Skin-nontumor / Clinical dermatology
Blistering disorders
Epidermolysis bullosa (EB)

Author: Mowafak Hamodat, M.D., MB.CH.B, MSc., FRCPC (see Authors page)

Revised: 14 June 2016, last major update July 2011

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PubMed Search: Epidermolysis bullosa (EB)

Cite this page: Epidermolysis bullosa (EB). PathologyOutlines.com website. http://pathologyoutlines.com/topic/skinnontumorepidermolysisbullosa.html. Accessed December 7th, 2016.
Definition / General
  • Rare genetic blistering disorder (incidence of 8 - 19 per million) with cleavage in dermis, lower epidermis or at dermoepidermal junction
  • Classified as EB simplex, junctional EB, dystrophic EB and Kindler syndrome, based on level of tissue separation within the cutaneous basement membrane zone (Orphanet J Rare Dis 2010;5:12)
  • Also classified and subclassified based on clinical, electron microscopic, immunohistochemical and genotypic features (J Am Acad Dermatol 2008;58:931, Orphanet J Rare Dis 2010; 5: 12)

  • EB Simplex: intraepidermal tissue separation; degeneration of basal cell layer causes clinical bullae; usually due to dominant mutations in keratin 14 or keratin 5 (J Clin Invest 2009;119:1784)
  • Junctional: blisters within lamina lucida, skin appears normal
  • Dystrophic: blisters are sub-lamina densa; dominant or recessive
  • Kindler syndrome: blisters at multiple levels (intra-lamina lucida and sub-lamina densa)
Etiology
  • Defects in Keratin K5 / K14 filament network architecture cause basal keratinocytes to become fragile and account for their trauma-induced rupture
Diagrams / Tables

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Normal epidermis and components

Level of disruption in EB subtypes

Clinical Features
  • Blisters form shortly after birth due to pressure, rubbing or trauma
  • Blisters cause scarring or milia on dorsum of hands, elbows and knees and oromucosal lesions
  • EB Simplex-Dowling Meara: associated with marked morbidity; may cause death during early infancy; exhibits intact vesicles or small blisters in a grouped or arcuate (curved) configuration
  • Junctional EB: characterized by enamel hypoplasia, with pitting of some or all of the tooth surfaces
  • Junctional EB-Herlitz subtype: severe symptoms; presents at birth and involves all skin surfaces with exuberant granulation tissue of skin and possibly upper airway
  • Recessive dystrophic EB: subtypes are severe generalized (formerly Hallopeau-Siemens), non-Hallopeau-Siemens and inverse; each arises at birth; severe generalized is "one of the most devastating multiorgan genetically transmitted diseases of mankind"; has generalized blistering at birth, progressive and often mutilating scarring of skin, corneal blisters or scarring, profound growth retardation, multifactorial anemia, failure to thrive, esophageal strictures and debilitating hand and foot deformities

  • Diagnosis: usually requires focused lab testing, such as transmission EM (“gold standard”), immunofluorescence antigen mapping or immunohistochemical staining with EB-specific monoclonal antibodies
Clinical Images

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Typical noninflammatory blister

EB simplex-blistered foot of infant

EB simplex, generalized, with Dowling-Meara variant

Junctional EB: marked pitting of enamel

Junctional EB

Junctional EB-Herlitz subtype: exuberant granulation tissue on child's neck



Dominant dystrophic EB-milia arising within erythematous patch

Generalized dominant dystrophic EB: atrophic scarring and postinflammatory hypopigmentation on extremity

Generalized dominant dystrophic EB: hypertrophic scarring

Generalized dominant dystrophic EB: dystrophy of all 20 nails

Recessive dystrophic EB



Severe generalized recessive dystrophic EB: partial mitten deformity of child's hand

Severe generalized recessive dystrophic EB: complete mutilating deformities of hands of young adult

Congenital absence of skin in neonate with Bart's syndrome (not specific for any EB subtype)

Micro Description
  • Subepidermal blister with variable inflammation
  • Superficial dermis is fibrotic (Type IV collagen positive)
Micro Images

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EB simplex: intact stratum corneum and upper epidermis, with vesicle formation in the lower epidermis at the basal layer caused by degeneration of individual epidermal cells

Dystrophic EB: pretibial lesion

Positive Stains
Electron Microscopy Description
Electron Microscopy Images

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EB simplex: epidermal basal keratinocytes