粘膜下腫瘍様形態を示す胃癌の臨床病理学的特徴

Pathological Studies of Gastric Carcinoma Resembling Submucosal Tumor

要旨　粘膜下腫瘍様形態を示した胃癌（SMT様癌）について臨床病理学的・組織学的な検討を行い，その特徴を粘膜下腫瘍（SMT）と対比して検討し，更に文献的な検討を行った．その結果，SMT様癌は，組織学的に，①por1（endocrine cell carcinomaを含む）とcarcinoma with lymphoid stromaの群，②組織型にかかわらずリンパ球浸潤の強い群，③癌巣周辺に限局した線維化を認める群，④粘液癌，⑤粘膜下異所性腺からの発生が考えられる群，⑥その他，に分類できた．またSMT様癌の成り立ちは，腫瘍自体が粘膜下で膨張性に増殖する型と，腫瘍周辺の反応性変化のために膨張性の病変となるものに分類できた．SMT様癌は，SMTと比較して，占居部位はA領域に多く，高さが低く，隆起の基部が不整で，陥凹面が大きく不整で浅いものが多く，比較的深いものでは内掘れ傾向があるものが多かった．

　A Study aimed as comparing pathologic findings in 12 cases of adenocarcinomas resembling submucosal tumors (SMT-like carcinoma; SMTC) with findings in 29 cases of submucosal tumors (SMT) such as leiomyoma, heterotopic pancreas or neurogenic tumors, and to detect pathologic features by which SMTC can be distinguished from those of SMT.

　Statistically, significant differences were found between SMTC and SMT in the ratios of height to width of the tumors, of size of craters to size of tumor, and of depth to width of craters. Histologically, 12 SMTC were divided into five types; 1) poorly solid carcinomas including neuroendocrine carcinomas and carcinomas with lymphoid stroma, 2) carcinomas with massive lymphocytic infiltration irrespective of histologic types, 3) carcinomas with marked fibrosis around the tumors, 4) mucinous carcinomas, 5) carcinomas arising from heterotopic glands, and 6) other types. The elevation of SMTC appeared to be able to be ascribed to the occurrence of fibrous accumulation due to excessive submucosal fibrosis, massive lymphoid infiltration, submucosal heterotopic glands or mucinous adenocarcinoma with mucous lake.

　In comparison with SMT, SMTC tended to arise in the A-area, to have a lower height with an irregular circumferential margin of the elevated part of the tumor, to have larger, shallow craters with irregular margins. The craters of SMTC, when deeply excavated, tended to have concave inner walls.