Dysbetalipoproteinemia and monoclonal gammopathy: A case report

Type III hyperlipidemia is a rare metabolic disorder characterized by elevated plasma concentrations of cholesterol and triglycerides. In subjects homozygous for the isoform E2 of apoprotein E, the disease becomes manifest when other factors that interfere with normal lipoprotein metabolism are present. Multiple myeloma has also been found to be associated with type III hyperlipidemia. We report a case with the typical manifestations of the disease (hyperlipidemia and palmar xanthoma) in whom the family history and blood analyses excluded pathologies potentially interfering with lipid metabolism. On electrophoresis of serum proteins, a monoclonal peak was detected. The patient was homozygous for the isoform E2 of the apoprotein E. Further blood analyses, bone marrow and roentgen examinations enabled the diagnosis of monoclonal gammopathy of undetermined origin. The association of type III hyperlipidemia with monoclonal gammopathy might be casual, although only the characterization of the antigenic determinants toward which the monoclonal antibodies are directed could be conclusive. The presence of several family members homozygous for the isoform E2, but without the clinical and biochemical characteristics of type III hyperlipidemia, and the poor response to diet and drug therapy suggest that gammopathy may play a role in determining hyperlipidemia.