A 35-year-old male farmer from Rajasthan presents with a 3-year history of anaesthetic hypopigmented patches on the trunk, thickening of the ulnar and great auricular nerves, and clawing of the 4th and 5th fingers of the left hand. Slit-skin smear (SSS) from the active edge of the lesion shows no AFB (BI = 0). What is the Ridley-Jopling classification and WHO MB/PB regimen applicable here?
- A Lepromatous leprosy (LL); WHO MB regimen for 12 months
- B Borderline tuberculoid (BT) leprosy with nerve involvement; WHO PB regimen (Rifampicin + Dapsone) for 6 months ✓
- C Tuberculoid (TT) leprosy; WHO PB regimen for 6 months
- D Borderline lepromatous (BL) leprosy; WHO MB regimen for 12 months
Explanation
The combination of 2–5 asymmetric hypopigmented anaesthetic patches, thickened peripheral nerves, and a negative SSS (BI = 0) with clawing of the ulnar nerve territory is classic for borderline tuberculoid (BT) leprosy. BT leprosy has 2–5 skin lesions (TT has ≤5 with one nerve trunk; BL/LL have >5). A negative SSS (paucibacillary spectrum) in the context of multiple lesions and one nerve trunk involvement puts this firmly in the PB group (WHO defines PB as ≤5 patches). WHO PB regimen: Rifampicin 600 mg monthly (supervised) + Dapsone 100 mg daily for 6 months.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.