Differentials
Epidermolytic hyperkeratosis (bullous congenital ichthyosiform erythroderma)
SIGNS / SYMPTOMS
Blistering during early infancy may be similar to that of EB, although usually the skin is not markedly fragile.
The oral cavity is uninvolved.
In older children, arm skin develops characteristic carpet-like thickening and scale, most pronounced within the antecubital fossae.
INVESTIGATIONS
Transmission electron microscopy demonstrates intraepidermal dysadhesion of keratinocytes.
Congenital porphyrias
SIGNS / SYMPTOMS
Some porphyrias may, like some types of EB, be associated with vesiculation or blistering of the skin with milia, although mechanical fragility is usually absent.
In one type, erythropoietic protoporphyria, a stinging or burning sensation, particularly on the face, follows brief (i.e., minutes) exposure to sunlight.
With time, cobblestone-like changes and scarring develop on the face.
INVESTIGATIONS
Specific urinary porphyrin levels are elevated in patients who have a congenital form of porphyria.
Cutaneous absence of skin (aplasia cutis)
SIGNS / SYMPTOMS
Infants with aplasia cutis, in the absence of EB, usually have wedge-shaped depressed skin areas on the scalp.
Blisters and mechanical fragility are absent.
In contrast, when aplasia cutis occurs in a patient with EB (Bart syndrome), these lesions are usually on the feet, ankles, and wrists.[48]
INVESTIGATIONS
No differentiating test is usually performed.
A skin biopsy may be obtained to definitively confirm the diagnosis, but clinical findings alone are usually adequate.
Immunobullous diseases (e.g., pemphigoid, pemphigus, EB acquisita, linear IgA dermatosis)
SIGNS / SYMPTOMS
Rare in newborns and infants.
Most lack clinically significant mechanical fragility or any of the other skin findings (milia, nail dystrophy, scarring) that are characteristic of inherited EB.
Other family members are usually unaffected.
INVESTIGATIONS
Direct immunofluorescence is positive in all immunobullous diseases, with patterns indicative of specific diseases.
Bullous pemphigoid skin has IgG and C3 along the dermo-epidermal junction (DEJ).
Linear IgA dermatosis (chronic bullous dermatosis of childhood) has only IgA in linear array along the DEJ.
EB acquisita has multiple immunoglobulins and C3 along the DEJ.
Pemphigus has IgG and C3 in an intercellular pattern within the epidermis.
Sera from these patients contain specific autoantibodies having identical binding patterns on normal human skin or monkey esophagus testing substrate, or can be identified by specific ELISA tests now available commercially.
Congenital or acquired viral infections (varicella, herpes simplex)
SIGNS / SYMPTOMS
More commonly vesicular rather than bullous.
Not associated with other skin findings typically seen in EB.
The skin is not mechanically fragile.
Maternal history may be positive for infection during pregnancy.
INVESTIGATIONS
Tzanck preparation of the blister fluid demonstrates multinucleated giant cells.
Characteristic cytopathic changes are seen in viral cultures incubated with blister fluid.
Bullous impetigo
SIGNS / SYMPTOMS
Uncommon in early infancy.
Usually a very localized eruption.
Tense blisters arise on reddened skin.
Typical sites include the groin, trunk, and umbilicus.
Ruptured lesions are covered with honey-colored crusting.
The skin is not mechanically fragile.
INVESTIGATIONS
Bacterial culture of blister fluid reveal Staphylococcus aureus.
Staphylococcal scalded skin syndrome
SIGNS / SYMPTOMS
Occurs in infants and small children.
Usually adjacent to a site of skin infection, such as the ear canal or nares.
Erosions arise on reddened skin, most notably on the face and upper chest.
Blisters are conspicuously absent.
The surrounding skin appears scalded and the surface can be easily peeled away with gentle lateral traction.
INVESTIGATIONS
Skin biopsy reveals superficial cleavage just beneath the level of the stratum corneum.
S aureus can be cultured from the adjacent infected skin.
Bullous mastocytosis
SIGNS / SYMPTOMS
Localized tense blisters or vesicles arise on normal-appearing skin or on firm dermal plaques or nodules.
Lesions may sometimes be induced by gentle stroking of the skin (Darier sign).
Milia are absent.
The lesions are usually pruritic.
Family history is negative.
INVESTIGATIONS
Skin biopsy reveals dense collections of mast cells within the dermis, as well as within the blister cavity.
Other genodermatoses (e.g., pachyonychia congenita, Hay-Wells syndrome, acrodermatitis enteropathica, ichthyosis bullosa of Siemens, and incontinentia pigmenti)
SIGNS / SYMPTOMS
Very rarely these diseases may present with vesicles or blisters.
Each of these, however, has other clinical findings that permit them to be readily distinguished from inherited EB.
INVESTIGATIONS
Each of these entities has distinguishing skin biopsy findings.
Low serum zinc levels are characteristic of acrodermatitis enteropathica.
Lichen planus
SIGNS / SYMPTOMS
The nonbullous skin lesions in patients with 2 rare dystrophic EB subtypes (pretibial dystrophic EB [DEB]; DEB pruriginosa) may resemble those of lichen planus (violaceous papules or small plaques).
Buccal white patches (Wickham striae) typical of lichen planus, not EB.
Patients with lichen planus often have associated nail changes (pterygium).
INVESTIGATIONS
Skin biopsy reveals distinctive routine histologic features, including band-like (lichenoid) infiltrate of lymphocytes along the DEJ, enlargement of the granular layer within the epidermis, and saw-toothed epidermal hyperplasia.
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