This person has a wart (verruca) that has built up a cutaneous horn which is made up of hard keratin. This does not slough-off like normal skin cells.
Review Date 6/7/2023
Updated by: Elika Hoss, MD, Assistant Professor of Dermatology, Mayo Clinic, Scottsdale, AZ. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.