Xanthomas are a common manifestation of
lipid metabolism disorders. They include hyperlipemic
xanthoma, normolipemic
xanthoma, and a related condition,
necrobiotic xanthogranuloma (NXG). All 3 forms can be associated with monoclonal
immunoglobulin (MIg). In an attempt to improve diagnosis, understanding, and treatment of this association, we retrospectively analyzed a personal series of 24 patients (2 hyperlipemic
xanthoma, 11 normolipemic
xanthoma, and 11 NXG) and 230 well-documented reports from the literature. With the exception of the nodules and plaques featured in NXG, the clinical presentation of xanthomatous lesions usually resembled that seen in common hyperlipidemic forms and could not be used to suspect MIg-associated
xanthomas. Extracutaneous sites were not rare. The MIg was an
IgG in 80% of cases. Myeloma was diagnosed in 35%. Hypocomplementemia with low C4 fraction was present in 80% of studied patients. Low C1 inhibitor serum levels were found in 53%.
Cryoglobulinemia was detected in 27%. These abnormalities suggest
immune complex formation because of interactions between the MIg and
lipoproteins and argue in favor of a causal link between MIg and
xanthomas.
Monoclonal gammopathy therapy could thus be an option. Indeed, among the patients who received
chemotherapy, hematologic remission was accompanied by improvement in
xanthoma lesions in several cases.