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Non-Histaminergic Angioedema — SCE Dermatology MCQ

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HardInflammatory DermatosesNon-Histaminergic AngioedemaSCE Dermatology

A 50-year-old woman has recurrent episodes of angioedema WITHOUT urticaria. She does not respond to antihistamines. C4 is normal. C1 esterase inhibitor level and function are normal. What is the most likely diagnosis?

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Correct answer: B — Idiopathic non-histaminergic angioedema (recurrent angioedema unresponsive to antihistamines with normal complement — consider bradykinin-mediated mechanisms)

The best answer is “Idiopathic non-histaminergic angioedema (recurrent angioedema unresponsive to antihistamines with normal complement — consider bradykinin-mediated mechanisms)”. The diagnosis follows the defining morphology, distribution, histopathology and time course; management changes when red flags, scarring, systemic disease or malignancy risk are present. The alternatives “Hereditary C1-inhibitor-deficient angioedema, after clinicopathological correlation, after specialist assessment, when the full phenotype supports it”, “Acquired C1-inhibitor-deficient angioedema, after specialist assessment, when the full phenotype supports it, within an appropriate UK pathway”, “Histaminergic spontaneous angioedema, when the full phenotype supports it, within an appropriate UK pathway”, “Angiotensin-converting-enzyme-inhibitor angioedema, within an appropriate UK pathway, after clinicopathological correlation, after specialist assessment” are clinically adjacent possibilities, but they do not fit the defining morphology, distribution, histopathology, risk signal or management sequence in this stem.

Reference: British Association of Dermatologists clinical resources: https://www.bad.org.uk/