Hereditary Angioedema, Drug Hypersensitivity Reactions

Thanks Ambika for presenting an excellent case! This is a case of a young person who initially presented with a dramatic episode of unilateral arm swelling after injuring a finger, with subsequent episodes of recurrent localized edema without pruritus throughout their body, including episodes of gut edema, found to have hereditary angioedema.

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Main points:

1) In approaching edema, important questions to ask include laterality, pain/ rash, albumin levels, exposures, atopy personal and family history. See this previous report for the differential of bilateral lower extremity edema.

2) C3 and C4 complement levels can be used in a workup of vasculitis to help distinguish pauci-immune vasculidities (they are normal).

3) Hereditary angioedema is an extremely rare diagnosis that presents as recurrent episodes of localized edema without pruritus with or without triggers.


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Drug Hypersensitivity Reactions

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We played a matching game today as a review of the types of drug hypersensitivity reactions. This is a nice way to approach drug reactions, especially to think through a type I vs type IV reaction.

Hereditary angioedema

Here is a great review article about hereditary angioedema. A pearl is patients may present with only recurrent episodes of abdominal pain with GI distress (n/v/d) secondary to gut edema. Many of these patients will have failed usual allergy treatments for recurrent attacks and mortality can be high if undiagnosed due to airway obstruction.