腺窩上皮型腫瘍の新展開—腺窩上皮型胃腫瘍の内視鏡診断

Endoscopic and Pathologic Features of Foveolar-type Gastric Neoplasm

要旨●H. pylori未感染者に発生するラズベリー様腺窩上皮型胃腫瘍とH. pylori既感染者に発生する腺窩上皮型胃癌の臨床病理学的特徴を検討した．前者は萎縮のない胃底腺領域に発生する発赤小隆起で，いわゆるラズベリー様外観を呈し，NBI拡大観察で不整な乳頭状/脳回様構造を呈した．後者は萎縮粘膜に発生する粗大な発赤隆起で，前者より大きく形態も歪であった．NBI拡大観察で乳頭状/脳回様構造を呈したが，形態不整は高度であった．病理組織学的には，前者はよく分化した上皮内病変で，WHO分類では多くがlow-grade dysplasia相当であったが，Ki-67 labeling indexは異型度によらず高値を示した．後者は構造異型・細胞異型が高度で，脱分化や脈管侵襲も認められ，胃型胃癌としての高い悪性度を示した．

　We analyzed the clinicopathological characteristics of foveolar-type gastric neoplasm in H. pylori（Helicobacter pylori）-naïve and H. pylori-infected patients. The naïve patients showed raspberry-like small polyps in the non-atrophic oxyntic gastric compartment on white-light endoscopy. NBI-ME（narrow band imaging with magnification endoscopy）revealed irregularly shaped papillary/gyrus-like microstructures. The infected patients demonstrated larger and more irregular protruded forms than the naïve patients. NBI-ME revealed the presence of highly irregular papillary/gyrus-like microstructures. Histologically, the naïve patients possessed an intraepithelial lesion and predominantly corresponded to low-grade dysplasia as per the World Health Organization classification. However, regardless of the histologic atypical grade, Ki-67 was overexpressed in the lower and middle layers of the neoplasm. The infected patients exhibited severe architectural and cellular atypia, and some showed cellular de-differentiation and lymphovascular invasion.