Abstract

Acquired angioedema (AAE) is a very rare condition caused by an acquired deficiency in C1 esterase inhibitor (C1 INH). Pathogenesis of AAE can entail abnormal B cell lymphoproliferation ranging from benign monoclonal gammopathy of undetermined significance (MGUS) to malignant forms of lymphoma. Symptoms related to MGUS or malignancy are often salient and age is often used as a diagnostic tool in considering in making this diagnosis. These bradykinin-mediated angioedema episodes commonly involve face, gastrointestinal system, and pharynx with associated potential for fatality and lack associated urticaria. Hence early diagnosis is vital. This case is unique, in that it describes a very early age of presentation of AAE related to MGUS. Given young age and lack of symptoms associated with MGUS, diagnosis was delayed and significant patient morbidity and healthcare expenses occurred which could have been avoided. A 41 year-old male presented to the allergy/immunology clinic with facial, lip, and tongue swelling following tooth extraction. His history began 5 years prior, after suffering complications from a motor vehicle accident including anterograde amnesia, multiple broken ribs, and a splenic hemorrhage requiring splenectomy. Six months after the accident he developed acute onset bilateral facial swelling, lip swelling, and difficulty breathing. He had no family history of angioedema, was not taking any medications, and his serum tryptase level checked during the episode was normal. He was diagnosed with presumed food-induced allergic angioedema. The patient suffered four additional episodes of varying degree over the next five years and developed clinical depression. Immunological evaluation showed low C1-INH, low C1-INH functional percentage, C4, C2, and C1q, consistent with AAE. Further workup to determine the etiology of AAE included serum protein electrophoresis demonstrating an M-spike in the gamma region with immunofixation showing a monoclonal protein band and a serum IgM level of 1.3 g/dl. The patient was diagnosed with AAE related to MGUS.

Keywords: Acquired angioedema, monoclonal gammopathy of undetermined significance, C1 esterase inhibitor