A 42-year-old woman from Tamil Nadu presents with a single well-demarcated hypopigmented macule on her left forearm with complete loss of sensation. Examination reveals thickening of the left ulnar nerve only. Slit-skin smear from the lesion is negative for acid-fast bacilli. Lepromin test is strongly positive. Skin biopsy shows epithelioid granulomas with Langhans giant cells and minimal bacilli. What is the most appropriate initial antileprosy regimen for this patient?

Explanation

## Classification and Treatment Rationale **Key Point:** This patient has **paucibacillary tuberculoid leprosy** (single lesion, negative slit-skin smear, strongly positive lepromin test, epithelioid granulomas). The WHO-MDT regimen for paucibacillary leprosy is the standard of care. ### Diagnosis: Tuberculoid Leprosy (TT) | Finding | Significance | |---|---| | Single well-demarcated lesion | Typical of TT (1–5 lesions) | | Negative slit-skin smear | Paucibacillary disease | | Strongly positive lepromin test | Robust Th1 immunity | | Epithelioid granulomas with LGCs | Histologic hallmark of TT | | Asymmetric nerve involvement (left ulnar only) | Early, localized nerve damage | ### WHO-MDT Regimens for Leprosy | Classification | WHO Regimen | Duration | Drugs | |---|---|---|---| | **Paucibacillary (PB)** | **Rifampicin + Dapsone** | **6 months** | **Monthly supervised doses + daily self-administered doses** | | Multibacillary (MB) | Rifampicin + Dapsone + Clofazimine | 12 months | Monthly supervised + daily self-administered | | Single lesion | Rifampicin + Ofloxacin + Minocycline (ROM) | 4 weeks | Single dose (for single lesion only) | **High-Yield:** The **6-month paucibacillary regimen** (Rifampicin + Dapsone) is the standard for tuberculoid and borderline tuberculoid leprosy. This patient has clear TT features, so the 6-month regimen is appropriate. **Clinical Pearl:** Rifampicin is the backbone of all leprosy regimens — it is bactericidal and renders patients non-infectious within 2 weeks. Dapsone is bacteriostatic and prevents resistance. Clofazimine is reserved for multibacillary disease due to its slow action and cosmetic side effects (blue-black pigmentation). **Mnemonic — PB vs MB regimens:** - **PB (Paucibacillary) = 2 drugs, 6 months** (Rif + Dap) - **MB (Multibacillary) = 3 drugs, 12 months** (Rif + Dap + Clof) - **Single lesion = ROM, 4 weeks** (Rif + Oflox + Minocycline) ### Why Not Other Options? 1. **12-month three-drug regimen:** Reserved for multibacillary leprosy (high bacillary load). This patient is paucibacillary. 2. **Monotherapy:** Monotherapy with rifampicin alone risks resistance and is never used in leprosy. 3. **ROM (Rifampicin + Ofloxacin + Minocycline):** This 4-week regimen is used ONLY for single-lesion leprosy. Although this patient has one lesion, ROM is typically reserved for very early, single-lesion disease without nerve involvement. With established nerve thickening, the standard 6-month PB regimen is more appropriate for complete resolution.