A 28-year-old woman from Odisha presents with a single well-demarcated hypopigmented macule on her left forearm with loss of sensation. Slit-skin smear is negative for acid-fast bacilli. Lepromin test is strongly positive. She has no systemic symptoms and no nerve thickening. What is the most appropriate MDT regimen for this patient?

## Classification and MDT Selection **Key Point:** The patient has paucibacillary leprosy (PB) based on: - Single lesion (≤5) - Negative slit-skin smear (AFB negative) - Positive lepromin test (indicates intact cell-mediated immunity) - Clinical features of tuberculoid leprosy (TT) ### WHO MDT Classification and Regimens ```mermaid flowchart TD A[Suspected Leprosy]:::outcome --> B{Number of lesions?}:::decision B -->|≤5 lesions| C{Slit-skin smear?}:::decision B -->|>5 lesions| D[Multibacillary]:::outcome C -->|Negative| E[Paucibacillary]:::outcome C -->|Positive| F[Multibacillary]:::outcome D --> G[Rifampicin + Dapsone + Clofazimine<br/>12 months]:::action E --> H[Rifampicin + Dapsone<br/>6 months]:::action F --> G ``` ### PB vs MB Comparison | Feature | Paucibacillary (PB) | Multibacillary (MB) | |---|---|---| | **Lesions** | ≤5 | >5 | | **Slit-skin smear** | Negative | Positive (BI ≥1) | | **Lepromin test** | Positive | Negative | | **Bacillary load** | Low | High | | **MDT Drugs** | Rifampicin + Dapsone | Rifampicin + Dapsone + Clofazimine | | **Duration** | 6 months | 12 months | | **Relapse rate** | <1% | 1–5% | ### PB MDT Regimen Details **Monthly supervised doses:** 1. Rifampicin 600 mg 2. Dapsone 100 mg **Daily unsupervised doses:** - Dapsone 100 mg **High-Yield:** Paucibacillary leprosy has excellent prognosis with 2-drug MDT because: - Low bacillary burden - Strong host immunity (positive lepromin) - Low relapse risk (<1%) - Clofazimine is unnecessary **Clinical Pearl:** A positive lepromin test indicates tuberculoid leprosy (TT), which is at the tuberculoid pole of the Ridley-Jopling classification. These patients have strong cell-mediated immunity and excellent treatment outcomes. **Warning:** Do NOT add clofazimine to PB regimens—it is not indicated and increases cost and side effects without benefit. The 6-month 2-drug regimen is sufficient and WHO-recommended for all PB cases. **Mnemonic:** **PB = 2 drugs, 6 months, Positive lepromin** (Rifampicin + Dapsone); **MB = 3 drugs, 12 months, Negative lepromin** [cite:Park 26e Ch 7]