Vesiculobullous (Blistering) Disorders
Blistering disorders are categorized based on the histological level of the skin split. This is the definitive way to differentiate between these autoimmune conditions.
Core Comparison: Intraepidermal vs. Subepidermal
| Disorder | Split Level | Autoantigen Target |
|---|---|---|
| Pemphigus Vulgaris | Intraepidermal | Desmoglein 1 & 3 (Desmosomes) |
| Bullous Pemphigoid | Subepidermal | BP180 / BP230 (Hemidesmosomes) |
| Dermatitis Herpetiformis | Subepidermal | Transglutaminase (anchoring fibrils) |
Key Clinical & Diagnostic Features
- Pemphigus Vulgaris: Flaccid bullae, erosions, positive Nikolsky sign, mucosal involvement. IF shows “Fishnet/Net-like” pattern.
- Bullous Pemphigoid: Tense bullae, usually in the elderly, negative Nikolsky sign, rare mucosal involvement. IF shows “Linear” band.
- Dermatitis Herpetiformis: Extremely pruritic, grouped vesicles on elbows/knees/sacrum. Strongly associated with Celiac disease (gluten sensitivity).
Exam Strategy for [mymedschool.org]:
- Mnemonic: Pemphigus = under the epidermis (intraepidermal); Pemphigoid = over the basement membrane (subepidermal).
- Treatment: Systemic corticosteroids are the gold standard for management of both Pemphigus and Pemphigoid.