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.
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
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.
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.