Pathophysiology

Epidermolysis Bullosa (EB) is classified into 3 major categories:

1.   Epidermolysis Bullosa Simplex (EBS): intraepidermal skin separation

2.   Junctional Epidermolysis Bullosa (JEB): skin separation in lamina lucida or central BMZ

3. Dystrophic Epidermolysis Bullosa (DEB): sublamina densa BMZ separation

These types differ not only phenotypically and genotypically but more importantly by the site of ultrastructural disruption or cleavage.

EB Simplex (EBS) occurs in the outer layer of the skin- further subdivided based on whether blister arise within the basal (i. e. lowermost) or suprabasal (i.e. upper) layer of the ‘Epidermis’.

Junctional EB (JEB) and Dystrophic EB ((DEB) patients develop their blisters within the lamina lucida and sub-lamina densa of the skin basement membrane zone (BMZ) (“Dermoepidermal Junction”) respectively.

Researchers have proposed a new category termed ‘Hemidesmosomal Epidermolysis Bullosa (HEB)’ which produces blistering at the hemidesmosomal level in the most superior aspect of the BMZ.