A 72-year-old woman from Delhi presents with a 2-month history of recurrent tense bullae on her lower legs and abdomen. She reports mild pruritus. Skin examination reveals several intact bullae with surrounding urticarial plaques. Direct immunofluorescence shows linear IgG and C3 deposition along the basement membrane zone. Indirect immunofluorescence (serum) is positive for circulating IgG antibodies. The patient is otherwise healthy with no significant past medical history. What is the most appropriate initial pharmacological management?

Explanation

## Management of Bullous Pemphigoid: First-Line Therapy ### Treatment Algorithm ```mermaid flowchart TD A[Bullous Pemphigoid Diagnosis Confirmed]:::outcome --> B{Extent of Disease?}:::decision B -->|Localized/Mild| C[Topical Corticosteroids ± Antihistamines]:::action B -->|Generalized/Moderate-Severe| D[Systemic Corticosteroids]:::action D --> E[Prednisolone 0.5-1 mg/kg/day]:::action E --> F[Taper over 3-6 months]:::action F --> G{Response Adequate?}:::decision G -->|Yes| H[Continue maintenance]:::action G -->|No/Steroid-Dependent| I[Add Steroid-Sparing Agent]:::action I --> J[Azathioprine or Mycophenolate]:::action ``` ### Why Systemic Corticosteroids Are First-Line **Key Point:** Systemic corticosteroids are the **gold standard first-line therapy** for generalized bullous pemphigoid. Prednisolone at **0.5–1 mg/kg/day** achieves remission in >90% of patients. ### Rationale for This Patient - **Generalized distribution** (lower legs AND abdomen) — not localized - **Multiple bullae over 2 months** — indicates progressive, moderate disease - **Positive serology** (circulating IgG) — suggests active, systemic autoimmunity - **No contraindications mentioned** — age alone is not a contraindication in elderly patients with BP ### Mechanism of Action Corticosteroids suppress: 1. T-cell activation and IL-2 production 2. Eosinophil recruitment and degranulation 3. Antibody production by B cells 4. Complement activation at the basement membrane ### Treatment Escalation Strategy | Stage | Therapy | Indication | |-------|---------|------------| | **Mild/Localized** | Potent topical steroids ± antihistamines | <10% BSA involvement | | **Moderate/Generalized** | Systemic prednisolone 0.5–1 mg/kg/day | >10% BSA; multiple bullae | | **Steroid-dependent** | Add azathioprine (1–2 mg/kg/day) or mycophenolate | Cannot taper below 10–15 mg/day | | **Severe/Refractory** | Rituximab, IV immunoglobulin, or plasmapheresis | Failure of conventional therapy | **High-Yield:** The goal is to achieve **complete remission within 4–8 weeks**, then gradually taper over 3–6 months to minimize long-term steroid toxicity. ### Clinical Pearl Unlike pemphigus vulgaris (which often requires higher doses and longer treatment), bullous pemphigoid responds more readily to lower-dose corticosteroids, and many patients achieve long-term remission or even cure after tapering. **Mnemonic: STEROID SPARING** — When to add steroid-sparing agents: - **S**teroid-dependent (cannot taper <10–15 mg/day) - **T**oxicity concerns (diabetes, osteoporosis, infections) - **E**arly introduction (some centers add at baseline in elderly) - **R**efractoriness to monotherapy - **O**ther comorbidities precluding high-dose steroids - **I**mmune suppression desired - **D**uration >3 months anticipated [cite:Robbins 10e Ch 25; Harrison 21e Ch 324]