Cornoid lamellation is a specific disorder of epidermal maturation manifested by a vertical "column" of parakeratosis and is the hallmark of porokeratosis. The cornoid lamella is characterized by a ridgelike parakeratosis. We present 11 patients with solitary lesions of a distinct pattern of cornoid lamellation. The mean age at presentation clinically was 57 years; there were 9 men and 2 women....