Acquired C 1-inhibitor deficiency with angioedema due to pleomorphic immunocytoma in a patient with three malignant tumors: long-term follow-up data and presentation of an additional case

Abstract

Two cases of lymphoma-associated acquired C 1-inhibitor deficiency are described. In both patients, C 1-inhibitor deficiency and related symptoms preceded the diagnosis of the underlying neoplasm by several months. C 1-inhibitor deficiency was most likely due to consumption following immunocomplex formation. In both patients, a close relationship between low levels of C 1-inhibitor and tumor relapse was observed during follow-up. These findings indicate that measurement of C 1-inhibitor and complement factor C4 can be used as markers of disease activity in affected patients.

Lymphoma‐associated paraneoplastic angioedema with normal C1‐inhibitor activity: Does danazol work?

“…Decreased C1-INH activity leads to a decrease in serum levels of C4 and C2, the natural substrates of C1r and C1s. In acquired angioedema associated with lymphoproliferative disorders, the serum levels of C4 are therefore characteristically very low [3][4][5][6][7]12]. Our patient had persistently normal C1-INH and C4 levels during his episodes of angioedema.…”

“…Hereditary angioedema usually results from an inherited quantitative (type I) or qualitative (type II) deficiency of C1 inhibitor (C1-INH), the only intrinsic inhibitor of the first component of complement [1][2][3]. A syndrome of acquired C1-INH deficiency resulting in symptomatic angioedema is well recognized in association with B-cell lymphoproliferative disorders [3][4][5][6][7] with a prevalence of approximately 0.5% [3]. Unlike the hereditary syndrome, the acquired, angioedema syndrome typically presents with markedly decreased levels of C1, C4, and C1-INH [4] and appears to result from increased activation and consumption of both complement and its inhibitors [3,4,8,9].…”