Vesiculobullous Disorders

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Chapter 646 Vesiculobullous Disorders

Many diseases are characterized by vesiculobullous lesions; they vary considerably in cause, age of onset, and pattern. The morphology of the blister often provides a visual clue to the location of the lesion within the skin. Blisters localized to the epidermal layers are thin-walled, relatively flaccid, and easily ruptured. Subepidermal blisters are tense, thick-walled, and more durable. Biopsies of blisters can be diagnostic because the level of cleavage within the skin and associated findings, such as the nature of the inflammatory infiltrate, are characteristic for a particular disorder. Other diagnostic procedures, such as immunofluorescence and electron microscopy, can often help distinguish vesiculobullous disorders that have nearly identical histopathologic findings (Table 646-1).


Acrodermatitis enteropathica IE Zn level
Bullous impetigo GL Smear, culture
Bullous pemphigoid SE (junctional) Direct and indirect immunofluorescence studies
Candidosis SC KOH preparation, culture
Dermatitis herpetiformis SE Direct immunofluorescence studies
Dermatophytosis IE KOH preparation, culture
Dyshidrotic eczema IE Routine histopathology
EB—simplex IE Electron microscopy; immunofluorescence mapping
EB of the hands and feet IE Electron microscopy; immunofluorescence mapping
Junctional EB (letalis) SE (junctional) Electron microscopy; immunofluorescence mapping
Recessive dystrophic EB SE Electron microscopy; immunofluorescence mapping
Dominant dystrophic EB SE Electron microscopy; immunofluorescence mapping
Epidermolytic hyperkeratosis IE Routine histopathology
Erythema multiforme SE Routine histopathology
Erythema toxicum SC, IE Smear for eosinophils
Incontinentia pigmenti IE
Insect bites IE Routine histopathology
Linear IgA dermatosis SE Direct immunofluorescence studies
Mastocytosis SE Routine histopathology
Miliaria crystallina IC Routine histopathology
Neonatal pustular melanosis SC, IE Smear for cells
Pemphigus foliaceus GL Direct and indirect immunofluorescence studies
Tzanck smear
Pemphigus vulgaris Suprabasal Direct and indirect immunofluorescence studies
Tzanck smear
Scabies IE Scraping
Staphylococcal scalded skin syndrome GL Routine histopathology
Toxic epidermal necrolysis SE Routine histopathology
Viral blisters IE

EB, epidermolysis bullosa; GL, granular layer; IC, intracorneal; IE, intraepidermal; KOH, potassium hydroxide; SC, subcorneal; SE, subepidermal.

646.1 Erythema Multiforme

Clinical Manifestations

EM has numerous morphologic manifestations on the skin, varying from erythematous macules, papules, vesicles, bullae, or urticaria-appearing plaques to patches of confluent erythema. The eruption appears most commonly in patients between the ages of 10 and 40 yr and usually is asymptomatic, although a burning sensation or pruritus may be present. The diagnosis of EM is established by finding the classic lesion: doughnut-shaped, target-like (iris or bull’s-eye) papules with an erythematous outer border, an inner pale ring, and a dusky purple to necrotic center (Figs. 646-1 and 646-2).


Figure 646-1 Early fixed papules with a central dusky zone on the dorsum of the hand of a child with erythema multiforme due to herpes simplex virus.

(From Weston WL, Lane AT, Morelli J: Color textbook of pediatric dermatology, ed 3, St Louis, 2002, Mosby, p 156.)


Figure 646-2 “Target” or “iris” lesions with characteristic central dusky zone on palms of a child with erythema multiforme due to herpes simplex virus.

(From Weston WL, Lane AT, Morelli J: Color textbook of pediatric dermatology, ed 3, St Louis, 2002, Mosby, p 156.)

EM is characterized by an abrupt, symmetric cutaneous eruption, most commonly on the extensor upper extremities; lesions are relatively sparse on the face, trunk, and legs. The eruption often appears initially as red macules or urticarial plaques that expand centrifugally to form lesions up to 2 cm in diameter with a dusky to necrotic center. Lesions of a particular episode typically appear within 72 hr and remain fixed in place. Oral lesions may occur with a predilection for the vermilion border of the lips and the buccal mucosa, but other mucosal surfaces are spared. Prodromal symptoms are generally absent. Lesions typically resolve without sequelae in about 2 wk; progression to Stevens-Johnson syndrome does not occur. EM may manifest initially as urticarial lesions, but unlike urticaria, a given lesion of EM does not fade within 24 hr.

646.2 Stevens-Johnson Syndrome


Mycoplasma pneumoniae is the most convincingly demonstrated infectious cause of Stevens-Johnson syndrome. Drugs, particularly sulfonamides, nonsteroidal anti-inflammatory agents, antibiotics, and anticonvulsants, are the most common precipitants of Stevens-Johnson syndrome and toxic epidermal necrolysis. HLA-B*1502 and HLA-B*5801 have been implicated in the development of these two disorders in Han Chinese patients receiving carbamazepine and in Japanese patients receiving allopurinol, respectively.

Clinical Manifestations

Cutaneous lesions in Stevens-Johnson syndrome generally consist initially of erythematous macules that rapidly and variably develop central necrosis to form vesicles, bullae, and areas of denudation on the face, trunk, and extremities. The skin lesions are typically more widespread than in EM and are accompanied by involvement of two or more mucosal surfaces, namely the eyes, oral cavity, upper airway or esophagus, gastrointestinal tract, or anogenital mucosa (Fig. 646-3). A burning sensation, edema, and erythema of the lips and buccal mucosa are often the presenting signs, followed by development of bullae, ulceration, and hemorrhagic crusting. Lesions may be preceded by a flu-like upper respiratory illness. Pain from mucosal ulceration is often severe, but skin tenderness is minimal to absent in Stevens-Johnson syndrome, in contrast to pain in toxic epidermal necrolysis. Corneal ulceration, anterior uveitis, panophthalmitis, bronchitis, pneumonitis, myocarditis, hepatitis, enterocolitis, polyarthritis, hematuria, and acute tubular necrosis leading to renal failure may occur. Disseminated cutaneous bullae and erosions may result in increased insensible fluid loss and a high risk of bacterial superinfection and sepsis. New lesions occur in crops, and complete healing may take 4-6 wk; ocular scarring, visual impairment, and strictures of the esophagus, bronchi, vagina, urethra, or anus may remain. Nonspecific laboratory abnormalities in Stevens-Johnson syndrome include leukocytosis, elevated erythrocyte sedimentation rate, and, occasionally, increased liver transaminase levels and decreased serum albumin values. Toxic epidermal necrolysis is the most severe disorder in the clinical spectrum of the disease, involving considerable constitutional toxicity and extensive necrolysis of the mucous membranes and > 30% of the body surface area (Fig. 646-4).


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