CD40LG and monoclonal gammopathy: WM belongs to the spectrum of IgM gammopathies, encompassing a wide and heterogeneous group of hematological conditions, ranging from asymptomatic IgM monoclonal gammopathies of undetermined significance (IgM-MGUS), through symptomatic IgM related disorders (such as IgM gammopathies of renal or neurological significance), to asymptomatic WM (aWM), and ultimately to symptomatic WM [7,8,9,10,11,12].