胃型形質を示す非乳頭部十二指腸腺腫・癌の臨床病理学的特徴

Clinicopathological Characteristics of Non-ampullary Duodenal Adenoma and Adenocarcinoma Showing Gastric Type Characteristics

要旨●当科で内視鏡的ないし外科的切除により病理組織学的に非乳頭部十二指腸腺腫・癌と確定診断された85例94病変のうち胃型形質と診断された32例35病変を対象とし，その臨床病理学的特徴を遡及的に検討した．32例35病変の平均年齢は72.2歳で，男性25例，女性7例であった．35病変は十二指腸球部25病変（71.4%），下行部乳頭口側6病変（17.1%）と乳頭より近位側の十二指腸に好発し．肉眼型はSMT様隆起が20病変（57.1%），0-I型が14病変（40.0%）と丈の高い病変がほとんどであった．白色化は35病変中6病変（17.1%）に認めるのみであった．術前に生検を施行した26病変のなかで評価可能であった25病変中22病変（88.0%）で病理組織学的に胃型腫瘍の可能性が示唆されていた．切除標本を検討すると病理組織学的に病変表面には胃腺窩上皮への分化を示す細胞から成る領域を35病変中34病変（97.1%）に認めた．35病変は病理組織学的に腺腫26病変，NUMP（neoplasms of uncertain malignant potential）3病変，腺癌6病変に分類された．NBI併用拡大観察では，NUMPと癌は，腺腫と比較してirregular MS pattern, irregular MV patternをそれぞれより高頻度に認めた．腺癌は全例，高分化管状腺癌で，M癌2例，SM癌4例であった．35病変は優位形質から分類すると，MUC5AC優位型（foveolar type）15病変（腺腫13病変，NUMP 2病変），MUC6優位型（pyloric gland type）18病変（腺腫13病変，NUMP 1病変，腺癌4病変）と分類不能型2病変（腺癌2病変）に分類された．MUC6優位型でより高頻度にSMT様の形態を呈していた．

　We retrospectively reviewed the clinicopathological features of 35 lesions of 32 patients who were diagnosed as having gastric type characteristics among 94 lesions of 85 patients histopathologically confirmed as non-ampullary duodenal adenoma and carcinoma by endoscopic or surgical resection in our department. The mean age of the 35 lesions of 32 cases was 72.2 years, with 25 males and 7 females. Of the 35 lesions, 25（71.4%）were of the duodenal bulb, 6（17.1%）in the oral side of the descending papilla, i.e., in the duodenum proximal to the papilla. The macroscopic type was SMT（submucosal tumor）-like elevation in 20 lesions（57.1%）and 0-I type in 14 lesions（40.0%）. Whitening was observed in only 6 of 35 lesions（17.1%）. Of the 26 lesions biopsied preoperatively, 22 of the 25 lesions（88.0%）that were evaluable were histopathologically suggestive of possible gastric-type tumors. Histopathologically, 34 out of 35 lesions（97.1%）were composed of cells differentiated into the crypt epithelium. The 35 lesions were histopathologically classified into 26 adenomas, 3 NUMP（neoplasms of uncertain malignant potential）and 6 adenocarcinomas. In the extended observation with NBI（narrow band imaging）, NUMP and carcinoma showed more frequent irregular MS pattern and irregular MV pattern, respectively, compared with adenoma. Adenocarcinomas were all well-differentiated adenocarcinomas, 2 were M carcinomas and 4 were SM carcinomas. Thirty-five cases were classified into 15 MUC（mucin）5AC predominant（foveolar type）（13 adenomas, 2 NUMP lesions）, 18 MUC6 predominant（pyloric gland type）adenomas（13 adenomas, 1 NUMP lesion, 4 adenocarcinomas）, and 2 non-classifiable adenocarcinomas（2 adenomas）. SMT-like morphology was shown to occur at a higher frequency in MUC6-predominant lesions.