早期胃癌切除標本の取り扱いと病理診断

Pathological Aspect of Early Gastric Carcinoma, Handling of the Endoscopically Mucosectomized Specimen and Problems in the Pathological Diagnosis

要旨　早期胃癌の治療は従来の胃切除術のほかに，内視鏡的粘膜切除が近年広く行われるようになってきている．切除胃の取り扱いは一般に胃癌取扱い規約により行われている．内視鏡的粘膜切除術も本来根治手術を目的としたものであり，その切除標本の取り扱いも根治性の判断が可能となるべく処置する必要がある．内視鏡所見とほぼ対応するように伸展・固定し，実体顕微鏡下に病巣の確認，カミソリによる細かい切り出しと，切除胃の“切り出し図”に対応する“切り出し写真”を撮影する．その具体例について示した．病理組織学的には癌との鑑別が問題となる小腸上皮型腺腫，再生異型との比較，診断の困難な腺窩上皮型癌，あるいは腸上皮化生に類似した癌の具体例を示し，生検診断の問題点を述べた．近年分子生物学が胃癌の診断にも応用され，これら境界領域病変に関して，あるいは胃癌の発生に関する研究が進行している．

　Early cancer of the stomach has had the majority in the resected gastric carcinoma. A surgically resected stomach is to be handled by“the general rules for gastric cancer study”, but there are differences in handling a resected specimen among institutes. Endoscopic mucosectomy is now widely performed on a small early carcinoma, especially, an elevated, type Ⅱa, less than 1 cm in size, and histologically well differentiated type lesion. As the procedure becomes common, its indication seems to expand. However, there is no general agreement of how to deal with a mucosectomized specimen. The objective of endoscopic mucosectomy is curative resection of early carcinoma. The resected specimen should be well fixed for the purpose of examining its margin and the depth of invasion to confirm the completeness of resection. We demonstrated how to fix and observe a specimen for stereomicroscopic examination using photographs.

　There are some pathological problems in diagnosing a gastric biopsy specimen. We showed photographs of the following lesions: an adenoma of small intestinal type and regenerative atypia which needed to be differentiated from a well differentiated adenocarcinoma; a well differentiated adenocarcinoma of foveolar epithelial type and a carcinoma mimicking intestinal metaplasia, which were difficult to diagnose. Molecular biological investigations on such lesions are in progress.