Vesiculobullous Disorders
These conditions are characterized by the formation of blisters (vesicles or bullae). Distinguishing them requires understanding the level of cleavage within the skin (intraepidermal vs. subepidermal).
Key Autoimmune Blistering Diseases
| Condition | Cleavage Level | Key Features |
|---|---|---|
| Pemphigus Vulgaris | Intraepidermal | Flaccid bullae, mucosal involvement, +Nikolsky. |
| Bullous Pemphigoid | Subepidermal | Tense bullae, elderly, pruritic, -Nikolsky. |
| Dermatitis Herpetiformis | Subepidermal | Grouped vesicles, extensor surfaces, Celiac disease. |
Diagnostic Pearls
- Nikolsky Sign: Positive if the top layers of the skin slip away from the lower layers when rubbed; typical of Pemphigus Vulgaris.
- Immunofluorescence (IF): Gold standard. Pemphigus shows “fishnet” (intercellular) IgG; Bullous Pemphigoid shows “linear” IgG/C3 along the basement membrane zone.
High-Yield Exam Pearl:
- Pemphigus vs. Pemphigoid: Remember: Pemphigus = Positive Nikolsky and Profound mucosal involvement. Pemphigoid = Protected/tense bullae.
- Dermatitis Herpetiformis: Specifically responds to Dapsone therapy and a strict gluten-free diet.