臨床経過からみた胃MALTリンパ腫の評価―遺伝子診断を含めて

Clinicopathological Changes of Gastric MALT Lymphomas with or without Eradication of Helicobacter pylori

要旨　IsaacsonらがMALTリンパ腫の概念を提唱して以来，胃のリンパ増殖性疾患の診断は大きく変わりつつあるが，その確定診断は定義の明確さに比べて容易ではない．今回，RLHと診断された24例を彼らの基準に準じて見直し診断し，low-grade MALTリンパ腫，AL（atypical lymphoid cell proliferation）とされた12例の自然経過を検討した結果，low-grade MALTリンパ腫8例中4例，AL 4例中全例が生検上，慢性胃炎の像を呈するようになった．更にMALTリンパ腫およびALと診断された10例に対してH. pylori除菌を施行し，6例が生検上，慢性胃炎の像を呈した．また，遺伝子診断の可能性をIgHおよびbcl 2-JH再構成，p53，APC，DCCのLOHについて検討した結果，IgH再構成が補助診断に有用であることが示唆された．以上の結果を踏まえ，現時点でのリンパ増殖性疾患の臨床的取り扱いについても言及した．

　We followed natural couses of eight cases of low-grade MALT lymphomas and four of atypical lymphoid cell proliferation (AL). The mean observation period was three years, raising from two months to 7.5 years. Although four cases of low-grade MALT lymphomas had no ovbious histological changes in biopsy specimens, remained four cases and all of AL cases changed to chronic gastritis histologically.

　Then, nine cases of low-grade MALT lymphomas and one case of AL underwent eradication of Helicobacter pylori (H. pylori). Histological findings changed to chronic gastritis in five cases with MALT lymphoma and one case with AL, four of which accompanied with improved endoscopic findings. In only one patient with MALT lymphoma endoscopic findings became worse. Two cases which showed monoclonal pattern of IgH rearrangement by PCR changed to polyclonal pattern after eradication of H. pylori. No LOH of APC, DCC, p53 genes and no bcl-2 rearrangement were detected in all cases before and after eradication.

　We concluded that pathological and endoscopic findings of MALT lymphomas were changeable during a long observation period. Furthermore, eradication of H. pylori would be valuable approach for precise diagnosis of lymphoproliferative disorders of the stomach. Gene analysis of IgH might be useful for differential diagnosis from MALT lymphoma and borderline lesion.