IMPLICATIONS OF P53 PROTEIN EXPRESSION IN CLEAR-CELL SARCOMA OF THE KIDNEY

Eight histologically-confirmed cases of clear cell sarcoma of the kidn ey (CCSK) were studied for possible mutations in the p53 tumor suppres sor gene by the immunohistochemical demonstration of mutant p53 protei ns using a monoclonal (DO7: Dako) and a polyclonal (AB565: Chemicon) a ntibody to p53 protein. All cases exhibited p53 protein nuclear immuno positivity, although in varying numbers of tumor cells and with differ ent staining intensities. p53 protein (DO7 or AB565) was expressed in < 25% of the tumor cells in four (50%) of the cases, including the one case with a known longterm survival of 13 years from the time of diag nosis. The other tumors showed p53 protein immunopositivity in > 25% o r the tumor cells when stained with either DO7 or AB565 or both. The i ntensity of staining, graded on visual impression into weak, moderate or strong, did not correlate well with the ratio of positive staining tumor cells. While this study is unable to clarify the relative preval ence and importance of p53 mutational events in the pathogenesis of th is aggressive renal tumor of childhood, it is reasonably suggestive th at alterations in the p53 tumor suppressor gene do occur in CCSK.