Splenic marginal zone lymphoma with or without plasmacytic differentiation

We report a series of 31 cases of splenic marginal zone lymphomas with an e nlarged spleen and a multimicronodular macroscopic pattern. Two groups, A a nd B, were distinguished based on the presence (A) or absence (B) of a lymp hoplasmacytic component with monoclonal immunoglobulin expression in the cy toplasm. There were no differences between the groups as far as age, sex, s pleen weight, and progression. The only difference was the presence in grou p A of a monoclonal serum component and autoimmune disorders, particularly autoimmune hemolytic anemia. In most cases in which a liver and/or bone mar row biopsy was performed, lymphomatous infiltration was detected. Seven cas es had a seric monoclonal IgM of 5 g/L or more and liver or bone marrow inf iltration, corresponding to the definition of Waldenstrom's macroglobulinem ia. Lymphoma cells had a monocytoid, centrocytoid and, in group A, lymphopl asmacytic morphology. The lymphomatous cells were positive for CD20, CD45 R A, and bcl-2. They expressed IgD in 9 cases, partially in 6, and were negat ive for IgD in 9 of the 24 cases studied. Progression seems to be slow, wit h a long survival. Three patients presented with transformation into a larg e B-cell lymphoma, which was responsible for death in two patients.