MARGINAL ZONE B-CELL LYMPHOMAS - AN APPRAISAL

Although the Revised European-American Lymphoma Classification does no t utilize the term monocytoid B-cell Lymphoma, there are numerous reas ons to support its use in classifying lymphomas of so-called marginal zone B-cell type that contain a distinct population of malignant monoc ytoid B-cells. In addition, there are other B-cell lymphomas which hav e very distinctive morphological features, because they show multiple and very well demarcated histologies characterized by presence of cell s that appear to be (1) malignant monocytoid B-cells and malignant fol licular center cells, or (2) malignant monocytoid B-cells, malignant f ollicular center cells and malignant plasma cells, or (3) malignant mo nocytoid B-cells and malignant mantle cells. The neoplastic cells in e ach of the above three examples show identical light chain restriction and thus they are part of the same neoplastic clone. We believe that there are different types of precursor B-cells (memory or otherwise) f or the above cells, and an arrest in differentiation of these precurso r B-cells may readily explain the presence of these different morpholo gical combinations. Recognition of these morphological types may lead to further awareness of the possibilities of the existence of multiple , linked pathways of differentiation for lymphoid cells including the possibility of different types of precursor B-fells. Furthermore, an u nderstanding of the uniqueness of monocytoid B-cells would allow patho logists to use terminology that is less redundant and more precise. Co pyright (C) 1997 by W.B. Saunders Company.