Sonographic appearance of angioedema in local allergic reactions to insect bites and stings

Soft tissue infections and angioedema from insect bites and stings may be difficult to differentiate by inspection. We present sonographic findings of 4 cases of soft tissue swelling from insect bites and stings suggestive of angioedema. Sonographic features of soft tissue angioedema consist of thickened subcutaneous tissue layers with multiple linear, horizontal, striated, and hypoechoic lines following the tissue planes between soft tissue layers. In addition to the history and physical examination, sonographic findings may assist in differentiating between local allergic reactions and cellulitis in patients with insect bites and stings. Further study is warranted for clinical application.