Which description correctly differentiates lichen planus from lichen simplex, focusing on planus?

• A. Lichen planus shows Wickham's striae on polygonal flat-topped papules
• B. Lichen simplex shows Wickham's striae
• C. Lichen planus is contagious
• D. Lichen planus presents with diffuse vesicular lesions

Answer: (D)

Wickham's striae on polygonal flat-topped papules are the hallmark of lichen planus. Those fine white lines visible on the surface of the lesions help distinguish planus from lichen simplex chronicus, which presents as thickened, leathery plaques from chronic scratching and lacks these characteristic Wickham’s striae. Planus is not contagious, and diffuse vesicular lesions are not typical of classic lichen planus, reinforcing that the presence of Wickham's striae on the classic papules is the best description for differentiating planus from its counterpart.