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What is Etiology of Quincke's edema: and explain in detail?
Common causes of Angio or Quincke’s edema or Giant urticaria

Allergic angioedema due to mast cell degranulation that leads to histamine release. Seen in IgE mediated hypersensitivity reactions.
Use of ACE inhibitors, which increase the levels of bradykinin and this form of angioedema usually arises within hours of initial use of the drug.
Hereditary in which there is reduction of an inhibitor, that prevents the transformation of C1 to C1 esterase that cleaves C4 and C2 and results in angioedema.
Due to presence of high levels of antigen-antibody complexes (Eg: LE patients).

Ref: Shafer's textbook of oral pathology 7th edition page 675