A CURIOUS CASE OF ACQUIRED ANGIOEDEMA: DIAGNOSIS AND MANAGEMENT OF C1-INH-AAE WITHOUT AN UNDERLYING CONDITION

Abstract

<h3>Introduction</h3> Angioedema results from localized fluid extravasation into interstitial tissues mediated by mast cells, bradykinin, and other undescribed mechanisms. Recurrent bradykinin-mediated angioedema is most often hereditary, though can rarely be acquired due to autoantibody production. We present a case of acquired C1 esterase inhibitor deficiency (C1-INH-AAE) requiring tracheotomy, and review additional evaluation and maintenance therapy following diagnosis. <h3>Case Description</h3> An 80-year-old woman with multiple comorbidities was referred after two episodes of facial angioedema without clear triggers, including severe recurrence involving her oropharynx that required tracheotomy. Family history was negative, and both losartan and NSAIDs were previously discontinued. Initial evaluation following episode demonstrated indeterminate C1 inhibitor functional assay, low quantitative C1 inhibitor, and borderline C4 level; C1-INH-AAE was subsequently confirmed with C1 esterase autoantibody evaluation. She was prescribed icatibant rescue therapy and started on cetirizine and prednisone 5mg every other day without further recurrence of oropharyngeal symptoms. No evidence of underlying oncologic or rheumatologic process was found on extensive evaluation. During ongoing management over 5 years, tracheotomy was taken down, daily antihistamine was discontinued, and prednisone has been successfully titrated for symptoms associated with local tissue damage and iron deficiency anemia. <h3>Discussion</h3> C1-INH-AAE is a rare cause of recurrent angioedema which presents in older age and is often associated with underlying lymphoproliferative, malignant, or autoimmune disease. Our case reminds that acquired angioedema should be considered in older adults with negative family history, however had no evidence of commonly associated conditions on extensive evaluation. Her subsequent course also offers insight into management of triggers and maintenance therapy.