A 28-year-old woman from Tamil Nadu with tuberculoid leprosy (TT) on MDT for 6 weeks presents with sudden onset inflammation of her existing skin lesions and peripheral nerve thickening. She develops acute neuritis of the ulnar nerve with pain and weakness. Histopathology of the lesion shows epithelioid granulomas with activated macrophages. Her bacillary index has decreased significantly. What is the most appropriate immediate management?

Explanation

## Diagnosis and Management: Type 1 Lepra Reaction (Reversal Reaction) ### Clinical Presentation The patient presents with: - Inflammation of **existing lesions** (not new nodules) - **Acute neuritis** with nerve thickening and functional loss - Occurs during MDT (6 weeks) - **Decreased bacillary index** (immune response improving) - **Epithelioid granulomas** on histology (cell-mediated immunity) ### Pathophysiology **Key Point:** Type 1 lepra reaction (reversal reaction) is a **cell-mediated (Type IV hypersensitivity)** reaction that reflects upgrading or downgrading of immunity in unstable borderline forms of leprosy. **High-Yield:** Type 1 reactions: - Occur in **BT, BB, and BL** (unstable forms) - Are **NOT** seen in pure TT or LL - Represent a shift in the Ridley-Jopling spectrum - Can cause **irreversible nerve damage** if untreated - Require **urgent steroid therapy** to prevent disability ### Why This Is Type 1 Reaction | Feature | Finding in This Case | |---------|----------------------| | **Lesion involvement** | Inflammation of existing lesions ✓ | | **Nerve involvement** | Acute neuritis with functional loss ✓ | | **Histology** | Epithelioid granulomas, activated macrophages ✓ | | **Bacillary index** | Decreased (immune response active) ✓ | | **Leprosy type** | TT (borderline form) ✓ | | **Timing** | During treatment ✓ | ### Management Algorithm ```mermaid flowchart TD A[Type 1 Lepra Reaction Diagnosed]:::outcome --> B{Nerve Involvement?}:::decision B -->|No nerve damage| C[Prednisolone 0.5 mg/kg/day]:::action B -->|Neuritis present| D[Prednisolone 1 mg/kg/day]:::action D --> E[Continue MDT without interruption]:::action C --> E E --> F[Assess response at 2-4 weeks]:::action F --> G{Improvement?}:::decision G -->|Yes| H[Taper steroids over 3-6 months]:::action G -->|No| I[Increase prednisolone to 1.5 mg/kg/day]:::action H --> J[Complete MDT course]:::action I --> J ``` ### Why Prednisolone? **Clinical Pearl:** Steroids suppress the cell-mediated immune response that is causing the inflammation, thereby: 1. Reducing inflammation of existing lesions 2. **Preventing irreversible nerve damage** (critical in acute neuritis) 3. Allowing continued MDT to eliminate bacilli 4. Preventing disability and deformity **High-Yield:** The key principle is **"Continue MDT + Add Steroids"** — do NOT stop MDT, as this allows bacterial proliferation. ### Dosing and Duration - **Mild reaction (no neuritis):** Prednisolone 0.5 mg/kg/day - **Moderate/Severe (with neuritis):** Prednisolone 1–2 mg/kg/day - **Duration:** Taper over 3–6 months based on response - **Monitoring:** Assess nerve function at 2–4 weeks; if no improvement, increase dose **Mnemonic:** **Type 1 = Taper with Steroids + Treat with MDT** ### Why NOT Thalidomide? Thalidomide is the drug of choice for **Type 2 reactions (ENL)**, not Type 1. Type 1 is cell-mediated and responds to steroids. Thalidomide is reserved for immune complex reactions.