癌粘膜内進展範囲の診断に難渋した早期胃癌の1例

Early Gastric Cancer in which the Diagnosis was Difficult Due to the Intramucosal Extension of the Lesion, Report of a Case

要旨　患者は54歳，男性．1996年7月，胃集団検診にて前庭部の透亮像を指摘され当センターを受診した．胃内視鏡では前庭部にびらん性変化が認められたが，生検では悪性所見は認められず，以後逐年で内視鏡での経過観察を行っていた．2000年6月の内視鏡検査で体中部後壁に褪色調の粘膜不整像を認め，生検にて印環細胞癌と診断された．胃X線検査では体部後壁を中心に不整なバリウム斑と顆粒像とを認めた．精査の胃内視鏡では体中部後壁に，通常観察ではやや褪色調のほぼ平坦な粘膜不整像を認め，色素撒布像では色素をはじく局面として認められた．以上の所見から0Ⅱc，T1(M)の未分化型癌と診断した．病理組織学的には，Type OⅡc，pT1(SM2)，大きさ9.0×7.5cmであり，組織型signet-ring cell carcinoma，INFγ，ly2，vO，pN0と診断された．病変は術前に診断した癌進展範囲よりも広く，非癌粘膜に被覆され粘膜固有層内を癌が進展した部分が認められた．術前の癌粘膜内進展範囲の決定が困難であった早期胃癌症例について，術後の臨床病理学的検討を含めて報告した．

　In July, 1996, a 54-year-old male patient was referred to our center for mass screening. A radiolucent lesion was diagnosed in the antrum. Endoscopical examination showed multiple erosions in the antrum for which the patient had been followed up endoscopically each year until 2000. In June of the same year, the follow-up by endoscopy showed a discoloured area in the posterior wall of the middle gastric body. Histological diagnosis confirmed a signet-ring cell carcinoma. Double contrast study showed a barium fleck and nodular mucosa in the posterior wall of the middle gastric body. The endoscopical examination showed a discoloured area and irregular mucosa in the same area. Indigo dye spray showed that the contrast surrounded the lesion. This kind of lesion is diagnosed as an undifferentiated type of early gastric cancer for which the patient underwent a subtotal gastrectomy. The histological diagnosis was 0 IIc, the size of the lesion was 9.0×7.5 cm, and the depth of invasion was SM2. The histological type was a signet-ring cell carcinoma, INFγ, ly2, v0, n0. The histological examination showed that the cancer was neither found in the surface of the mucosa nor did it invade the muscularis mucosae but was concentrated in the middle of the mucosal layer. Therefore it was difficult to diagnose the extension of the lesion before surgery.