早期胃形質細胞腫の1例

Early Gastric Plasmacytoma, Report of a Case

要旨　患者は44歳，男性．検診の胃内視鏡検査で病変を指摘され当科紹介となった．胃X線検査では前庭部前壁にバリウムをはじく領域が存在し，胃小区は粗な印象であった．胃内視鏡検査では前庭部前壁に黄白色調の顆粒状の領域があり，周囲粘膜よりわずかに隆起していた．生検からも胃形質細胞腫を疑い幽門側胃切除が施行された．組織学的に，粘膜固有層内にRussell体を有する形質細胞のびまん性増生が認められた．lymphoepithelial lesion(LEL)を示す部位はごく少数であった．免疫組織化学的にはκ鎖陽性であり，IgH遺伝子再構成の検討でもmonoclonalityがあると判断された．以上より，胃MALTリンパ腫を経ない純粋な胃形質細胞腫と診断した．

　A case of early gastric plasmacytoma without any features of gastric lymphoma of mucosa-associated lymphoid tissue (MALT) is reported. A 44-year-old male patient was introduced to our department and presented gastric disease on screening endoscopic examination. X-ray examination showed a blocked lesion that had an irregular area at the anterior wall of the antrum. Endoscopic examination showed a yellowish-white granular lesion that was slightly elevated. We diagnosed pure plasmacytoma from pathological examination of the biopsy specimen The patient received distal gastrectomy. Histologically, plasma cells with red crystalline inclusions were diffusely distended at the mucosae propria. There were only a few lymphoepithelial lesions. During immunohistochemical study, Immunoglobulinκlight-chain restriction was revealed by in situ hybridization. In addition, the monoclonality of IgH gene was verified by polymerase chain reaction. There was no feature of gastric lymphoma of MALT, so a definite pathologic diagnosis of gastric de novo plasmacytoma that was not differentiated from gastric lymphoma of MALT was made.