Serum usually follows inflammatory cells into the epidermis through simple osmotic forces. Exocytosis is the presence of inflammatory cells in the intercellular space in the epidermis. As in other organs, the presence of inflammatory cells in the epidermis usually indicates an immunological response of the body's immune system to a perceived or real antigenic stimulation. The Langerhans cell is a bone marrow derived cell that nn grates to the epidermis during fetal development and acts as the antigen presenting cell in the epidermis. 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.