潰瘍合併早期胃癌の病理―切除標本からみた潰瘍合併早期胃癌

Pathological Characteristics of Early Gastric Cancer with Intratumoral Ulceration

要旨　内視鏡的粘膜下層剝離術（endoscopic submucosal dissection ; ESD）標本および手術標本を用いて，癌巣内潰瘍（UL）合併早期胃癌の病理学的特徴について検討した．ESD標本の検討では，生検痕による線維組織の拡がりは2.7mm以下であった．切除標本の検討では，真のULは粘膜筋板から固有筋層に向かって，線維組織が扇状に拡がる形態を示した．pT1a（M）症例において，粘膜内で分化型癌優位の病変は未分化型癌優位の病変よりも線維組織の拡がりが大きく，固有筋層まで線維組織が達する症例が多く，ESDの難易度が高いと考えられる病変が多かった．pT1b（SM）症例では，分化型癌優位病変の粘膜下層浸潤はULの線維組織外にみられ，線維組織内での癌浸潤は乏しい病変が多かった．一方，未分化癌優位の病変では線維組織内にびまん性浸潤を示す病変が多かった．UL合併早期胃癌にESDを行う場合，その病理学的特徴を熟知したうえで治療を行う必要がある．

　We analyzed the pathological features of EGC（early gastric cancer）with UL（ulceration in the cancer nest）. In the examination of ESD（endoscopic submucosal dissection）specimens, the extent of fibrous tissue by biopsy scar was less than 2.7mm. In the examination of surgical specimens, true UL's showed fan-shaped forms of fibrous tissue that extended toward the muscularis propria from the muscularis mucosae. In intramucosal EGC, the spread of the fibrous tissue of the differentiated-type was greater than that of the undifferentiated-type and many lesions showed that fibrous tissue reached the muscularis propria. So, it is considered that ESD for the differentiated-type is difficult. In EGC with submucosal invasion, the differentiated-type showed massive submucosal invasion outside the fibrous tissue, and poor infiltration within the fibrous tissue. On the other hand, many lesions of the undifferentiated-type revealed diffuse infiltration within the fibrous tissue. When performing ESD for EGC with UL, we should carry out the treatment while being well aware of the pathological features.