In the last three decades, the premalignant cutaneous lesions have represented a milestone for the clinicians and the anatomopathologists given the increased risk of malignant transformation not only in the old but also in the young population. Recent research indicates the fact that, though multiple progresses were recorded in the diagnosis and treatment of the cutaneous squamocellular carcinomas, developed in more than 85% of the cases in premalignant lesions, however the prognosis and survival up to five years did not register significant improvements. For the achievement of the diagnosis with certainty, the histopathological examination, considered until recently the "golden standard", principally based on the TNM criterion, has an increased percentage of subjectivity and it is relatively unsure, being known the fact that two apparently identical tumors answer differently to the same therapy. The variability of the morphological aspects from simple dysplasia to in situ carcinomas and the cancers themselves impose the identification of some cellular and molecular markers typical to the premalignant and malignant cutaneous lesions. In this respect, the knowledge and characterization of the molecular mosaic allow the establishment of some clear criterion for an early diagnosis, corresponding monitoring and adequate treatment.