Lichen planopilaris (LPP) is a form of primary scarring alopecia. Which histopathological feature at the isthmus-infundibulum level distinguishes LPP from discoid lupus of the scalp?

• A LPP shows basement membrane thickening with IgG/IgM deposits; DLE shows perifollicular lichenoid infiltrate
• B LPP shows lymphocytic folliculocentric infiltrate at the isthmus with perifollicular fibrosis; DLE shows interface change at the epidermis and follicular plugging ✓
• C LPP shows neutrophilic infiltrate with follicular destruction; DLE shows lymphocyte-only infiltrate
• D LPP shows sebaceous gland hyperplasia; DLE shows complete absence of sebaceous glands

Explanation

Lichen planopilaris (LPP) histopathology shows a perifollicular lymphocytic lichenoid infiltrate concentrated at the isthmus and lower infundibulum, with perifollicular lamellar fibrosis and destruction of the hair bulge region where follicular stem cells reside — leading to irreversible scarring alopecia. Discoid lupus erythematosus (DLE) of the scalp shows interface dermatitis at the epidermal and follicular surface, follicular plugging, basement membrane thickening, and mucin deposition in the dermis; DIF shows granular IgG/IgM/C3 at the DEJ (lupus band). LPP does not show basement membrane thickening or lupus band on DIF, but may show colloid bodies.

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

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Written and medically reviewed by the StethoPrep medical team.