MDM2 AMPLIFICATION, P53 MUTATION, AND ACCUMULATION OF THE P53 GENE-PRODUCT IN MALIGNANT FIBROUS HISTIOCYTOMA

Fifty-two cases of malignant fibrous histiocytoma (MFH) were evaluated for amplification of the MDM2 gene, mutation of the P53 gene, accumul ation of the P53 gene product, and their relation to disease-free and overall survival. All tests were carried out on formalin-fixed, paraff in-embedded tissue samples. Amplification of the MDM2 gene was detecte d in 15 of 52 cases (29%). Six of 52 cases (12%) demonstrated abnormal ities of the P53 gene. Sequence analysis detected point mutations in f our cases and a 1-base pair deletion in one case, whereas differential polymerase chain reaction (dPCR) indicated that the P53 gene had been entirely deleted in one case. Eight of 52 cases (15%) demonstrated st aining for the P53 protein in >10% of tumor cells. The presence of MDM 2 amplification did not have a significant effect on either disease-fr ee or overall survival. Patients with accumulation of the P53 gene pro duct did not differ in disease-free or overall survival from patients without P53 accumulation. Survival also was not significantly differen t in patients with genetic aberration in P53. However, when the patien ts were stratified by histologic grade, the results indicated that pat ients with alterations in the P53 gene may have shorter overall surviv al.