Epidermolysis Bullosa

Epidermolysis bullosa (EB) is a collection of disorders in which inherited defects in various skin structural elements result in mechanical fragility of the skin and blister formation from birth. Any site with an epithelial cell layer can be affected in EB. There are three major forms of epidermolysis bullosa, distinguished on the basis of the ultrastructural level at which blister formation occurs as observed on transmission electron microscopy, each with several subtypes. There are a number of minor subtypes, as well.

**Major EB Subtypes**
*EB Type*	Affected Protein/Structure	Level of Blister	Mode of inheritance	*Special Features*
Epidermolysis Bullosa Simplex (EBS)
EBS, Weber-Cockayne (EBS-WC)	Keratins 5 and 14/Keratins	Lower basilar keratinocyte	Autosomal dominant	Limited to sole of foot and sides of toes, sometimes hands; sometimes knees when infants start to crawl; rarely other areas.
EBS, Dowling-Meara (EBS-DM)	Keratins 5 and 14/Keratins	Lower basilar keratinocyte	Autosomal dominant	Grouped (herpetiform) lesions in arcuate pattern; palmoplantarkeratoderma
EBS, Koebner (EBS-K)	Keratins 5 and 14/Keratins	Lower basilar keratinocyte	Autosomal dominant
EBS with muscular dystrophy (EBS-MD)	Plectin/Hemidesmosome	Beneath granular layer of epidermis	Autosomal recessive
Junctional Epidermolysis Bullosa (JEB)
JEB, Herlitz (JEB-H)	Laminin-5 and Type XVII collagen/Anchoring filaments and hemidesmosome	Intralamina lucida	Autosomal recessive	Excessive granulation tissue.
JEB, non-Herlitz (JEB-nH)	Laminin-5 and Type XVII collagen/Anchoring filaments and hemidesmosome	Intralamina lucida	Autosomal recessive
JEB with pyloric atresia (JEB-PA	α6β5 integrin/Hemidesomosome	Intralamina Lucida	Autosomal recessive
Dystrophic Epidermolysis Bullosa (DEB)
Dominant DEB (DDEB)	Type VII collagen/anchoring fibrils	Sublamina densa	Autosomal dominant
Recessive DEB, Hallopeau-Siemens (RDEB-HS)	Type VII collagen/anchoring fibrils	Sublamina densa	Autosomal recessive
Recessive DEB, non-Hallopeau-Siemens (RDEB-nHS)	Type VII collagen/anchoring fibrils	Sublamina densa	Autosomal recessive

Scarring can be a prominent feature of the disease, especially in those forms that affect the basement membrane. Nail dystrophy, scarring alopecia, and miia are often present.

Outside of childhood, an inherited blistering disorder is usually epidermolysis bullosa. In the newborn period, in the absence of family history, other autoimmune bullous diseases must be considered, such as bullous pemphigoid, pemphigus vulgaris, linear IgA bullous dermatosis and epidermolysis bullosa acquisita. Infectious diseases, including herpes simplex virus, staphylococcal scalded skin syndrome and bullous impetigo are always possibilities.

Epidermolysis bullosa can be diagnosed by either scanning electron microscopy, immunohistochemical staining of fresh frozen skin specimens, or by several molecular biology assays.

There is no specific treatment for epidermolysis bullosa. Management is directed toward prevention of new blister formation and on the prevention and treatment of complications.

Death from infection has become less common due to better wound care. Squamous cell carcinoma often arises in injured skin, especially in RDEB-HS. The risk of developing at least one squamous cell carcinoma in RDEM-HS was reported to be 6%, 22%, 40%, 53% and 77% by ages 20, 25, 30, 35 and 60 years, respectively.