未分化型混在早期胃癌の臨床的特徴と問題点―X線診断を中心に

Clinicopathological Feature and Problems of the Histologically Mixed Type Early Gastric Cancer

要旨　未分化型混在早期胃癌48例についてX線診断を中心に臨床的特徴と問題点につき検討を行った．平均年齢は59.5歳（37～78歳），男女比は46：と男性に多く，病変の占居部位はU領域：6例，M領域：21例，L領域：21例，病変の存在する背景粘膜は胃底腺領域1例，中間帯領域27例，萎縮領域20例であった．①肉眼型は陥凹型が多く，隆起型を呈する症例では6例中4例が浸潤部にて未分化型が発現しており，粘膜内癌の2例は組織学的に胃型の分化型癌の症例であった．②基本的に優位な組織型に類似したX線所見を呈する．③分化型（tub1，tub2）優位の混在型においてporの混在は浸潤部での発現であることが多く，組織学的には分化型と未分化型は比較的境界を持って存在し，そのような症例のX線所見は比較的未分化型に類似した境界が明瞭な深い陥凹を呈することが多く，porの組織像が量的に少ない場合は線状の陰影斑を呈し，やや大きめの顆粒状構造が認められる傾向にあった．④sig優位の混在型においてはtub2の組織型との混合が多く，胃底腺領域内に発生したものはなかった．組織学的には同じ領域内での混在であり明瞭な境界を持ち組織型が分かれているものはなく，そのX線所見は比較的陰影斑は明瞭に描出されるが，典型的な未分化型癌のX線所見に比して陥凹面が浅く凹凸があまり目立たず微細～顆粒状粘膜を呈する傾向にあり，分化型との混合部分では境界が不明瞭になり，進展範囲がわかりにくいものであった．以上より未分化型混在早期胃癌の内視鏡治療を施行する際には臨床病理学的特徴を十分に理解し，術前の深達度診断，進展範囲診断を行う必要があると考えられた．

　To make clear the features and problems of early gastric carcinoma, histologically mixed type (differentiated type and undifferentiated type), we investigated 48 cases mainly by using x-ray diagnosis. The conclusion as follows:

　The mean age was 59.5 years (37～78). The male-female ratio was 46:2. The location was U:6 cases, M:21 cases, L:21 cases. For the background, 1 case was in the fundic gland, 27 cases were in the intermediate, and 20 cases in the atrophic gastric mucosa.

　(1) Macroscopic depressed type was predominant. In 4 of 6 elevated lesions, histologically undifferentiated characteristics appeared at the edge of invasion. The remaining 2 were within the mucosa, and were pathologically gastric type.

　(2) The x-ray findings were similar to the histologically predominant type.

　(3) In the histologically mixed type, mainly tub1 and tub2, histologically poorly differentiated type (por) appeared mostly at the edge of invasion. Thus, the histological borderline between differentiated and undifferentiated types is relatively clear. In such cases, an obvious depressed borderline often appeared, similar to the undifferentiated type. In the cases not containing enough poorly differentiated type, the appearance of the border tends to be shaggy.

　(4) In the histologically mixed type, mainly signet ring, containing tub2, none were in the fundic gland. The histologically borderline types were not clearly differentiated from the mixed type (tub1, tub2-por).

　Although the macroscopic borderline was relatively clear, depression was shallow and large granules were not seen.

　Especially in the mixed type, to discern the borderline of the lesion from the differentiated type was difficult.

　In carrying out endoscopic therapy for histologically mixed type early gastric carcinomas, we concluded that it was most important to understand the pathological features of the clinical manifestation in order to make decisions concerning the depth and range of the lesions.