Photo Credit: SaevichMikalai

The following is a summary of “Angioedema due to acquired C1-inhibitor deficiency associated with monoclonal gammopathies of undetermined significance,” published in the September 2024 issue of Allergy & Immunology by Lahuna et al.  

Monoclonal gammopathies of undetermined significance (MGUS)-associated angioedema due to acquired C1-inhibitor (C1-INH) deficiency (AAE-C1-INH) has not been specifically described before.   

Researchers conducted a retrospective study to assess the clinical characteristics and treatment outcomes of patients with this condition. 

 They conducted a French national, 30-year, retrospective observational study of MGUS-associated acquired angioedema. The study included 41 patients and examined biological, clinical characteristics, and treatment outcomes. 

 The results showed that 41 patients with MGUS-associated AAE-C1-INH were included in the study, with 68% displaying anti-C1-INH antibodies. The monoclonal component was IgM in 24 patients, IgG in 11 patients, and IgA in 6 patients. The mean age at the first angioedema attack was 63 years (SD= 13), and the mean age at diagnosis was 66 years (SD = 11). Acute attack treatments benefited 88% of patients, while 77% received long-term prophylaxis, including danazol, tranexamic acid, or lanadelumab. The median follow-up was 7 years, during which 14 patients (33%) evolved into well-defined malignant hemopathies.  

Hematological treatment was administered to 50% of patients, including rituximab alone for patients with recurrent angioedema attacks and anti-C1-INH antibodies, or chemotherapy combinations for those who evolved into lymphoma (7 patients) or myeloma (3 patients). About 15 patients (35%) achieved clinical complete remission of angioedema at the last visit, with 60% of those having undetectable serum monoclonal immunoglobulins. 

 The study concluded that complete remission of AAE-C1-INH is closely linked to remission of the underlying hematological malignancy, as indicated by undetectable monoclonal immunoglobulins. 

Source: jaci-inpractice.org/article/S2213-2198(24)00942-5/fulltext