Helicobacter Pylori感染の病理―リンパ腫との関係

Pathology of Helicobacter pylori Infection: Its Relation to Primary Gastric Lymphoma

要旨　粘膜関連リンパ組織（mucosa-associated lymphoid tissue; MALT）型と解釈される原発性胃リンパ腫症例は多い．その組織学的特徴は，小型ないし中型異型リンパ球（centrocyte-like cell）のびまん性単調な浸潤，反応性リンパ濾胞の混在，顕著なリンパ上皮性病変などである．種々の程度に大型異型リンパ球が混在し，低悪性度リンパ腫から高悪性度への変異が生じうることを示唆する．WotherspoonらがMALT型胃リンパ腫とHelicobacter pylori胃炎との密接な関係を示して以来，Helicobacter Pylori除菌が治療として有効であることが報告されている．個々の症例につき最適な治療を選択するため，悪性度の判定基準を明らかにする必要があろう．

　Many cases of primary gastric lymphoma are now morphologically interpreted as mucosa-associated lymphoid tissue (MALT) type. Histological features of this type include : diffuse and monotonous infiltration of small to medium-sized atypical lymphocytes (centrocytelike cells), presence of lymph follicles with reactive germinal centers, prominent lymphoepithelial lesions. Occasionally. among the centrocyte-like cells, there are more or less large atypical lymphoid cells, suggesting a transformation of low grade lymphoma cells to high grade. From the reports in the literature, it is reasonable to estimate that approximately one-third to a half of high grade B-cell lymphoma cases occured through transformation of an antecedent low grade MALT type lymphoma. After Wotherspoon et al. demonstrated a close association of MALT type gastric lymphoma with Helicobacter pylori (HP) gastritis, a number of reports followed their observation by showing that eradication of HP is effective as a treatment of gastric lymphomas of this type. Concerning the opimal therapy, it would be important to clarify the pathologic criteria to determine the grade of malignancy in each case of primary gastric lymphoma.