[Usefulness of the immunologic phenotype in the diagnosis of chronic lymphoproliferative syndromes with splenomegaly as the dominant clinical manifestation].

From a total number of 221 patients with leukaemic lymphoproliferative syndromes studied at the Hospital dos Capuchos, in Lisbon, seven patients whose cell morphology differed from that of "classical" lymphoproliferative syndromes were separated; marked splenomegaly without lymph node enlargement was present in all of them. Immunophenotypic studies confirmed B-cell origin of the lymphoproliferation in the seven patients. Small lymphocytes with mature appearance predominated in three of these cases, presenting as: a) the only cell population (with immunophenotype RR+, FMC7-, CD5+), b) along with a significant amount of prolymphocytes (RR+, CD5+, FMC7+), c) accompanying a population of cells with lymphoplasmacytoid differentiation (RR-, CD5-, CD38+, associated to serum monoclonal IgM). Those data strongly suggested that these three lymphoproliferative syndromes corresponded, respectively, to a classic B-cell chronic lymphocytic leukaemia, a chronic lymphocytic leukaemia with prolymphocytes, and an immunocytoma. In three other cases the morphology of the proliferating cells was intermediate between prolymphocytes and hairy cells (i.e., variant hairy cells) and they strongly reacted with monoclonal antibodies FMC7 and LeuM5 (CD11c), showing low positivity with antigens CD5 and CD25, in the absence of receptors for mouse red blood cells. The remaining B-cell lymphoproliferative syndrome studied had small centrocytes in peripheral blood, their phenotype being RR-, CD5+, FMC7+/-, CD10+ and CD38+, which suggested a centrofollicular lymphoma with leukaemic expression. In summary, the present study seems to confirm the heterogeneity of the chronic lymphoproliferative syndromes showing splenomegaly as an outstanding clinical feature. Immunophenotype along with cell morphology are important in the differential diagnosis, especially whenever splenectomy cannot be carried out, in order to choose the appropriate therapy.