Comparison of p53 expression in dermatofibrosarcoma protuberans and dermatofibroma: lack of correlation with proliferation rate.

p53 protein plays an important role in control of cell proliferation by suppressing proliferation of cells with DNA damage. Mutations of the p53 gene increase the stability of the encoded nonfunctional protein which accumulates in the nuclei, allowing it to be detectable by immunohistochemistry. Mutant p53 protein has been observed in preneoplastic and neoplastic conditions supporting its role in the development of some human cancers. In this immunohistochemical study, we examined p53 expression in 12 Dermatofibrosarcoma Protuberans (DFSP) and 10 Dermatofibromas (DF). Results were compared with the cellular proliferation rate by using the monoclonal antibody Mib-1 which detects Ki-67 antigen expression. Nuclear accumulation of the p53 protein was observed in 11 DFSP. All DF were negative for p53. No statistical correlation could be established between p53 and Mib-1 staining in our cases. We conclude that mutations of the p53 gene may be involved in the molecular pathogenesis of DFSP but not of DF. Mib-1 index can not be successfully used to distinguish DFSP from DF.