Types of epidermolysis bullosa Four major epidermolysis bullosa types are defined, based on the level or levels of tissue cleavage and bullae formation (see figure Skin cleavage levels in epidermolysis bullosa) in relation to the skin's basement membrane zone (dermal-epidermal junction): Epidermolysis bullosa simplex: Epidermis Junctional epidermolysis bullosa: Lamina lucida of the basement membrane zone Dystrophic epidermolysis bullosa: Sublamina densa (uppermost dermis, just below the lamina densa of the basement membrane zone) Kindler syndrome: Variable—intraepidermal or subepidermal Skin cleavage levels in epidermolysis bullosa In this figure, the basement membrane zone is disproportionately enlarged to display its layers.