What structural components of the epidermis are involved in blistering diseases?

In the epidermis, the keratinocytes are bound to each other by desmosomal complex. These complexes consist of the desmosome and the tonofilaments of the cytoplasm that are made of cytokeratins. In the upper stratum spinosum,  the tonofilaments are composed mainly of keratins 1 and 10. Congenital abnormalities in these keratins produce structural weakness between keratinocytes, producing a disease called congenital bullous ichthyosiform erythroderma (epidermolytic hyperkeratosis). Abnormalities in keratin types 5 (KRT5) and 14 (KRT14) in the basal cell layers lead to a mild blistering disease named epidermolysis bullosa simplex (EBS) (Fig. 1-4). Pemphigus is an acquired group of blistering diseases of the epidermis in which autoantibodies directed against antidesmosomal proteins produce damage to the desmosomes.


The skin diseases associated with antibodies and damage to the desmosomes and their characteristics are listed in Table 1-1.

Table 1-1. Diseases Associated with Antibodies and Damage to Desmosomes
	DISEASE INVOLVED		CLINICAL APPEARANCE AND LOCATION		MAIN DERMOSOMAL MOLECULES
	Pemphigus vulgaris		Oral and diffuse superficial flaccid blisters with ulcers		Desmogleins 1 and 3 (Dsg1 and 3) and plakoglobin
	Pemphigus foliaceus		Diffuse superficial blisters and crusting		Desmoglein 1 (Dsg1)
	Pemphigus vegetans		Vegetating, weeping lesions in the intertriginous areas		Desmoglein 3 (Dsg3)
	Pemphigus erythematosus		Butterfly eruption with blistering in malar areas		Desmoglein 3 (Dsg3)
	Paraneoplastic pemphigus		Diffuse erythema multiforme-like painful eruption		Desmoplakins 1 and 2 (Dsg1 and 2), BP antigen 1 (BP230), plectin, desmogleins 1 and 3 (Dsg1 and 3), envoplakin, periplakin
	IgA pemphigus		Pustular or vesiculopustular eruption		Desmogleins 1 and 3 (Dsg1 and 3), desmocollin 1