1st July 2023

Angioedema

Background

Angioedema is characterised by a sudden, localised, deep swelling of the subcutaneous tissue of the skin and mucous membranes, caused by increased endothelial permeability and plasma extravasation in the dermis and submucosa. It varies in severity and can be life threatening.

Classification and Pathophysiology

• Histaminergic – histamine and other vasoactive molecules are released. This type of angioedema can present with associated urticaria, anaphylaxis and bronchospasm.
• Non-histaminergic – bradykinin and complement derived mediators are released.

Aetiology

• Acute allergic
• Hereditary – C1 inhibitor deficiency (type I) or low activity (type II) causes an increase in bradykinin levels
• Acquired C1 inhibitor deficiency– secondary to autoimmune disease, malignancy or infection
• Iatrogenic – NSAIDs, ACE inhibitors (non-allergic)

Clinical Features

• Skin coloured or pale red swellings of the skin or submucosal tissue
• Lesions vary in size and are asymmetrical
• Generally affects the face or genital skin, however limbs, airways and abdomen can also be affected
• Associated urticaria in 1/3 of cases

Angioedema causing periorbital swelling. 

Image Source: Wikimedia Commons (2008). Angioedema2010, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Angioedema2010.JPG (Accessed on: 1 February 2022).

Investigations

• Routine blood tests: full blood count, liver function tests, renal function, c-reactive protein
• Other blood tests: thyroid stimulating hormone, tryptase, IgE, thyroid antibodies, C1 inhibitor concentration and function, complement, ANA, ANCA
• Skin biopsy

Treatment

• Stop triggering factor
• Keep the airways patent
• Treat any underlying infection
• Antihistamines
• Corticosteroids
• C1INH concentrate (for non-histaminergic angioedema)
• Prophylaxis: Danazol

Prognosis

Self-limiting after a few hours or days.