悪性リンパ腫─胃リンパ腫の分類：臨床の立場から

Clinical Classifications for Diagnosis and Treatment for Gastric Lymphomas

要旨●胃悪性リンパ腫の診療に必要な分類について概説した．組織分類はWHO分類に従う．胃ではMALT（mucosa-associated lymphoid tissue）リンパ腫とDLBCL（diffuse large B-cell lymphoma）の頻度が高い．肉眼/内視鏡分類は佐野分類と八尾分類が汎用され，MALTリンパ腫では表層型，DLBCLでは潰瘍型や隆起型が多い．MALTリンパ腫の生検組織診断にはWotherspoonらの組織スコア，治療後評価にはGELA（Groupe d'Etude des Lymphomes de l'Adulte）Gradeシステムに従うよう推奨される．病期分類にはLugano国際会議分類が用いられる．胃MALTリンパ腫の第一選択治療法はH. pylori除菌であるが，I/II₁期の胃DLBCLも約50％の症例で除菌治療が奏効する．各症例の形態学的特徴を理解し，治療前に適切な検査を行い，正確な組織および病期診断を行うことが重要である．

　Here, the classifications for the clinical diagnosis and treatment of patients with gastric lymphoma are reviewed. Histopathological diagnosis should be based on the criteria set by the World Health Organization classification. Among various gastric lymphomas, the most frequent histological type is MALT（mucosa-associated lymphoid tissue）lymphoma, followed by DLBCL（diffuse large B-cell lymphoma）. Although standard macroscopic or endoscopic classifications are yet to be established, either Sano classification or Yao classification are widely used in Japan. The most frequent endoscopic type in MALT lymphomas is the superficial type, whereas that in DLBCLs is the ulcerative and/or polypoid type. Wotherspoon score is recommended for confirming the histological diagnosis of MALT lymphoma, while evaluation of the post-treatment biopsy samples should be based on the Groupe d'Etude des Lymphomes de l'Adulte grading system. Clinical staging should be determined according to the Lugano International Conference classification. While the first-line treatment for gastric MALT lymphoma is Helicobacter pylori eradication, approximately 50% of gastric DLBCLs also respond to H. pylori eradication. Therapeutic strategy should be determined on the basis of histological type and clinical stage of the disease in each patient.