Primary B-cell gastric lymphomas of mucosa-associated lymphoid tissue. Histological and immunohistochemical study of ten cases on surgical specimens.

Ten cases of gastric mucosa-associated lymphoid-tissue B-cell lymphoma were studied on surgical specimens by histology and immunohistochemistry, with monoclonal and polyclonal antibodies for B- and T-cells. For the first time, percentage of centroblast-like cells was appreciated, using their LN1 positivity, by opposition to the negativity of centrocyte-like cells (LN2 immunoreactivity alone). Lymphomas were divided into four main groups: A) centrocyte-like cells; B) centrocyte-like cells and immunocytoma; C) centrocyte-like cells admixed to centroblast-like cells; and D) centrocyte-like cells, immunocytoma and at least 30% of centroblast-like cells. Group C was divided into 3 subgroups: C1 (rare centroblast-like cells); C2 (30-50% of centroblast-like cells); and C3 (predominant centroblast-like cells). Therefore low grade (A, B, C1) and high grade malignancy groups (C2, C3, D) were identified: this preliminary subdivision could be extended in larger series and applied to mucosa-associated lymphoid-tissue lymphoma from other sites. Furthermore, the possible prognostic significance of this subdivision could be evaluated by correlation with long term follow-up.