| • | autosomal dominant; (non-scarring) |
| • | most common form of epidermolysis bullosa |
| • | most patients have mutation in genes encoding keratins expressed in basal cells (keratins 5 and 14) |
| • | underlying mutation in keratin genes produces weakened cytoskeleton and mechanical fragility |
| • | cytolysis of basal cells (with resultant intraepidermal bullae) precipitated by trauma |
palmoplantar: (Weber-Cockayne)
| • | onset may be delayed until feet are subjected to heavy boots and shoes |
| • | ddx: pachyonychia congenita, tinea pedis, dishydrotic eczema, congenital syphilis |
generalized: (Kobner)
| • | bullae are induced by trauma |
| • | in infancy – occiput, back, legs (palms and soles relatively spared) |
| • | childhood – hands and feet, and friction points from clothing |
Herpetiform: (Dowling-Meara)
| • | two characteristic features: |
| • | widespread bullae with “herpetiform” grouping of bullae |
| • | with age, the development of confluent palmoplantar callosities, reminiscent of acquired keratoderma |
| • | ddx (for generalized and for Dowling-Meara): neonatal HSV, bacterial sepsis, IP, congenital syphilis, bullous impetigo, linear IgA disease |
| • | when H&E shows intraepidermal bullae, can further classify with electron microscopy: shows clumped tonofilaments in Dowling-Meara |
tonofilaments:
| • | a structural cytoplasmic protein |
| • | bundles made up of variable number of intermediate filaments, related proteins, keratin |
| • | found in all epithelial cells but particularly well developed in the epidermis |
intermediate filaments:
| • | a class of tough protein filaments (including keratin, desmin, vimentin) |
| • | so named because they are intermediate in thickness between actin filaments and microtubules |
| • | comprise part of the cytoskeleton of most eukaryotic cells |
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