化管類似癌の内視鏡的特徴

Endoscopic Diagnosis of Adenocarcinoma with Enteroblastic Differentiation

要旨●胎児消化管類似癌（ACED）の早期病変の内視鏡診断について，臨床病理学的特徴を含めて検討をした．今回，当院で早期胃癌に対してESDを施行し，病理組織学的に少なくとも一部にACEDを含む癌14例を対象とした．ACEDの早期病変は粘膜下層浸潤，脈管侵襲陽性率が高く，高悪性度の腫瘍であった．白色光観察では全例が発赤調であり，12例が0-IIc型を呈し，そのうち5例は辺縁隆起を伴っていた．MESDA-Gでは全例を癌と診断することが可能であり，NBI併用拡大観察ではLBC（81.8%）とWOS（72.7%）が高率に観察されたが，内視鏡所見でACEDと一般型胃癌の鑑別は困難であった．さらに，ACEDの早期病変は通常の粘膜下層深部浸潤の内視鏡的特徴に乏しいにもかかわらず粘膜下層深部浸潤が多く，深達度診断も困難であった．以上より，ACEDの早期病変は高悪性度の腫瘍であるが，内視鏡的に質的診断・深達度診断が困難な病変であり，臨床病理学的特徴を理解したうえで診療にあたる必要がある．

　We reported the endoscopic features of ACED（adenocarcinomas with enteroblastic differentiation）based on their clinicopathologic features. We analyzed 14 lesions that were resected with ESD（endoscopic submucosal dissection）at our hospital and histopathologically diagnosed as ACED. As per previous reports, ACED demonstrated high levels of submucosal and lymphovascular invasion, indicating high malignancy. On white light endoscopy, all lesions showed reddish color, and 12 lesions showed 0-IIc, 5 of which had marginal elevation. There was no association between the marginal elevation of the tumors and submucosal invasion, and the invasive depth of the lesions was difficult to diagnose. MESDA-G（magnifying endoscopy simple diagnostic algorithm for early gastric cancer）diagnosed all cases as cancer, but endoscopic findings made it difficult to distinguish ACED from conventional gastric carcinomas. In conclusion, although ACED is a highly malignant type of cancer, its depth of invasion and qualitative diagnosis are difficult to determine by endoscopy. Therefore, clinicopathological features of ACED should be considered by endoscopists and pathologists.