Pediatric emergency medicine trisk 325

membrane zone. First-line therapy is dapsone. Other therapies include
prednisone, sulfapyridine, colchicine, erythromycin, and topical steroids. The
condition tends to spontaneously remit over months to years but occasionally can
be chronic.

Bullous Pemphigoid
Bullous pemphigoid is a rare autoimmune blistering disorder that may develop as
early as the newborn period and is due to autoantibodies to one of two
hemidesmosomal proteins, BP 230 and BP 180, which help to maintain dermal–
epidermal attachment. Primary lesions include diffuse, large, tense, clear, or
hemorrhagic bulla on a noninflammatory or erythematous base, although
urticarial lesions occasionally predominate. Common locations include forearms,
abdomen, thighs, genitals, palms, and soles. The striking acral involvement is
more common in infancy and may help to distinguish clinically from other
autoimmune blistering diseases. Mucosal involvement may be seen. Pruritus is
common and may be severe.
Diagnosis is confirmed by biopsy of a vesicle demonstrating a subepidermal
bulla with a predominantly eosinophilic infiltrate, and DIF from perilesional skin
revealing linear deposition of immunoglobulin G (IgG) and C3. Enzyme-linked
immunosorbent assay (ELISA) of BP 230 and 180 is commercially available as is
indirect immunofluorescence testing for autoantibodies in the blood. BP may also
be initially confused with bullous impetigo. The mainstay of treatment is oral
corticosteroids, and the disease lasts an average of 1 year.

Dermatitis Herpetiformis
DH presents as symmetric, intensely pruritic, crusted papules, papulovesicles, and
urticarial plaques overlying extensor surfaces of the elbows and knees, posterior
neck, scalp, and buttocks. Children with DH have gluten-sensitive enteropathy,
however many are asymptomatic. Only about 10% of patients with a diagnosis of
celiac disease will present with the classic eruption of DH.

TABLE 67.3
AUTOIMMUNE BULLOUS DISORDERS OF CHILDHOOD
Chronic bullous
disease of
childhood
Type of lesions

Distribution

Bullous
pemphigoid

Large, tense, clear Large, tense
Grouped
bullae; annular
bullae
papulovesicles,
plaques with
bullae, or
active vesicular
urticarial
borders
lesions
Scalp, lower
Trunk and flexor Back, buttocks,
trunk, genitals,
surfaces of
scalp, extensor
buttocks, inner

extremities
surface of
thighs
extremities,
often
symmetric
None to severe
Mild
Intense
Occasionally
Yes
No

Pruritus
Mucous membrane
involvement
Duration
Months to years
Months to years
Immunofluorescence + or −
+
Linear IgA
Linear IgG on
basement
basement
membrane (+
membrane (+
circulating IgA)
circulating
IgG)

Treatment

Dermatitis
herpetiformis

Dapsone >
Corticosteroids
Corticosteroids

Months to years
+
Granular IgA at
tips of dermal
papilla of
uninvolved
perilesional
skin
Dapsone >
Sulfapyridine

Diagnosis is confirmed by biopsy of a papule or vesicle showing a
predominately neutrophilic infiltrate focused at the tip of the dermal papillae. DIF
reveals granular IgA deposition at the dermal papillae. Diagnosis may also be
made by circulating serum IgA antibody to tissue transglutaminase in the blood.
IgA levels should be checked as IgA deficiency may lead to a false-negative test.


Additional diagnostic tests often included in a celiac panel include
antiendomysial antibodies and antigliadin antibodies. Patients with DH should
undergo endoscopy to assess for clinical evidence of gluten-sensitive enteropathy.

Treatment includes dapsone, which leads to spontaneous remission of DH in 24 to
48 hours. Strict adherence to a gluten-free diet is recommended and may obviate
the need for dapsone.
For comparison of the above autoimmune bullous diseases, see Table 67.3 .

Systemic Lupus Erythematosus
Although not characteristic, widespread tense, bullous lesions can occur in
systemic lupus erythematosus (SLE), usually in sun-exposed areas. Multisystem
involvement suggests the diagnosis. Laboratory confirmation, which may include
a skin biopsy and lupus band test, in conjunction with the complete clinical
picture, is necessary for diagnosis.

OTHER BULLOUS ERUPTIONS THAT MAY BE CONFUSED
WITH AUTOIMMUNE BLISTERING DISEASES
Many times, the appearance of a rash is so characteristic that a diagnosis becomes
obvious. Such is the case with the conditions listed below, which are discussed in
more detail in their respective chapters but are mentioned here for completeness
when considering a vesiculobullous eruption.
Linear or geometric areas of vesiculation are the best clues to the presence of
allergic contact dermatitis (see Chapter 65 Rash: Atopic/Contact Dermatitis and
Photosensitivity ). The shape of the dermatitis provides the information that helps
identify the offending agent. A history of playing in a shrubbed area, camping,
hiking, or being near burning leaves is helpful. Because children brush against
poison ivy leaves, vesicles often are in a line and on exposed surfaces (e.g., the
face, extremities). A round group of vesicles on the back of the wrist would point
to contact sensitivity to nickel contained in the metal case of a wristwatch.
Dermatomal distribution of vesicles or bullae usually indicates the presence of
herpes zoster. On rare occasions, in infants, the same dermatomal appearance may
represent zosteriform herpes simplex infections. Viral cultures, rapid slide tests
using monoclonal antibodies, or more recently, polymerase chain reaction tests

are utilized to differentiate herpes simplex from herpes zoster.
Target or iris lesions are pathognomonic of erythema multiforme. The lesion
has a dusky center that may blister and has successive bright red bordering rings.
At times, a doughnut-shaped blister occurs ( Fig. 67.7 ). This contrasts with
annular urticaria, in which incompletely round (arcuate or polycyclic) wheals are
observed and individual lesions typically resolve within less than 24 hours (see


Chapter 68 Rash: Drug Eruptions ). CBDC may be confused with erythema
multiforme as discussed above.

FIGURE 67.7 Erythema multiforme on the hand with large, target-shaped lesions with central
blistering due to recurrent herpes simplex labialis.