Reactive plasmacytoma of the stomachの症例と発生機序

A Case of Reactive Plasmacytoma of the Stomach with Reference to its Mechanism of Evolution

　形質細胞腫は，①多発骨髄腫，②単発性骨髄腫，③形質細胞性白血病，④髄外性形質細胞腫の4型が分けられる．そのうち，①，②，③は悪性だが，④には良性，悪性，およびその中間型（移行型）がある．髄外性形質細胞腫は現在までに約250例の報告がある．その発生部位は上気道，口腔が圧倒的に多く，髄外性骨髄腫の約80％を占める．その他には，消化管，肺，リンパ節，顎下部，甲状腺，眼瞼結膜，皮膚，腟，乳腺，腎，睾丸等に発生する．消化管における発生頻度は，小腸，胃，大腸の順である．胃の髄外性形質細胞腫は，Vasiliu（1939）が第1例目を報告して以来，約33例が報告された．本邦における報告は1例にすぎず，しかもそれは一部細網肉腫の性格を有する悪性型であった．筆者らは今回本邦第2例目の胃の髄外性形質細胞腫を経験したが，それは良性型であって，reactive lymphoreticular hyperplasia（R. L. H.）と近似関係にあると思われる興味ある症例であった．このような良性型は本邦最初の症例であるので報告し，その発生機序と周囲病変との関係について述べる．

　Case: 33-year-old male. He was examied by x-ray and endoscopy because of pain in the upper abdomen, and was suspected to harbor reactive lymphoreticular hyperplasia of the stomach. The resected stomach also revealed not only mutiple ulcers but also depressions scattered around them. The lesion as a whole colsely resembled RLH (reactive lymphoreticular hyperplasia). Histologically, the majority of the pyloric part, especially the lamina propria and submucosa beneath the small protrusions around the ulcer, showed infiltrative hyperplasia of juvenile plasma cells. A part of them were immature and hard todiscriminate from cells of reticuloendothelial origin. Unna Pappenheim stain revealed that not only juvenile plasmocytes were strongly pyroninophilic, but also cells of the reticulo-endo-endothelial system showing gradual transition to plasma cells were also pyronincphilic in varying degree. These plasma cells are thought to arise out of reticuloendothelial system in the lamina propria. The lesion in the present case is regarded as a pathological entity simulating RLH, and we have proposed todesignate it as reactive plascytoma of the stomach. Its mechanism of evolution has also been discussed in this paper with reference to its involvement with other allied diseases.

　Although this is the second report of primary plascytoma of the stomach in Japan (the first was made by Genda), the one by Genda was of malignant nature, so that this is the initial report of benign plascytoma. Benign plascytoma so far reported from abroad do not tell us whether it is closely related with RLH. On that account, our case is the first accurate report of benign plascytoma closely resembling RLH. Careful observation would surely reveal increasing numbers of reactive plasmacytoma of the stomach. Much depends on the efforts of investigators in this country.