Hereditary Angioedema with Normal C1 Esterase Inhibitor Refractory to Long-Term Prophylaxis: A Case Report

Hereditary angioedema (HAE) was classically thought to be related to a deficiency in the C1 esterase inhibitor (C1-INH). However, HAE with a normal C1 esterase inhibitor (HAE nC1-INH) is a rare disease that has been recently characterized. In this case, we describe a woman with a 21-year history of angioedema who, in the last two years, has experienced severe exacerbations that led to the formal diagnosis of HAE nC1-INH. The patient has been treated with current HAE long-term prophylaxis (LTP) and on-demand therapies but is still experiencing severe, frequent attacks. Our case describes the timeline of this patient’s presentation and provides valuable insight into the presentation and management of HAE nC1-INH.