非乳頭部十二指腸の上皮性腫瘍および腫瘍様病変の病理組織学的特徴

Histopathological Features of the Epithelial Tumors and Tumor-like Lesions of the Non-papillary Duodenum

要旨●非乳頭部十二指腸の上皮性腫瘍および腫瘍様病変には，腺腫，腺癌，神経内分泌腫瘍，異所性胃粘膜，腺窩上皮過形成性ポリープ，Brunner腺過形成，粘膜下腫瘍様病変，Peutz-Jeghersポリープ（過誤腫性ポリープ）などがある．近年，十二指腸病変に遭遇する機会が増え，典型的病変以外に複雑な病理組織像を示す病変に遭遇することも多くなっている．特に腫瘍性病変に関しては，小腸型腺腫や幽門腺腺腫に加え，胃腸混合型腺腫や胃底腺への分化を伴う腫瘍，鋸歯状病変，絨毛腫瘍など多彩であり，それぞれにおいて癌の併存するものも存在する．それらの鑑別診断においては，各病変の病理組織像を細胞分化と組織構築の特徴と合わせて理解する必要があり，形質発現や増殖細胞の分布の評価が有用である．

　The epithelial tumors and tumor-like lesions of the non-papillary duodenum include adenomas, adenocarcinomas, neuroendocrine tumors, heterotopic gastric mucosa, foveolar hyperplastic polyps, Brunner's gland hyperplasia, submucosal tumor-like lesions, Peutz-Jeghers polyps, and hamartomatous polyps. Recently, the occurrence of typical duodenal lesions and those with complex histology have increased. In particular, regarding the neoplastic lesions, in addition to small intestinal type and pyloric adenoma, there are wide variety of gastrointestinal mixed-type adenomas, including tumors differentiating into fundic glands, serrated lesions, and villous tumors. Moreover, the lesions coexist with cancer.

　Therefore, it is necessary to understand the histological features of each lesion, characteristics of cell differentiation and histologic architecture, and evaluate the phenotypic expression and distribution of proliferating cells for the differential diagnosis of these lesions.