—胃型形質を示す胃上皮性腫瘍の内視鏡的特徴—胃型腺癌

Gastric Carcinoma with the Gastric Mucin Phenotype

要旨●胃型の粘液形質を呈する分化型癌で腺窩上皮型腫瘍，胃底腺型腫瘍，胃粘膜型腫瘍，胃型腺腫の特徴を有さない，いわゆる“その他の胃型分化型癌”の臨床病理学的・内視鏡的特徴を検討した．対象となる病変は免疫組織化学的検討結果と組織学的構築像より，①腺窩上皮類似型（表層型），②胃固有粘膜類似型（粘膜型），③腸上皮化生類似型，の3つのカテゴリーに分類可能であった．腺窩上皮類似型では，隆起性病変で表層が乳頭状から顆粒状構造を呈することが多く，固有粘膜類似型は発赤調で病変周囲に同色調の辺縁隆起がみられることが多かった．腸上皮化生類似型は胃腸混合型の占める割合が高く，腸型病変の特徴と類似していた．胃腸混合型は胃型優位であっても形態学的には腸型に分類するのが妥当と思われた．今回の対象となる胃癌は多様性に富む雑多な集団であり，それぞれの分類にも移行性があり内視鏡像は多彩である．胃型の粘液形質を呈する分化型癌は今後さらに臨床的重要度が増すと見込まれ，さらなる多数例での検討で臨床的特徴を明らかにすることが望ましい．

　We analyzed clinicopathological and endoscopic characteristics of gastric carcinoma with the gastric mucin phenotype. Foveolar- type gastric neoplasm, gastric-type adenoma-associated adenocarcinoma, and fundic-type adenocarcinoma were excluded from the study.

　Immunohistochemical and histological analyses were performed to classify the lesions into the following categories：1） foveolar-like type（superficial type）, 2） gastric proper mucosa-like type（mucosal type）, and 3） intestinal metaplasia-like type.

　Foveolar-like type lesions were frequently elevated, and the superficial structure was often papillary to granular. Gastric proper mucosa-like type lesions were mostly reddish and had normal-colored mucosal elevations at the edge of the lesions. All intestinal metaplasia- like type lesions were of gastrointestinal phenotype, and their characteristics were similar to the intestinal phenotype. Morphologically, the gastrointestinal phenotype should be classified as an intestinal phenotype, despite its dominance in the lesion. The lesions evaluated in this study were diverse and heterogeneous, and their endoscopic images were also extremely diverse.

　In the near future, differentiated carcinomas with gastric mucin phenotypes are expected to become more clinically relevant. Thus, a multicenter study is needed to evaluate a large number of lesions to further clarify their clinical characteristics.