Bullous Pemphigoid
Bullous Pemphigoid (BP) is the most common autoimmune blistering disease, typically affecting the elderly. It is characterized by autoantibodies against hemidesmosomes (specifically BP180 and BP230) at the dermo-epidermal junction.
Clinical Presentation
- Prodrome: May present with an intensely pruritic, urticarial, or eczematous eruption weeks or months before bullae appear.
- Bullae: Tense, firm, fluid-filled blisters; often found on flexural surfaces and the trunk.
- Nikolsky Sign: Negative; because the cleavage is subepidermal, the blister roof is reinforced by the entire epidermis.
Diagnostic Criteria
| Test | Finding |
|---|---|
| Histopathology | Subepidermal bulla with eosinophilic infiltrate. |
| Immunofluorescence | Linear IgG and C3 deposits along the basement membrane zone. |
High-Yield Exam Pearl:
- Comparison: Unlike Pemphigus Vulgaris, BP usually spares the oral mucosa.
- Management: High-potency topical corticosteroids (e.g., clobetasol) are often first-line; systemic steroids or immunosuppressants are reserved for extensive disease.