wheal and flare

https://doi.org/10.1351/goldbook.13784
Dermatological reaction at a skin site where an antigen is injected into an allergic individual. The reaction is characterized by a "flare" of erythema and a wheal produced by serum exuding into tissue, causing local edema.
Source:
PAC, 2012, 84, 1113. (IUPAC glossary of terms used in immunotoxicology (IUPAC Recommendations 2012)) on page 1260 [Terms] [Paper]