In borderline leprosy with a Type 1 reversal reaction, palpably thickened tender nerves place the limb at risk of permanent paralysis. Which set of peripheral nerves is most characteristically enlarged and palpable in leprosy?

• A Ulnar, lateral popliteal, and posterior auricular nerves ✓
• B Median, femoral, and obturator nerves
• C Radial, axillary, and sciatic nerves
• D Phrenic, suprascapular, and tibial nerves

Explanation

M. leprae preferentially infects cooler superficial nerves. The classic palpably thickened nerves are the ulnar at the elbow, the lateral popliteal (common peroneal) around the fibular neck, the great auricular, and the posterior auricular nerves. Ulnar involvement produces claw hand, while lateral popliteal involvement produces foot drop. Deep-seated nerves such as the sciatic, femoral, and obturator lie too warm and deep to be affected clinically, making those distractors anatomically implausible.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.