Angioedema

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Angioedema (BE: angiooedema), also known by its eponym Quincke’s edema, is the rapid swelling (edema) of the dermis, subcutaneous tissue,[1] mucosa and submucosal tissues. It is very similar to urticaria, but urticaria occurs in the upper dermis.[1]

In the past, angioedema was referred to by the term angioneurotic edema, which wrongly implied that the phenomenon was due to neurosis.

Cases where angioedema progresses rapidly should be treated as a medical emergency as airway obstruction and suffocation can occur. Epinephrine may be lifesaving when the cause of angioedema is allergic. In the case of hereditary angioedema, treatment with epinephrine has not been shown to be helpful.

Apart from the common form, mediated by allergy, it has been reported as a side effect of some medications, in particular ACE inhibitors. Additionally, there are three autosomal dominant inherited forms known, due to mutations in the genes that control the clotting cascade, including the SERPING1 gene, which results in deficiency of the blood protein C1-inhibitor (type I HAE) and the F12 gene, which controls Factor XII (type III HAE). There is an additional type in which C1 levels are normal but C1 function is decreased (type II HAE). All three forms are called hereditary angioedema (HAE) or occasionally by the outdated term “hereditary angioneurotic edema” (HANE). In all forms of HAE, swelling may also occur in the digestive tract and other organs. It is life-threatening when it involves the larynx due to the potential for asphyxiation.

The skin of the face, normally around the mouth, and the mucosa of the mouth and/or throat, as well as the tongue, swell up over the period of minutes to several hours. The swelling can also occur elsewhere, typically in the hands. The swelling can be itchy. There may also be slightly decreased sensation in the affected areas due to compression of the nerves. Urticaria (hives) may develop simultaneously.

In severe cases, stridor of the airway occurs, with gasping or wheezy inspiratory breath sounds and decreasing oxygen levels. Intubation is required in these situations to prevent respiratory arrest and risk of death.

Sometimes, there has been recent exposure to an allergen (e.g. peanuts), but more often the cause is either idiopathic (unknown) or only weakly correlated to allergen exposure.

In hereditary angioedema, there is often no direct identifiable cause, although mild trauma, including dental work and other stimuli, can cause attacks. There is usually no associated itch or urticaria, as it is not an allergic response. Patients with HAE can also have recurrent episodes (often called “attacks”) of abdominal pain, usually accompanied by intense vomiting, weakness, and in some cases, watery diarrhea, and an unraised, non-itchy splotchy/swirly rash. These stomach attacks can last anywhere from 1–5 days on average, and can require hospitalization for aggressive pain management and hydration. Abdominal attacks have also been known to cause a significant increase in the patient’s white blood cell count, usually in the vicinity of 13-30,000. As the symptoms begin to diminish, the white count slowly begins to decrease, returning to normal when the attack subsides. As the symptoms and diagnostic tests are almost indistinguishable from an acute abdomen (e.g. perforated appendicitis) it is possible for undiagnosed HAE patients to undergo laparotomy (operations on the abdomen) or laparoscopy (keyhole surgery) that turns out to have been unnecessary.

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