THE OCCURRENCE OF MONOCYTOID B-LYMPHOCYTES IN THE SPLEEN IN GASTRIC-CANCER

Occurrence of monocytoid B-lymphocytes (MBL) in spleens of 34 patients with gastric cancer was examined. Histologic findings of gastric canc er including classification, depth of invasion, and stage of disease w ere defined based on the General Rules for the Gastric Cancer Study (J apan). MBL were defined morphologically as having abundant pale cytopl asm with distinct cell borders and small nucleus often with reniform s hape. Immunohistochemically, these cells were B-cell in nature, i.e., CD15(-), CD43(-), CD45RA(+), CD45Ro(-), CD68(-), CD74(+), GDw75(+), Mx -PanB(L26)(+), MBI(+), EMA(-), PG-MI(-). Clusters of MBL were found in 14 of 34 (41%) patients: they were found to be directly adjoining to the periarterial sheath or apart from the white pulp. In the cases wit hout MBL, zonation of mantle zone and marginal zone was apparent with distinct secondary follicles in 72% of cases. Meanwhile, in spleens wi th MBL, the mantle zone showed atrophy in a half of cases, resulting i n indistinct zonation of the mantle zone and marginal zone. Secondary follicles were distinct in less than 30% of cases. Correlation of the occurrence of MBL, evaluated by Spearman's correlation coefficient, re vealed that the age was the most important factor (R = -0.4852, P = 0. 00364): the median age of patients with and without MBL was 75.7 and 6 1.7 yr, respectively. The MBL were increased in gastric cancer as comp ared with other cancers (P < 0.03) and with noncancer spleens (P < 0.1 ). The age of gastric cancer patients with MBL was older than those in other cancers and noncancer patients. Therefore occurrence of MBL in spleen might be a function of aging.