TP53 and ossifying fibroma: Apart from necrosis, various other potential prognostic markers that have been identified include tumor cell ploidy, expression of HER2/CerbB2, gains and loss of specific chromosomes, loss of RB and p53 gene heterozygosity, and overexpression of P-glycoprotein.3MDM2 overexpression and amplification are found to be molecular makers for low-grade and dedifferentiated mandibular OS and are not seen in lesions such as fibrous dysplasia and ossifying fibroma.