Extremely Late Diagnosis of Hereditary Angioedema Type I in an Elderly Female

This case presents an instance of an extremely delayed diagnosis of hereditary angioedema (HAE) type I in an elderly female with no significant past medical history. The patient had a prolonged history of recurrent lip swelling and itchiness dating back to her teenage years, leading to multiple visits to the emergency room (ER). These recurrent episodes were characterized by random onset and accompanied by generalized pruritus and urticaria. During these ER visits, the patient would be inappropriately treated for presumed hypersensitivity reaction due to her confounding environmental allergies presenting with urticaria, complicating and significantly delaying her diagnosis. The patient was adopted, and the family history was unknown. There was no history of medication use suggestive of acquired angioedema. At the time of the visit, she had signs of chronic lip changes and atopy. After an extensive workup, it showed severely low levels of C1 esterase inhibitor and borderline low to normal C4 and C1q, consistent with the diagnosis of HAE type I. Initial treatment with an on-demand C1 esterase inhibitor reduced the recurrence of lip swelling and transitioned to long-term prophylaxis use. Overall, the treatment outcome was generally successful, with less recurrence of lip swelling and ER visits.