Effective Management of Type III Hereditary Angioedema with Lanadelumab: A Case Report

Introduction Hereditary angioedema is a rare disorder characterized by recurrent episodes of edema in the skin and mucous membranes caused by a quantitative or qualitative defect in the C1 inhibitor, with a consequent exaggerated production of bradykinin. This clinical case presents the evolution and treatment of a patient with type III hereditary angioedema, initially diagnosed as type II. Presentation of the Case A 70-year-old patient with a history of hypertension, type II diabetes mellitus, and depression. She presented her first episode of angioedema in 1994 followed by multiple hospitalizations for facial angioedema and respiratory distress. Laboratory studies in 2017 revealed a C4 level of 3 mg/dl, normal C1q, and decreased functional C1 inhibitor (25%), leading to the diagnosis of hereditary angioedema type II. During a critical episode in 2020, orotracheal intubation (IOT) was required; endovenous C1 inhibitor had no effect, so icatibant was administered showing a good response. Upon further monitoring, C1 inhibitor and C4 values normalized, changing the diagnosis to hereditary angioedema type III, which made obtaining medication even more difficult. The patient continued to experience increasingly frequent angioedema attacks, requiring a large number of icatibant syringes. As of March 2025, prophylactic treatment with lanadelumab was initiated, resulting in the absence of angioedema crises up to date. Discussion This case highlights the importance of an accurate diagnosis in hereditary angioedema disorders, as effective treatment depends on it. The transition from type II to type III diagnosis highlights the need for ongoing evaluation in acquired or genetic undiagnosed cases. The introduction of lanadelumab has proven to be an effective therapeutic option, significantly improving the quality of life of a patient with type III hereditary angioedema.