A patient with borderline tuberculoid (BT) leprosy on MDT develops sudden worsening of existing skin lesions with new tenderness and erythema of the lesions, painful peripheral nerve thickening, and neuritis. There is no fever and no new skin lesions. This is consistent with:

• A Erythema nodosum leprosum (ENL — Type 2 reaction)
• B Lucio phenomenon
• C Downgrading reaction
• D Reversal reaction (Type 1 reaction) ✓

Explanation

A Type 1 (reversal) reaction occurs in borderline leprosy (BT, BB, BL) due to sudden increase in cell-mediated immunity toward existing lesions. It presents as erythema and oedema of pre-existing skin lesions and acute neuritis. No new lesions or systemic features (fever, tender nodules) occur, distinguishing it from ENL (Type 2), which involves new tender erythematous nodules, fever, and systemic features (iritis, orchitis, glomerulonephritis) in lepromatous or borderline lepromatous leprosy. Reversal reaction requires urgent high-dose prednisolone to prevent irreversible nerve damage.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.