World's largest hand cyst? massive blister on hand
A blister may form when the skin has been damaged by friction or rubbing, heat, cold or chemical exposure. Fluid collects between the epidermis—the upper layer of the skin—and the layers below. This fluid cushions the tissue underneath, protecting it from further damage and allowing it to heal.
A blister is a small pocket of fluid within the upper layers of the skin, typically caused by forceful rubbing , burning, freezing, chemical exposure or infection. Most blisters are filled with a clear fluid called serum or plasma. However, blisters can be filled with blood or with pus .
The word lister entered English in the 14th century. It came from the Middle Dutch luyster, and was a modification of the Old French lostre which meant a leprous nodule—a rise in the skin due to leprosy. (source : wikipedia)