A 42-year-old woman from Tamil Nadu presents with 8 hypopigmented macules on her trunk and limbs, with moderate sensory loss. Slit-skin smear shows 4+ acid-fast bacilli. Bilateral ulnar and lateral popliteal nerves are palpably thickened and tender. What is the most appropriate next step in management?

Explanation

## Borderline Leprosy: Classification & Immediate Management **Key Point:** This patient has multiple lesions (8), moderate bacillary load (4+), and **bilateral nerve thickening** — the hallmark of borderline leprosy (BT/BL/BB). The next step is to start 12-month MDT and assess for lepra reactions at baseline. ### Clinical Features Indicating Borderline Leprosy | Feature | This Patient | Classification | |---------|--------------|----------------| | Number of lesions | 8 | Borderline (5–many) | | Bacillary load | 4+ | Borderline/Lepromatous | | Nerve involvement | Bilateral, thickened, tender | **Borderline (symmetric, early)** | | Sensory loss | Moderate | Borderline | **High-Yield:** The presence of **bilateral, symmetric nerve thickening** is the key discriminator: - **Tuberculoid (TT):** Early, asymmetric nerve involvement (1–2 nerves) - **Borderline (BT/BL/BB):** Symmetric, multiple nerve involvement (bilateral) - **Lepromatous (LL):** Late, symmetric nerve involvement with glove-and-stocking distribution ### Why Start 12-Month MDT Immediately? 1. **Borderline leprosy is unstable** — it can shift toward tuberculoid (reversal reaction) or lepromatous (erythema nodosum leprosum) poles. 2. **Baseline assessment for lepra reactions is mandatory** — borderline patients are at highest risk for Type 1 (reversal) and Type 2 (ENL) reactions. 3. **Early treatment prevents nerve damage** — symmetric nerve involvement means multiple nerves are at risk; delay increases disability. 4. **WHO MDT for borderline leprosy is 12 months** — longer than tuberculoid (6 months) due to higher bacillary load and instability. **Mnemonic: Bilateral Nerves + Borderline bacilli = 12-month MDT + assess for reactions** ### Baseline Lepra Reaction Assessment **Clinical Pearl:** Before starting MDT in borderline leprosy, document: - Baseline nerve function (motor, sensory) - Presence of any erythematous nodules or plaques (ENL risk) - Baseline eye examination (lagophthalmos, iritis) - Baseline systemic symptoms (fever, arthralgia) This baseline is critical because lepra reactions can occur during or after treatment and may mimic treatment failure if not recognized. ### Why Not the Other Options? See distractor reasoning below.