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Hereditary angioedema — ABIM Board MCQ

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HardRheumatology/Allergy/ImmunologyHereditary angioedemaABIM Board

A 22-year-old has recurrent nonpruritic lip and hand swelling with severe episodic abdominal pain. There is no urticaria, antihistamines do not help, her father had similar attacks and C4 is low. Which abnormality is most likely?

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Correct answer: D — Deficient or dysfunctional C1 esterase inhibitor causing bradykinin-mediated angioedema

The best answer is “Deficient or dysfunctional C1 esterase inhibitor causing bradykinin-mediated angioedema”. Hereditary angioedema usually results from deficient or dysfunctional C1 inhibitor, causing uncontrolled kallikrein-bradykinin activity. It produces nonurticarial swelling and abdominal attacks and does not respond to antihistamines. Low C4 supports the diagnosis, whereas IgE and urticaria are histamine-mediated.

Reference: 2021 WAO/EAACI Guideline for Hereditary Angioedema: https://pmc.ncbi.nlm.nih.gov/articles/PMC9023902/