16th February 2024

A 45-year-old male presents to the emergency department with facial swelling and stridor, requiring intubation

A 45-year-old male presents to the emergency department with facial swelling and stridor, requiring intubation. Trials of IM adrenaline and steroids were ineffective. After extubation, he recalled several wheals on his arms and legs that spontaneously resolved. He also experienced previous episodes of mild facial swelling that resolved.

He denies any prior exposure to any new substances or environments. He was not exercising at the time of the incident. His mother and grandfather had similar issues with facial swelling and rashes without any clear allergic cause. Serum tryptase levels during the episode were normal. C3 levels were normal, but C4 levels were low.

What is the likely underlying diagnosis?

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