An unusual case of acquired angioedema associated with monoclonal gammopathies of uncertain significance.

Acquired angioedema (AAE) is a rare disease due to the C1 esterase inhibitor (C1-INH) deficiency. Clinically, its symptoms are similar to hereditary angioedema (HAE) with hereditary C1-INH deficiency. Both conditions have the potential to cause upper airway obstruction, which can be fatal in clinical practice and thus require intense attention. Here, we'd like to discuss the clinical presentation, diagnosis and follow up of a special case of AAE associated with monoclonal gammopathies of unknown significance (MGUS) with recurrent upper airway obstruction. The patient was regularly followed up after being discharged from our ward. Measurements of C3-C4 levels were carried out by a hematological test. Due to the rarity of such a disease, especially in Chinese people, relevant diagnosis methods are missing in this patient, so the patient was only diagnosed with AAE-C1-INH associated with MGUS clinically. The latest follow up showed that he still underwent recurrent upper airway obstruction; thus, he remained in a tracheostomy state due to a lack of proper medication prophylaxis and died eventually. This unusual case reminds emergency physicians to pay attention to such disease during clinical practice, and relevant diagnosis method should be improved.