A 42-year-old woman with borderline tuberculoid leprosy (BT) of 3 months' duration presents with sudden onset of pain and swelling in existing skin lesions and peripheral nerves. On examination, the lesions have become more erythematous and edematous, and there is acute tenderness along the ulnar and posterior tibial nerves. Slit-skin smear remains negative. Histopathology shows increased epithelioid cell granulomas with caseation. She has been on MDT for 4 weeks. What is the most appropriate management?

Explanation

## Diagnosis: Type 1 Lepra Reaction (Reversal Reaction) ### Clinical Features Matching Type 1 RR - **Patient profile:** Borderline form (BT) — Type 1 RR occurs in borderline patients (BT, BL, BB) - **Timing:** 4 weeks into MDT — classic timing for reversal reaction (can occur during or shortly after starting treatment) - **Skin findings:** Acute inflammation of existing lesions (erythema, edema, induration) - **Nerve involvement:** Acute neuritis with tenderness along major nerves (ulnar, posterior tibial) — hallmark of Type 1 RR - **Slit-skin smear:** Negative (consistent with BT, low bacillary load) - **Histology:** Increased epithelioid granulomas with caseation — reflects enhanced cell-mediated immunity ### Pathophysiology **Key Point:** Type 1 lepra reaction is a **Type IV hypersensitivity reaction (cell-mediated immunity)** representing a shift toward the tuberculoid pole. It is triggered by immune reconstitution (especially in BT/BL patients) during or shortly after MDT initiation. ### Type 1 vs Type 2 Comparison | Feature | Type 1 (RR) | Type 2 (ENL) | |---------|-------------|-------------| | **Bacillary load** | Low-to-moderate (BT-BL) | High (LL-BL) | | **Timing** | During/shortly after MDT start | 6 months–2 years post-MDT | | **Mechanism** | Type IV (CMI) | Type III (IC) | | **Lesion changes** | Existing lesions inflame | New tender nodules | | **Nerve involvement** | Acute neuritis (tender) | Rare | | **Systemic signs** | Minimal | Fever, constitutional | | **Histology** | Enhanced epithelioid granulomas | Neutrophilic + IC | | **SSS** | Negative/low | Positive (high load) | **High-Yield:** **Acute neuritis in a borderline patient on early MDT = Type 1 RR until proven otherwise.** Nerve tenderness is the cardinal sign. ### Management of Type 1 RR 1. **Continue MDT** — do NOT stop or modify 2. **Corticosteroids:** Prednisolone 0.5–1 mg/kg/day, taper over 12–16 weeks 3. **NSAIDs** for symptomatic relief 4. **Physiotherapy** to prevent nerve damage and contractures 5. **Monitor for neuritis progression** — may require surgical decompression if severe **Clinical Pearl:** Untreated Type 1 RR can lead to permanent nerve damage and disability. Early recognition and corticosteroid therapy are crucial to prevent irreversible motor/sensory loss. **Mnemonic:** **BURN** for Type 1 RR in **B**orderline patients: - **B** — Borderline forms (BT, BL, BB) - **U** — Upgrade in immunity (shift toward tuberculoid) - **R** — Reaction during/early in MDT - **N** — Neuritis (acute nerve inflammation) [cite:Park 26e Ch 26]