RB1 and chondrogenic neoplasm: Several signaling pathways have been shown to be affected in central cartilaginous neoplasms: RB1 and TP53, cytogenetic alterations and mutations in the IDH1 and IDH2 genes, as well as the analysis of DNA ploidy by cytofluorometry, which has improved the knowledge of the origin and real nature of this type of lesion.