Type III hyperlipoproteinemia with xanthomas and multiple myeloma

There are several unusual features to this case. Planar xanthomas can be associated with myelomas, but usually in the setting of normal lipids. Type III hyperlipoproteinemias are not usually refractory to standard therapy and are only rarely associated with IgA myeloma. IgA antibodies complexed to the patient's VLDL caused gross impairment of VLDL metabolism. The patient's apolipoprotein E genotype (heterozygote E2/E3) is not typical for expression of the heritable type III phenotype (homozygote E2/E2). These features support a causal relationship between this patient's multiple myeloma and type III hyperlipoproteinemia rather than two independent, coexistent conditions.