表層型胃悪性リンパ腫と慢性胃炎の内視鏡的鑑別診断

Differential Diagnosis Through Comparison of Endoscopic Findings Concerning Superficial Gastric Lymphoma and Chronic Gastritis

要旨　表層型胃悪性リンパ腫の内視鏡所見の特徴を慢性胃炎と対比して解説した．自験例23例中19例（83％）はlow-grade MALTリンパ腫またはその成分を含んでいた．深達度は19例（83％）がsm，H.pyloriは18例中15例（83％）が陽性であった．多発びらん型病変は，やや厚みのある粘膜混濁領域に多発性の小円形びらんを混在するもので，平坦びらん性胃炎，萎縮性胃炎と区別される．敷石粘膜型病変は“溝状びらんに囲まれた粗大顆粒像”を呈するが，同所見を呈する特異な慢性胃炎が存在する．限局性皺襞腫大型病変の表面には微細な凹凸や発赤びらんがみられ，皺襞腫大性胃炎と区別される．多発たこいぼ型病変とリンパ球性胃炎との鑑別は困難である．組織学的にMALTリンパ腫と異なる胃RLH症例が存在し，内視鏡的に潰瘍型悪性リンパ腫様であるが，抗潰瘍治療により平坦粘膜に治癒するという特徴がみられる．

　Endoscopic features of superficial gastric lymphomas are presented focusing on the differences from those of chronic gastritis. Superficial gastric lymphomas tended to be low-grade MALT lymphomas or to have low-grade component (83% : 19/23), to be limited to the submucosal layer (83% : 19/23), and to involve Helicobacter pylori infection (83% : 15/18) . According to endoscopic features, superficial gastric lymphomas were subdivided into six types. Except IIc-like type and submucosal tumor type, endoscopic findings of the remaining 4 types of lymphomas resemble those of chronic gastritis. Multiple-erosion type lymphomas give rise to small round erosions in the slightly thickened muddled mucosal area, and are different from flat erosive gastritis and atrophic gastritis. Cobblestone-mucosa type lymphomas give rise to coarse granules surrounded by ditch-like erosions. We found peculiar cases of chronic gastritis showing cobblestone mucosa indistinguishable from this type of lymphoma. Partial-fold-swelling type lymphomas give rise to fine reddish erosions with uneven surface found on partially-enlarged folds, and which are different from rugal hyperplastic gastritis. Varioliform type lymphoma resembles lymphocytic gastritis. Reactive lymphoid hyperplasia of the stomach, which has polyclonal immunoglobulin gene rearrangement and is histologically different from MALT lymphoma, shows ulcerative-lymphoma-like ulcer and on being cured by anti-ulcer therapy, it gives rise to flat mucosa.