非乳頭部十二指腸浸潤癌の臨床病理学的・分子病理学的特徴

Clinicopathological and Molecular Characteristics of Non-ampullary Duodenal Carcinoma

要旨●非乳頭部十二指腸癌外科的切除例44例の臨床病理学的・分子病理学的特徴を発生部位別に検討し，それらの組織発生・発癌機序を考察した．Vater乳頭の口側発生癌は肛門側発生癌に比べ，胃型の粘液形質を呈するものが多く，GNAS，KRAS変異の存在から前駆病変として胃腺窩上皮化生や胃型腺腫などが想定された．一方，Vater乳頭の肛門側発生癌では，CD10発現やKRAS変異の存在から大腸のadenoma-carcinoma sequenceと同様の発癌も想定された．十二指腸全体でみても大腸にみられるserrated neoplasia pathwayをたどるものは極めてまれと考えられた．また，十二指腸は部位によりBrunner腺の存在による構造的特徴が異なるため，癌の組織発生や発癌機序も異なる可能性がある．非乳頭部十二指腸癌の組織発生の検討には，発生部位を分けた解析が必須と考えられる．

　The present study investigated the clinicopathological and molecular characteristics of 44 surgically resected cases of non-ampullary duodenal carcinoma, focusing on the onset site. Most duodenal carcinomas occurring on the oral side of the papilla of Vater exhibited a gastric phenotype, and the presence of GNAS and KRAS mutations suggested that the precursor lesions were gastric foveolar metaplasia and gastric adenoma. Contrarily, the CD10 expression and KRAS mutation indicated that the duodenal carcinomas occurring on the anal side of the papilla of Vater may have developed similar to the adenoma-carcinoma sequence in the large intestine. Moreover, the cases with the serrated neoplasia pathway seen in the large intestine were considered extremely rare. Given that the structural characteristics of the duodenum differ depending on the site due to the presence of the Brunner's glands, the main mechanisms of histogenesis and carcinogenesis of the carcinoma may also vary ; thus, it is essential to examine the histogenesis of non-ampullary duodenal carcinomas occurring in different sites.