Various clinical syndromes that associate paraproteinemia and complement depletion have been described in the last three decades. Among these, cryoglobulinemias, acquired Clq deficiency, and acquired deficiencies of the classical pathway of complement can be associated with B-cell lymphoproliferative disorders. Some specific symptoms should alert the clinician to suspect an underlying malignancy. In this report, we review the pathogenesis, symptomatology and therapeutic options of these clinical conditions.