Dysplasia is used to describe cells that show aberrant growth and differentiation. Dysplastic cells lie in a continuum between benign and fully malignant. Dysplasia represents a stop action photograph of one of the earliest and still reversible steps in the multistep process of malignancy. It may affect any epithelial cell in the body. In the epidermis, dysplasia arises in the basal keratinocytes and is reflected by disorganization and enlargement of the cells.
Erosion is incomplete loss of the epidermis.
This is in contrast with ulceration which is complete loss of the epidermis and frequently a portion of the superficial dermis.