1.6 Vesicle and bulla

Blister

Elevated, circumscribed, superficial, intra- or subepidermal fluid-filled lesion that contains clear fluid. Color: clear with transparent contents, may be haemorrhagic or purulent
Vesicle ≤ 1 cm, bulla > 1 cm

Often develop erosions and crusts
May heal with pigmentation, atrophy or rarely scarring
Associated with macules, secondary clouding= pustule
Bleeding = hemorrhagic vesicle or blister

Nikolsky sign may be positive with intraepidermal blisters
Widespread blistering may be an emergency situation

Infections: herpes simplex, varicella-zoster infection
Many diseases may become bullous: erysipelas, bullous impetigo, phototoxic reactions, phytophotodermatitis, acute contact dermatitis, dyshidrosis and pompholyx
Genetic disorders: epidermolysis bullosa group
Inflammatory disorders: Stevens-Johnson syndrome, toxic epidermal necrolysis
Autoimmune diseases: pemphigus vulgaris, bullous pemphigoid, Duhring’s disease

Loss of adhesion of epidermal keratinocytes
Loss of adhesion in basement membrane zone through physical trauma (burns, mechanical pressure)
Genetic defect (adhesion defects in epidermolysis bullosa)
Inflammation (autoimmune disorders, infections)