Eight histologically-confirmed cases of
clear cell sarcoma of the kidney (CCSK) were studied for possible mutations in the p53 tumor suppressor gene by the immunohistochemical demonstration of mutant p53
proteins using a monoclonal (DO7: Dako) and a polyclonal (AB565: Chemicon) antibody to p53
protein. All cases exhibited p53
protein nuclear immunopositivity, although in varying numbers of
tumor cells and with different 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 long term survival of 13 years from the time of diagnosis. The other
tumors showed p53
protein immunopositivity in > 25% of the
tumor cells when stained with either DO7 or AB565 or both. The intensity 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 prevalence and importance of p53 mutational events in the pathogenesis of this aggressive renal
tumor of childhood, it is reasonably suggestive that alterations in the p53 tumor suppressor gene do occur in CCSK.