A leprosy patient has diffuse skin thickening, loss of eyebrows, and a Bacterial Index of 5+ on slit-skin smear. Lepromin test is negative. His biopsy shows Virchow cells (foam cells). Classification and the type of immunity is:

• A Tuberculoid leprosy; strong cell-mediated immunity
• B Borderline lepromatous; partial cell-mediated immunity
• C Indeterminate leprosy; normal immunity
• D Lepromatous leprosy; absent cell-mediated immunity ✓

Explanation

Lepromatous leprosy (LL) represents the anergic pole of the leprosy spectrum characterized by absent cell-mediated immunity to M. leprae, as demonstrated by a negative lepromin (Mitsuda) test. High bacillary load (BI 4-6+) results in diffuse skin infiltration, leonine facies, loss of eyebrows (madarosis), and saddle nose. Biopsy shows foam cells (Virchow cells/lepra cells) laden with bacilli but no granuloma formation. Despite poor CMI, humoral immunity is exaggerated, producing auto-antibodies causing false-positive VDRL and rheumatoid factor.

Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.