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Epidermolysis bullosa simplex
Epidermolysis bullosa simplex (EBS) is a group of hereditary epidermolysis bullosa (HEB) disorders characterized by skin fragility resulting in intraepidermal blisters and erosions that occur either spontaneously or after physical trauma.
- Prevalence: 1-9 / 100 000
- Inheritance: Autosomal dominant or Autosomal recessive
- Age of onset: Infancy, Neonatal, Childhood, Adolescent
- ICD-10: Q81.0
- OMIM: -
- UMLS: C0079298
- MeSH: -
- GARD: 10752
- MedDRA: -
Reported prevalence ranges from 1/215,000 in the USA to 1/35,000 in Scotland.
Onset is usually at or shortly after birth, although blistering in localized EBS may not develop until late childhood or early adulthood. Along with localized or generalized blistering and erosions, sometimes showing characteristic patterns (herpetiform grouping), cutaneous features may include nail shedding and dystrophy, and, rarely, milia formation. Scarring is mostly absent or minimal (mild atrophic wrinkling and dyspigmentation). Other findings may include congenital absence of the skin, and localized or confluent keratoderma of the palms and soles. The commonest extracutaneous manifestation is blistering of the oral cavity. A variety of additional extracutaneous complications may occur and are age-dependent, with time of onset and cumulative risk of occurrence highly dependent on the EB subtype. Several subtypes exist based on the intraepidermal localization of blisters. In most, blisters occur in the basal layer of the epidermis (autosomal recessive EBS; Dowling-Meara type; Köbner type; EBS - muscular dystrophy; Ogna type; EBS - pyloric atresia; localized EBS; EBS with migratory circinate erythema; EBS with mottled pigmentation). However, 3 subtypes involve suprabasal blistering (EBS due to plakophilin deficiency, EBS superficialis, lethal acantholytic EB; see these terms).
EBS is caused by genetic mutations in specific genes depending on the subtype.
Diagnosis is based on determination of the epidermal level within which blisters develop following minor skin traction. Recommended techniques are immunofluorescence antigen mapping (IFM) and transmission electron microscopy (TEM) performed on a skin biopsy sample. Subtypes are then defined on the basis of the mode of transmission, IFM and TEM, and clinical presentation. Cutaneous findings are not reliable diagnostic markers.
Diagnosis is usually straightforward with little need for extensive differential diagnosis. However, in the neonatal period, in utero herpes simplex infection may be considered, especially if there is no family history of blistering disease or if clinical findings are atypical for EB. The differential diagnosis in neonates and small children may include congenital aplasia cutis, neonatal pemphigus, neonatal herpes gestationis, staphylococcal scalded skin syndrome, as well as incontinentia pigmenti, epidermolytic ichthyosis, linear IgA dermatosis, bullous pemphigoid, and bullous impetigo (see these terms).
Prenatal testing using fetal DNA from chorionic villi or amniotic fluid cells is possible if the causative gene is known and the pathogenetic mutation(s) identified.
Inheritance is either autosomal dominant or autosomal recessive, depending on the subtype. Correct diagnosis of EBS subtype is crucial to proper genetic counseling.
Management and treatment
Management is based on the avoidance of blistering by meticulous protective skin padding and appropriate life-style to avoid trauma, and prevention of secondary infection by careful wound care. Air-conditioning may help in preventing disease worsening in warm weather. Patients with EB subtypes with the highest risk of specific extracutaneous complications need to be monitored closely and appropriate measures implemented to prevent the affected tissues from becoming severely injured.
Prognosis is highly dependent on the subtype. Most patients have a normal life expectancy but significant morbidity and even early death may occur in some subtypes.