Primary gastric non-Hodgkin's lymphomas in Japan.

A pathological study was carried out on 124 cases of primary gastric non-Hodgkin's lymphoma (NHL) in Japan. Macroscopically the cases were divided into three groups; flat, polypoid, and ulcerative types. Early lymphomas were distinguished from advanced by the depth of infiltration. Histologically the commonest type was ML, immunoblastic (ML, ibl.). Most were high grade malignancy, in terms of morphology. Lymph node involvement was found in 44 cases. Correlation between macroscopical appearance, histological diagnosis, stage and accompanying reactive lymphoid hyperplasia (RLH) was studied. Three main prototypes of gastric NHL were noted: The first was macroscopically ulcerative type, histologically high grade malignancy and lacked RLH; the second was mostly flat, ML, lymphoplasmacytic/lymphoplasmacytoid (ML, l-p.) or ML, ibl., associated with RLH, and arose from neoplastic proliferation of the interfollicular lymphoid cell in RLH (termed gastric NHL of interfollicular type); the third was mostly flat, ML, centroblastic (ML, cbl.) or lymphoblastic (ML, lbl.), associated with RLH, and originated from neoplastic proliferation of the follicular center cell in RLH (gastric NHL of follicular type).