十二指腸の腫瘍・腫瘍様病変の病理診断―腫瘍様上皮性病変とそれら由来の腫瘍の病理学的特徴

The Pathological Diagnosis of Tumors and Tumor-like Lesions in the Duodenum

要旨　十二指腸は小腸の一部に区分され粘膜は絨毛と陰窩から成るが，深部に存在するBrunner腺によって特徴づけられる．また，乳頭部には胆道系上皮が突出している．胃粘膜に腸上皮化生がみられるのとは対照的に，十二指腸には胃腺窩上皮化生がしばしば認められ，その発生にはBrunner腺の再生が関連しており，病態を複雑にしている．十二指腸の上皮性腫瘍様病変としては，Brunner腺過形成・過誤腫，異所性胃粘膜，Peutz-Jeghers polypや異所性膵などが知られている．十二指腸の上皮性腫瘍には小腸型形質のみならず，胃型形質を示すものが多いのは，胃上皮化生やこれらの腫瘍様病変がその発生に深く関与しているからである．

　The duodenum is a part of the small intestine, the mucosa of which is composed of villi and crypts. The duodenal mucosa is characterized by Brunner's glands and biliary duct epithelium at the major and minor duodenal papillae. In contrast to gastric mucosa showing intestinal metaplasia, duodenal mucosa sometimes shows gastric metaplasia. The regeneration of Brunner's glands is closely related to the development of gastric metaplasia, which makes understanding of duodenal mucosa more difficult. Brunner's gland hyperplasia/hamartoma, heterotopic gastric mucosa, Peutz-Jeghers polyp and heterotopic pancreas are well-known as tumor-like lesions of the duodenum. The reason why many duodenal tumors show gastric phenotype in addition to intestinal phenotype is that these tumor-like lesions and gastric metaplasia are closely related to the development of duodenal tumors.