胃良性リンパ腫の内視鏡診断

Endoscopic Diagnosis of Benign Lymphoma of the Stomach

　本病変が，主として粘膜上皮下層のリンパ系および網内系細胞の増生によるものである以上，胃粘膜の表面にあらわれた肉眼的変化をとらえようとする内視鏡的手段でその変化を的確に表現することは大変難しいことであり，病理組織学的にも良性，悪性の鑑別に困難を極める例があるというのに，肉眼的にその鑑別を試みることは，至難の業と考えていた．しかしながら，lymphoreticular tissueの増生が著しい場合に，胃粘膜にも肉眼的な変化があらわれ，X線診断および内視鏡的に，胃の悪性腫瘍とまぎらわしい所見を呈することが，Konjetzny（1928，1938）¹⁾，Schindler（1937）²⁾らにより指摘されて以来，この病変が注目されるようになり，その報告例も増加しつつある現実を踏まえ，この機会に自験例および他2施設からの提供例と既報告例を参考とし，文献的考察を加えて，この病変の内視鏡像の特徴について解析を試み，内視鏡診断の可能性と限界，殊に誤診されやすい悪性リンパ腫と早期胃癌を中心に，その鑑別の可能性を追求した．

　Three cases of benign lymphoma of the stomach were presented and the endoscopic findings were analyzed.

　All the cases were classified into “diffuse and flat form” of Nakamura. The gross features described diffuse redness, coarsely granular elevations, multiple erosions and ulcerations in a large Ⅱc like depression. These findings rise and fall frequently during the follow-up.

　For the differential diagnosis, the most important is a depressed type of early gastric carcinoma such as Ⅱc or Ⅱc+Ⅲ. The distinguishing features are convexed tips of disrupted folds at the margins of the depression and a marginal line not clearly demonstrated all the way through the margin in benign lymphoma. It seems easy to distinguish benign lymphoma from advanced malignant lymphoma with characteristic features, but difficult to distinguish from a superficially existing lymphoma.

　It has been said that “localized and hypertrophic form” of Nakamura not experienced by us, shows circumscribed and thickened mucosal folds characterized by a central ulceration. This type of lesion resembles a protruded type of early gastric carcinoma such as Ⅱa or Ⅱa+Ⅱc. A distinguishing feature from early gastric carcinoma is smoothly tapering elevation. It is almost impossible to differentiate this type of benign lymphoma from malignant lymphoma and some sorts of submucosal tumor.

　Endoscopic biopsy plays an important role in excluding the possibility of carcinoma and in a positive diagnosis of beiugn lymphoma when big specimens are obtained. However, a long-standing lesion with a probable diagnosis of benign lymphoma should be operated on regardless of endoscopic appearances, because malignant lymphoma can not be ruled out completely.