Bleb (medicine)

In medicine, a bleb is a blister (often hemispherical) filled with serous fluid. Blebs can form in a number of tissues due to different pathologies, including frostbitten tissues, and as a cause of spontaneous pneumothorax. In the lungs, a bleb is a collection of air within the layers of the visceral pleura. In ophthalmology, blebs may be formed intentionally in the treatment of glaucoma. In breasts a bleb is a milk blister (also known as blocked nipple pore, nipple blister, or “milk under the skin”).