Which statement correctly distinguishes tuberculoid leprosy (TT) from indeterminate leprosy histopathologically?

• A TT shows perineural granulomas and destruction of nerve fascicles; indeterminate shows only peri-appendageal and perineural lymphocytic infiltrate ✓
• B TT shows foam cells (Virchow cells) in the dermis; indeterminate shows epithelioid granulomas
• C TT shows subepidermal clear zone; indeterminate shows epidermotropism
• D TT shows non-caseating granulomas with no clear zone; indeterminate shows perineural granulomas only

Explanation

Tuberculoid leprosy (TT) histopathology shows well-formed epithelioid granulomas that invade up to the basal layer (no subepidermal clear/grenz zone), with perineural granulomas that destroy nerve architecture — a key distinguishing feature. Indeterminate leprosy (I) shows only a perivascular, peri-appendageal, and perineural non-specific lymphohistiocytic infiltrate without well-formed granulomas. AFB are usually absent in both TT and I, but TT shows well-formed tuberculoid granulomas whereas I has no granulomas. Foam cells (Virchow cells) laden with AFB are characteristic of lepromatous leprosy.

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.