Idiopathic angioedema is swelling due to a buildup of fluid in deeper layers of the skin with no known cause, according to WebMD. The swelling usually presents itself around the eyes and mouth, and sometimes around genitalia or the extremities.
Up to 20 percent of the population experiences angioedema at some point in their lives, states WebMD. Apart form idopathic angiodema, other types of angiodema include allergic angiodema, which is caused by allergies; drug-induced angiodema, which is caused by the use of certain medications; and genetic angiodema, which is caused by inherited genes. To diagnose angioedema, a doctor examines the affected area and performs allergy and blood tests.