Epidermolysis bullosa acquisita (EBA) blisters on the knees of a Hispanic male patient. EBA is a rare autoimmune disease of the connective tissues in the skin and mucosal membranes that presents in adulthood. In this condition, the collagen between the skin layers (the dermis and epidermis) is attacked and destroyed by the body's own immune system. This allows the layers to move across each other at the slightest pressure, resulting in blisters and painful sores.