Brunner腺：十二指腸の腫瘍様病変と腫瘍発生における役割

Brunner's Glands：Involvement in the Pathogenesis of Tumor-like Lesions and Duodenal Tumors

要旨●十二指腸の上皮性腫瘍を正しく診断するためには，十二指腸の特徴的な組織学的構築を知り，腫瘍様病変，良性腫瘍，さらに悪性腫瘍の成り立ちを組織発生の観点から理解しておくことが重要である．十二指腸の表面は空腸・回腸に連なる小腸型粘膜が被覆しているが，乳頭部辺りまでは粘膜下組織にBrunner腺が存在する．Brunner腺の一部は粘膜内にもみられ，小腸型陰窩底部に開孔する．Brunner腺は胃の粘液腺と同様の性質を持つ安定的な細胞であるが，自己再生能力があり，びらんや潰瘍によって胃腺窩上皮へ分化する．また，十二指腸粘膜やBrunner腺内には胃底腺型細胞（壁細胞は主細胞）もしばしば観察される．したがって，十二指腸上皮由来の腫瘍様病変や腫瘍には小腸型形質と胃型・Brunner腺形質あるいはそれらの混合型形質を持つものがある．Brunner腺に焦点を当て，十二指腸腫瘍の組織発生について論じる．

　Understanding the characteristic histological architecture of the duodenum and the pathogenesis of tumor-like lesions, benign tumors, and malignant tumors from histopathogenetic viewpoints is important for the correct diagnosis of duodenal epithelial tumorigenesis. The surface of the duodenum is covered with small intestinal-type mucosa connected to the jejunum and ileum, and Brunner's glands are present in the submucosa to the ampullary region. Some Brunner's glands are seen in the mucosa and at the base opening of small intestine crypts. Brunner's glands consist of stable cells with properties similar to those of pyloric glands in the stomach. However, these cells can self-renew and potentially differentiate into gastric foveolar epithelium by erosion or ulceration. In addition, gastric fundic gland cells（parietal and chief cells）are often observed in the duodenal mucosa and Brunner's glands. Therefore, the origin of tumor-like lesions and duodenal epithelial tumors may show a small intestinal phenotype, gastric-Brunner's glands phenotype, or mixed phenotype. We herein discuss the involvement of Brunner's glands in the tumorigenesis of duodenal epithelial lesions.