Lymphoplasmacytic lymphoma is a small B-cell lymphoma defined by the WHO as being characterised by clonal B-cells with plasmacytoid differentiation and secretion of a monoclonal paraprotein, popularly referred to as Waldenstrom's macroglobulinaemia when the paraprotein is of the IgM class [1, 2]. The gene discussed is CD40LG; the disease is lymphoplasmacytic lymphoma.