[Hypocomplementemia of the first fractions of the classic pathway in normolipemic xanthoma planum with IgG1 monoclonal immunoglobulins (6 cases)]

Pathogenesis and treatment of xanthomatosis associated with monoclonal gammopathy

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.

Recurrent febrile panniculitis and hepatitis in two patients with acquired complement deficiency and paraproteinemia

Repeated episodes of febrile panniculitis and hepatitis were the main clinical features in two patients with an IgG1 kappa paraproteinemia and severe depletion of the early components of the classical pathway of complement (acquired C1 inhibitor deficiency). They did not have episodes of cutaneous angioedema or evidence of immune complex disease. In the more severely affected patient, the episodes responded to steroids. These features have not been described with acquired C1 inhibitor deficiency and may be related to complement activation.