内視鏡像の急激な変化を来し，悪性リンパ腫との鑑別が困難であった胃RLHの1例

Reactive Lymphoreticular Hyperplasia Which Was Difficult to Distinguish from Malignant Lymphoma, Report of a Case

要旨　患者は54歳，男性．半年前の内視鏡検査で，胃体下部前壁に粘膜集中を伴う陥凹性病変が発見された．生検の結果，悪性所見は得られず潰瘍瘢痕と診断された．しかし，6か月後の内視鏡検査時には，病変は胃体下部前壁から大彎にわたり広範にみられ，病巣内には多数の潰瘍性病変と結節状隆起が混在していた．生検では悪性リンパ腫が疑われ，内視鏡像を考え合わせ，表層型悪性リンパ腫と診断され胃切除術が行われた．切除標本の肉眼所見では病巣部には多発性のびらんがみられたが，健常部との境界は不明瞭であった．病理組織学的には，粘膜下層を中心にリンパ球，プラズマ細胞など単核球の高度の集簇が認められた．免疫組織化学的には，増生するリンパ球はT-cellまたはB-ce11のどちらか一方のmonoclonalityはなく，腫瘍性増生とは断定できずRLHと診断された．本例は病変が急激に増大し臨床的には悪性リンパ腫と考えられた胃RLHの1例である．

　A 54-year-old male was admitted for further evaluation of a gastric lesion. The roentgenographic and endoscopic findings showed so-called cobblestone appearance at the anterior wall and greater curvature from the lower body to the angle with the macroscopic findings of malignant lymphoma, especially of the superficial spreading type. Operation was performed under the diagnosis of malignant lymphoma by routine examination of biopsy specimens and endoscopic findings. In the immunohistochemical study of the resected stomach, however, the infiltrated lymphocytes did no thave monoclonal B-cell or T-cell proliferation. This immunohistochemical study enabled us to make the final diagnosis of our case as reactive lymphoreticular hyperplasia. Therefore, immunohistochemical study was useful for the differential diagnosis of a gastric lymphoproliferative disease which was difficult to distinguish by routine examination of biopsy specimens.