A 42-year-old woman from Odisha presents with a single well-demarcated hypopigmented macule over her left forearm with loss of sensation. Slit-skin smear is negative for acid-fast bacilli. Lepromin test is strongly positive. Nerve palpation shows mild thickening of the radial nerve. What is the appropriate MDT regimen and duration for this patient?

## Classification and MDT Selection This patient has **tuberculoid leprosy (TT)** or **paucibacillary (PB) disease** based on: - Single skin lesion (≤5 lesions = PB) - Negative slit-skin smear (low/absent bacillary load) - Positive lepromin test (strong cell-mediated immunity) - Well-demarcated lesion with clear sensory loss ### WHO MDT Regimen for Paucibacillary Leprosy **Key Point:** Paucibacillary leprosy requires the **2-drug regimen** for **6 months**. | Component | Drug | Dose | Frequency | |-----------|------|------|----------| | **Backbone** | Rifampicin | 600 mg | Monthly supervised | | **Backbone** | Dapsone | 100 mg | Daily self-administered | | **Duration** | — | — | **6 months** | **High-Yield:** The PB regimen is: - **Shorter** (6 months vs. 12 months for MB) - **Simpler** (2 drugs vs. 3 drugs) - **Equally effective** because bacillary load is low - **Lower relapse rate** (<1%) due to robust cell immunity ### Distinction: PB vs. MB Classification | Feature | Paucibacillary (PB) | Multibacillary (MB) | |---------|-------------------|-------------------| | **Lesion count** | ≤5 lesions | >5 lesions | | **Slit-skin smear** | Negative (0 AFB) | Positive (1+ to 6+ AFB) | | **Lepromin test** | Positive | Negative | | **Bacillary load** | Low | High | | **MDT regimen** | Rifampicin + Dapsone | Rifampicin + Dapsone + Clofazimine | | **Duration** | **6 months** | **12 months** | | **Relapse rate** | <1% | 5–10% if undertreated | **Clinical Pearl:** A positive lepromin test in a patient with few lesions and negative smear is virtually diagnostic of tuberculoid leprosy and indicates excellent prognosis. These patients respond rapidly to MDT and rarely relapse. **Mnemonic:** **PB = 2 drugs × 6 months** (Rifampicin + Dapsone for half a year); **MB = 3 drugs × 12 months** (add Clofazimine for full year).