[Cell cycle: regulation and abnormalities in epidermal tumors].

The size of a tissue such as the epidermis, and its potential growth, results from the balance between cell production and loss. The mechanisms controlling these two parameters are still poorly understood. Major advances have however been recently achieved in our knowledge of cell cycle regulation and programmed cell death. Dysregulation could explain the development of neoplastic tumors. Basal cell carcinoma basically results from a fall in programmed cell death. Spindle cell carcinoma results from an increased cell production. Both mechanisms are involved in melanoma. One must however keep in mind the fact that we are dealing with hypotheses which remain to be verified.