A CASE OF HEREDITARY ANGIOEDEMA SUBTYPE SWITCH

Abstract

<h3>Introduction</h3> Hereditary angioedema (HAE) is a condition that is described by recurrent episodes of edema without pruritis that can involve multiple different organ systems including skin, gastroenterological tract, and upper respiratory tract. HAE arises from deficiency or abnormality of C1 inhibitor (C1-INH). HAE can be classified into two different classes. HAE-type I is a deficiency in C1-INH resulting in low plasma protein and abnormal functional C1 esterase level. HAE-type II is a dysfunctional C1-INH resulting in low plasma protein but normal functional C1 esterase. <h3>Case Description</h3> A 54-year-old man presents to his primary care doctor's office with a longstanding history of intermittent abdominal pain and and facial swelling lasting 12-24 hours. He has been evaluated by multiple other specialists including Gastroenterologists without an official diagnosis. He was seen by an Allergist and was diagnosed with HAE- type II after his functional C1 esterase inhibitor was normal, C3 complement was low range, and C4 complement was low. He was diagnosed with lymphoma around the same time of his HAE-type II. He was treated with Danazol and his symptoms resolved. Shortly after, the repeat functional C1 esterase was much lower, C3 and C4 complement was still low. It had appeared that he was now consistent with HAE-type I. <h3>Discussion</h3> This HAE subtype switch has not yet been described in the medical community. HAE is condition that is still misdiagnosed amongst medical specialities given the lack of understanding despite it being commonly reported condition as it may mimic other IgE mediated reactions.