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).