[Life threatening angioedema caused by acquired C1 inhibitor deficiency associated with paraproteinemia and livedo racemosa].

A 61-year-old patient with life-threatening angioneurotic oedema was found to have an acquired C1-inhibitor (C1-INH) deficiency. In addition to lowered serum levels of C1-INH (both protein concentration and enzymatic activity), C2, C4 and CH50, which are characteristic for the hereditary form of angioneurotic oedema, markedly lowered C1q was found, which is typical for the acquired form. There were no antibodies against C1-INH. Repeated thorough examination disclosed no neoplasm, though the presence of neoplasm has often been reported to be associated with the acquired C1-INH deficiency. However, the patient showed persistent paraproteinaemia and paraproteinuria and developed livedo reticularis. Treatment with danazol resulted in a rise of the complement fraction levels and cessation of angioneurotic oedema. Paraproteinaemia and livedo reticularis persisted unchanged.