Desmosome (desmoglein 1 and 3)
Adhesion & dermo-epidermal junction · Dsg1 superficial Dsg3 deep Pemphigus
Keratinocyte-to-keratinocyte adhesion plaque in which desmoglein and desmocollin cadherins bind across the intercellular space and link through plakoglobin and desmoplakin to the keratin cytoskeleton. Which desmoglein is attacked determines how deep the blister forms.
Traced from the start
- Stratum basale (germinativum)Stratum spinosumStratum granulosum
- Desmosome (desmoglein 1 and 3)
Detail
- Components
- Desmoglein 1 and 3 plus desmocollins in the membrane; plakoglobin and desmoplakin in the plaque, tying to K5/K14 or K1/K10 filaments
- Desmoglein distribution
- In skin, Dsg1 predominates superficially and Dsg3 deeply; in mucosa Dsg3 predominates throughout with little Dsg1
- Compensation rule
- A desmoglein can be neutralised without blistering where the other one is co-expressed — this explains every pemphigus phenotype
- Failure mode
- Acantholysis: keratinocytes separate from one another while remaining attached to the basement membrane, giving flaccid blisters and a positive Nikolsky sign
When it goes wrong
IgG against Dsg3 alone (mucosal pemphigus vulgaris)
Painful, non-healing oral erosions that often precede skin disease by months; mucosa blisters because Dsg1 cannot compensate there
IgG against Dsg3 plus Dsg1 (mucocutaneous pemphigus vulgaris)
Suprabasal acantholysis with flaccid skin blisters and erosions as well as mucosal disease; direct immunofluorescence shows intercellular IgG and C3 throughout the epidermis; treated with corticosteroids and rituximab
IgG against Dsg1 alone (pemphigus foliaceus)
Subcorneal split at the granular layer with scaly crusted erosions on the trunk, face and scalp, and no mucosal involvement because Dsg3 compensates in mucosa
Practise this structure
16 questions in the bank tagged Skin.
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