Frictional (Sock) Alopecia of the Legs: Trichoscopy as an Aid.

Alopecia of the lower limbs is a rarely reported entity. Friction due to footwear, socks, and tight clothing is one of the causes of lower limb alopecia. The typical site of involvement and improvement after removal of triggering factor are an important clue to the diagnosis. Alopecia areata remains a close differential, and dermoscopy/trichoscopy can serve as an adjunctive aid in the diagnosis.