Multiple myeloma, cryoglobulinemia and xanthomatosis. Distinct clinical and biochemical syndromes in two patients.

Studies were carried out in two patients with multiple myeloma (immunoglobulin G, [IgG], K light chain), cryoglobulinemia and xanthomatosis with clinical features and lipid transport abnormalities which were quite different. One patient had nodular xanthomatosis and lipemia with delayed triglyceride and apolipoprotein removal. In vivo heparin resistance was present and heparin-paraprotein interaction was shown in vitro. The lipoprotein removal defect may have been due to impaired uptake of the "remnants" of glyceride-rich lipoproteins. Abnormalities were found both in primary platelet aggregation and in the platelet release reaction. The second patient had diffuse plane xanthomatosis with normal lipids. An orange cryoprecipitate contained IgG, beta- and prebeta lipoproteins, albumin, carotenoids and about half of the serumcholesterol. Triglyceride turnover was normal. These observations show that M-proteins may interfere with lipid transport by at least two mechanisms and illustrate the clinical diversity of xanthomatous myeloma.