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Vesiculobullous Disorders

»	What is the difference between a vesicle and a bulla?
»	How are the bullous diseases defined?
»	What things cause vesicles and bullae?
»	How do you approach a patient who presents with an acute onset of a vesiculobullous eruption?
»	Which skin findings are helpful in evaluating a patient with blisters?
»	Do particular vesiculobullous diseases occur in characteristic distributions?
»	Which tests are most useful in evaluating vesiculobullous diseases?
»	How should a skin biopsy of a vesiculobullous eruption be performed?
»	When are special tests necessary to diagnose blistering diseases of the skin?
»	How are specimens obtained for direct immunofluorescence?
»	For which vesiculobullous diseases are indirect immunofluorescence helpful?
»	List the most common blistering diseases due to external agents.
»	Name examples of drugs that can cause vesiculobullous eruptions.
»	What is epidermolysis bullosa?
»	Describe the other genetic blistering diseases.
»	List the vesiculobullous diseases caused by metabolic disorders.
»	Describe the clinical findings in bullous diabeticorum.
»	What is the cause of pellagra?
»	What is the difference between porphyria cutanea tarda and pseudoporphyria?
»	What are the necrolytic erythemas?
»	What is the difference between bullous pemphigoid and cicatricial pemphigoid?
»	How do pemphigus vulgaris and pemphigus foliaceus differ?
»	Linear IgA bullous dermatosis occurs in two different clinical situations. What are they?
»	Describe the clinical findings in dermatitis herpetiformis.
»	Does herpes gestationis have anything to do with herpes viruses?
»	What is bullous systemic lupus erythematosus?
»	What is epidermolysis bullosa acquisita?

How are the bullous diseases defined?

Fig. 10.1 Structural components of the basement membrane zone. (Courtesy of Nicole L. Brevik.)

Bullous diseases are characterized by blisters. Blisters are defined as circumscribed skin lesions containing fluid. They may arise at various depths in the epidermis and dermis and are sometimes classified on the basis of the depth of skin involved. One broad classification divides blisters into those that develop within the epidermis (intraepidermal) versus those that develop below the epidermis (subepidermal) (Table 10-1). Some blistering disorders develop because of autoantibodies directed against a component of the epidermis or basement membrane zone, or they develop because of structural defects of these components. Refer to Fig. 10-1 for the location of these components in normal skin as they are discussed during questions.

Table 10-1. Intraepidermal versus Subepidermal Blisters
	INTRAEPIDERMAL BLISTERS	SUBEPIDERMAL BLISTERS
	Allergic contact dermatitis (spongiotic) Bullous dermatophyte infection (spongiotic) Herpes simplex (acantholytic) Herpes zoster/varicella (intraepidermal acantholytic) Bullous impetigo (subcorneal) Miliaria crystallina (subcorneal) Epidermolysis bullosa simplex (mechanobullous) Pemphigus vulgaris (suprabasilar acantholytic) Pemphigus foliaceus (subcorneal acantholytic) Paraneoplastic pemphigus Hailey-Hailey disease (intraepidermal acantholytic) Incontinentia pigmenti (spongiotic) Bullous congenital erythroderma (mechanobullous)	Porphyria cutanea tarda Bullous pemphigoid Cicatricial pemphigoid Dermatitis herpetiformis Linear IgA bullous dermatosis Bullous systemic lupus erythematosus (SLE) Epidermolysis bullosa acquisita Dystrophic epidermolysis bullosa Junctional epidermolysis bullosa Anti–p200 pemphigoid Anti–p105 pemphigoid