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EPIDERMOLYSIS BULLOSA

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Epidermolysis bullosa (EB) defines a group of rare inherited mechanobullous skin disorders that are characterized by skin fragility and bullae formation. There are three major categorizations of the disease: epidermolysis bullosa simplex (EBS), junctional epidermolysis bullosa (JEB), and dystrophic epidermolysis bullosa (DEB) with over 20 different phenotypes representing mutations in the genes of at least 18 structural proteins of the skin (in the epidermis, dermal–epidermal junction, or upper papillary dermis).

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INSIGHT Image not available.

Melanocytic nevi in children with recurrent blistering disorders may appear clinically atypical (large and dark with irregular borders) while having reassuring histological patterns.

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CLASSIFICATION

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Inherited EB can be classified based on phenotype and genotype, subdividing EB into types and subtypes as follows:

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  1. Epidermolysis bullosa simplex (EBS, with intraepidermal bullae)

    • Major subtypes:

      • EBS, localized (also known as EBS, Weber–Cockayne).

      • EBS, generalized intermediate (also known as EBS, Koebner).

      • EBS, generalized severe (also known as EBS, Dowling-Meara).

      • EBS with muscular dystrophy.

    • Minor subtypes:

      • EBS with mottled pigmentation.

      • Autosomal recessive EBS.

      • EBS, Ogna.

      • EBS with pyloric atresia.

      • EBS superficialis/suprabasal EBS.

  2. Junctional epidermolysis bullosa (JEB, with bullae cleavage plane at lamina lucida)

    • Major subtypes:

      • JEB, generalized severe (also known as JEB, Herlitz).

      • JEB, generalized intermediate (also known as JEB, non-Herlitz).

      • JEB with pyloric atresia.

    • Minor subtypes:

      • JEB inversa.

      • JEB localized.

      • JEB laryngo-onycho-cutaneous syndrome.

  3. Dystrophic epidermolysis bullosa (DEB, with bullae cleavage plane below lamina densa)

    • Major subtypes:

      • Dominant (D) DEB.

      • Recessive (R) DEB, generalized severe (also known as RDEB, Hallopeau– Siemens).

      • RDEB, generalized intermediate (also known as RDEB non-Hallopeau– Siemens).

    • Minor subtypes:

      • DDEB, pretibial.

      • DDEB pruriginosa.

      • RDEB inversa.

      • RDEB centripetalis.

      • DEB, transient bullous dermolysis of the newborn.

      • DEB, autosomal, dominant/autosomal, recessive heterozygote.

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EPIDERMOLYSIS BULLOSA SIMPLEX

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EBS is typically an autosomal dominantly inherited, typically nonscarring, blistering disorder which results from cleavage within or above the basal cell layer of the epidermis.

There are three major subtypes of EBS which have a mutation in the genes coding for keratin 5 or keratin 14 which are found in the basal keratinocyte, and a fourth major subtype associated with muscular dystrophy which arises from mutations in the gene encoding the protein plectin:

  • Major subtypes:

    • EBS, localized (also known as EBS, Weber–Cockayne).

    • EBS, generalized intermediate (also known as EBS, Koebner).

    • EBS, generalized severe (also known as EBS, Dowling-Meara).

    • EBS with muscular dystrophy.

There are more rare autosomal recessive generalized EBS forms with a variety of causative mutations:

  • Minor subtypes:

    • EBS with mottled pigmentation—mutation in keratin 5.

    • Autosomal recessive EBS—mutation in keratin 5 or 14.

    • EBS, Ogna—mutation in plectin.

    • EBS with pyloric atresia—mutation in plectin.

    • EBS superficialis (unknown genetic defect, intraepidermal blister just beneath the granular layer, may be a clinical variant of another form of EB).

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SYNONYM Epidermolytic EB.

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EPIDEMIOLOGY
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AGE

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  • Major subtypes:

    • EBS, localized (Weber–Cockayne): Blisters may appear in first 2 years of life. It can also ...

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