Sublamina densa

  • Contains anchoring fibrils, anchoring plaques, elastic microfibrils (without elastin), and linkin

Anchoring Fibril
  • Primary constituent is type VII collagen; appears larger than anchoring filaments and emanates perpendicularly down from lamina densa into papillary dermis
  • Connects lamina densa to anchoring plaques (type IV collagen) in dermal matrix
  • Intercalation with banded collagen fibrils of papillary dermis: forms fan-shaped clumps
   
 
Type VII collagen autoantibodies in both EB acquisita (EBA) and bullous SLE; type VII mutation in dystrophic EB (DEB)
 
   

Anchoring Plaque
  • Primary component is type IV collagen; site where anchoring fibrils attach from above and fibrillar collagen (type I and III) attach from below; electron-dense oval structures seen under lamina densa on EM
   
 
Table 1-4 Diseases Associated with Epidermal/Dermal Proteins
Protein
Associated Disease
Plectin
 
EBS with muscular dystrophy, paraneoplastic pemphigus (PNP)
α6β4 integrin
JEB with pyloric atresia, cicatricial pemphigoid (CP) - ocular
BPAG1
 
Bullous pemphigoid (BP), PNP
BPAG2
NC16A → BP, linear IgA bullous dermatosis (LABD), pemphigoid gestationis Carboxy terminus → CP
Laminin-332 (5)
 
JEB (Herlitz), CP (↑ risk of cancer)
Type VII collagen
Dystrophic EB (mutated), EBA, bullous SLE
Plakoglobin
 
Naxos disease
Desmocollin 1
Subcorneal pustular dermatosis (type of IgA pemphigus)
Desmoglein 1
 
Striate PPK, pemphigus foliaceous, pemphigus vulgaris (mucocutaneous), bullous impetigo, staphylococcal scalded skin syndrome (SSSS), PNP
Desmoglein 3
Pemphigus vulgaris (mucosal-dominant and mucocutaneous), PNP
Desmoglein 4
 
Monilethrix (autosomal recessive)
Desmoplakin 1/2
Carvajal syndrome, striate PPK, skin fragility/woolly hair syndrome, PNP
Plakophilin
 
Ectodermal dysplasia/skin fragility syndrome
Connexin 26
KID syndrome, Vohwinkel syndrome, PPK with deafness
Connexin 30
 
Hidrotic ectodermal dysplasia (HED)
Connexin 30.3/31
Erythrokeratoderma variabilis (EKV)
β-catenin
 
Pilomatricoma (multiple may be associated with myotonic dystrophy)
Loricrin
Vohwinkel (variant), progressive symmetric erythrokeratoderma
Filaggrin/KHG
 
Atopic dermatitis, ichthyosis vulgaris
Transglutaminase
TG3 → dermatitis herpetiformis, TG1 → lamellar ichthyosis