Bowen's disease. Light micrograph of a section through a skin lesion on the vulva caused by Bowen's disease. Bowen's disease is a form of epidermal dysplasia, affecting the cells of the epidermis, but not the dermis. The surface cornified layer of the skin (pink, bottom right) shows parakeratosis (abnormality in the process of keratinisation). The normal organisation and stratification of cells in the epidermis (purple) is lost. This manifests as dull red, slightly scaly plaques on the skin of the trunk, legs and genitals. Bowen's disease is an early phase of skin cancer, but can be treated by removal with liquid nitrogen (cryotherapy).