胃MALTリンパ腫—胃癌との鑑別点を中心に

Gastric MALT Lymphoma：Points to Differentiate from Gastric Cancer

要旨●胃MALTリンパ腫は多彩な内視鏡像を呈し，胃癌との鑑別が困難となる場合がある．特に未分化型早期胃癌（0-IIc型）および胃底腺型腺癌は，MALTリンパ腫と類似した所見を示すことがある．未分化型早期胃癌との鑑別では，腫瘍境界の所見および蚕食像の有無を評価することが有用である．一方，胃底腺型腺癌との鑑別では，病変の大きさや分布の違いが参考となる．さらに，MALTリンパ腫は多発病変を認めることが多いが，胃癌は主に単発病変である．拡大観察における特徴的な血管構造（tree-like appearance）も重要である．本稿では，胃MALTリンパ腫の内視鏡像と病理組織学的診断の要点について，胃癌との鑑別を中心に解説する．

　Gastric MALT（mucosa-associated lymphoid tissue）lymphoma has various presentations on endoscopic images, sometimes making it difficult to differentiate from gastric cancer. In particular, undifferentiated-type early-stage gastric cancer and adenocarcinoma of the fundic gland type show signs similar to those of gastric MALT lymphoma. To differentiate from undifferentiated-type early-stage gastric cancer, findings on the tumor border and the presence or absence of encroachment should be evaluated. In contrast, to differentiate from adenocarcinoma of fundic gland type, gastric MALT lymphoma exhibits differences in lesion size and distribution. Furthermore, MALT lymphoma often exhibits multiple lesions within the stomach, whereas gastric cancer is primarily solitary. In addition, a characteristic vascular structure（tree-like appearance）in magnified observation is also an important point for differentiation. In this article, we describe the endoscopic images and discuss key points in the pathological diagnosis of gastric MALT lymphoma, focusing on its differentiation from gastric cancer.