微小胃癌の拡大内視鏡診断の限界に迫る―未分化型微小胃癌の診断

Diagnosis of Undifferentiated Micro Gastric Cancer Using Magnified Endoscopy with Narrow Band Imaging

要旨　2005年4月～2012年10月までに，当院でESDが施行された未分化型癌のうち，5mm以下の微小胃癌43症例45病変と小胃癌53症例54病変を比較し，微小胃癌45病変のNBI拡大内視鏡像と病理組織像との対比について検討した．SM癌は，微小胃癌で2例（4.4％），小胃癌では7例（13％）にみられた．組織像は，微小胃癌でsigの割合が高く42例（93.3％），porは3例（6.7％），小胃癌ではsigが39例（72.2％），porは15例（27.8％）であった．肉眼型は，微小胃癌で0-IIb型11例（24.4％），0-IIc型34例（75.6％），小胃癌で0-IIb型4例（7.4％），0-IIc型50例（92.6％）で，微小胃癌で0-IIb型の割合が高かった．微小胃癌の検討では，NBI拡大内視鏡像で明らかな血管パターンの異常がなく，窩間部開大のみのものをS Type，血管パターンに異常があるものをV Typeとした．組織像では，粘膜内の癌の浸潤程度で全層，中～上層，中層，上層に分類した．窩間部開大を示し，異常血管の所見がないS Typeが23例，血管パターンに異常がみられたV Typeが22例であった．V Typeを呈した22例中17例（77.3％）で，全層もしくは中～上層に癌の発育がみられた．S Typeは23例で中層にのみ限局したものが23例中14例（61.0％）にみられた．病変範囲のonline markingは6症例，9ポイントに行われ，5/9ポイント（55.6％）が正診されていた．

　We carried out a comparative investigation of 45 lesions（from 43 patients）of micro gastric cancer, measuring less than 5mm in diameter, and 54 lesions（from 53 patients）of small gastric cancer among patients with undifferentiated cancer who received ESD（endoscopic submucosal dissection）at this hospital between April 2005 and October 2012, and also comparative evaluation of the NBI（narrow band imaging）magnifying endoscopic images and histopathological findings of the 45 lesions of micro gastric cancer. SM cancer was observed in 2 cases of micro gastric cancer（4.4％）, and 7 cases of small gastric cancer（13％）. In regard to the histopathological findings, the percentage of sig was higher among the cases of micro gastric cancer（42cases ; 93.3％）, with 3cases of por（6.7％）, while, among the cases of small gastric cancer, there were 39cases of sig（72.2％）and 15cases of por（27.8％）. The macroscopic morphological type among the cases of micro gastric cancer was 0-IIb in 11cases（24.4％）and 0-IIc in 34cases（75.6％）, while that among the cases of small gastric cancer was 0-IIb in 4cases（7.4％）and 0-IIc in 50cases（92.6％）; thus, the percentage of the 0-IIb type was higher among the patients with micro gastric cancer. In the study of micro gastric cancer, the type showing no apparent abnormal vascular pattern, but only enlargement of the intervening part in magnifying NBI images was classified as the S-type and the type showing abnormality of the vascular pattern was classified as the V-type. Histopathological images were classified into whole-layer, middle-upper layer, upper layer and middle-layer depending on the degree of invasion of the submucosa by the cancer. There were 23cases of the S-type showing enlargement of the intervening part and no abnormal vascular finding and 22cases of the V-type showing abnormality of the vascular pattern. In 17 of the 22cases of the V-type（77.3％）, the depth of invasion of the cancer was classified as the whole-layer or middle-upper layer type. As for the S-type, cancer limited to the middle layer was observed in 14 of the 23cases（61％）. Online markings of the extent of the lesion were performed for 9 points in 6cases, and 5 out of the 9 points（55.6％）were diagnosed properly.