[Necrobiotic xanthogranuloma in IgG kappa plasmacytoma and Quincke edema].

Necrobiotic xanthogranuloma is a non-X histiocytosis with unknown pathogenesis. It is associated with paraproteinaemia, and in rare cases with multiple myeloma. A decreased level of C1 inhibitor has been found in several cases without clinical manifestations of Quincke oedema. We report on a patient with necrobiotic xanthogranuloma and myeloma, in whom we found a decreased level of C1 inhibitor and recurrent episodes of manifest Quincke oedema. The indirect detection of auto-antibodies against the paraprotein with development of immune complexes is regarded as an explanation for the consumption of the C1 inactivator and the manifestation of Quincke oedema. The possibility of a causal relationship between paraproteinaemia and necrotic xanthogranuloma is discussed.