Oral lichen planus is best described as?

• A. Autoimmune blistering disease with mucosal involvement
• B. Bacterial infection of mucosa
• C. Fungal overgrowth with white plaques
• D. T-cell mediated inflammatory reaction; increased incidence with HCV infection

Answer: (D)

Oral lichen planus is a chronic mucosal condition driven by a T-cell–mediated immune response against basal keratinocytes in the oral epithelium. This immune attack creates an interface dermatitis with a band of lymphocytes hugging the epithelial basement membrane and basal cell degeneration, often presenting clinically as reticular white intersecting lines (Wickham’s striae) or as erosive lesions. The association with hepatitis C infection explains why there is an increased incidence in people with that viral infection. It is not an autoimmune blistering disease, which would involve vesicles or bullae from antibodies targeting components of the skin or mucosa, nor is it a bacterial mucosal infection or a fungal overgrowth like candidiasis, which produces easily scrape-off white plaques or pseudohyphae on microscopy. In short, the hallmark is a T-cell–driven inflammatory reaction in the mucosa, with a known link to hepatitis C.