胃IIb型癌の病理組織学的特徴―胃IIb型癌のマクロ像と組織像の対比

Histopathologic Feature of the IIb Type Gastric Cancer: Comparison between Macroscopic Findings and Histological Findings of the IIb Type Gastric Cancer

要旨　腫瘍径5mm以下の微小癌を除く早期胃癌655病変（M癌393病変，SM癌262病変）を対象として本研究を行った．純粋IIb癌は10病変（1.5％）で，随伴IIb癌は41病変（6.3％）であった．随伴IIb癌を伴うリスクの高い早期胃癌の特徴は，肉眼型は陥凹型で，組織型は未分化型および混合型で，癌巣周囲粘膜が噴門腺領域および中間帯～幽門腺領域，であった．約90％の随伴IIb癌は主病巣の横軸方向（側方）にIIb癌巣が存在していた．IIb面を構成する癌は組織学的にNT-porsig型，LS-tub2型，LG-tub1型の3群に分類可能であった．IIb面のマクロ所見の特徴はNT-porsig型では褪色，胃小区不明瞭化・消失であった．LS-tub2型では褪色あるいは発赤，胃小区不明瞭化・消失であった．LG-tub1型では発赤，胃小区明瞭化，胃小区粗大化であった．光沢感消失は，組織型を問わず高頻度で認められた．

　We investigated 655 early gastric cancer lesions except the minute cancer（393 intramucosal cancer lesions, 262 submucosally invasive cancer lesions）in this study. 10 lesions（1.5%）were diagnosed as pure IIb cancer, and 41 lesions（6.3%）were diagnosed as accompanying IIb cancer. The characteristic histopathologic findings of the high-risk cancer with the accompanying IIb lesion were“depressed type of macroscopic type”,“undifferentiated type or mixed type of histological type”,“cardiac gland region or intermediate zone～pyloric gland region of surrounding mucosa”. The accompanying IIb lesion existed in the lateral direction of the main tumor at a frequency of approximately 90%. The accompanying IIb cancers were classified histologically in the following three groups of NT- porsig type, LS-tub2 type, LG-tub1 type. The characteristic macroscopic findings of the NT-porsig type were“discolored”and“obscurity of the gastric area”. The characteristic macroscopic findings of LS-tub2 type were“discolored or redness”,“obscurity of the gastric area”. The characteristic macroscopic findings of the LG-tub1 type were“redness”,“obviousness of the gastric area”. “Disappearance of luster”was found in high frequency regardless of histologic type.