## Lepra Reaction Type 2 (Erythema Nodosum Leprosum) ### Clinical Presentation This patient has **Erythema Nodosum Leprosum (ENL)**, a Type III hypersensitivity reaction (immune complex-mediated) occurring in lepromatous and borderline lepromatous leprosy. **Key Point:** ENL typically occurs during or after MDT, characterized by tender nodules, fever, arthralgia, and histologically shows neutrophilic infiltration with vasculitis. ### Drug of Choice: Prednisolone | Feature | Details | |---------|----------| | **First-line agent** | Prednisolone (corticosteroid) | | **Dose** | 0.5–1 mg/kg/day, tapered over weeks | | **Mechanism** | Suppresses immune complex deposition and inflammation | | **Onset** | Rapid response (days to weeks) | | **Duration** | Continue until lesions resolve, then taper | ### When to Use Thalidomide **High-Yield:** Thalidomide is reserved for: - Prednisolone-dependent or steroid-resistant ENL - Severe, recurrent ENL - Dose: 100–300 mg/day - Requires strict contraception (teratogenic) ### Management Algorithm ```mermaid flowchart TD A[ENL diagnosed]:::outcome --> B{Severity?}:::decision B -->|Mild-moderate| C[Prednisolone 0.5-1 mg/kg/day]:::action B -->|Severe| D[Prednisolone + NSAIDs]:::action C --> E{Response in 2-4 weeks?}:::decision E -->|Yes| F[Taper prednisolone]:::action E -->|No| G[Add thalidomide 100-300 mg/day]:::action D --> H[Assess response at 4 weeks]:::decision H -->|Inadequate| G G --> I[Continue until resolution]:::action ``` **Clinical Pearl:** Prednisolone works by suppressing the immune response and reducing TNF-α production, which drives ENL pathogenesis. **Warning:** Do not confuse ENL (Type III) with Type 1 lepra reaction (reversal reaction), which is treated with prednisolone but is a Type IV hypersensitivity.
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