When does bullae occur?
Score: 4.2/5 (26 votes) A bulla is a fluid-filled sac or lesion that appears when fluid is trapped under a thin layer of your skin. It's a type of blister. Bullae (pronounced as “bully”) is the plural word for bulla. To be classified as a bulla, the blister must be larger than 0.5 centimeters (...