DNA Ploidy Pattern in Pure Seminomas.

Nuclear extract and image cytometry was used to determine the DNA ploidy pattern of 31 pure seminomas. At least 5-year but usually 10-year follow-up was available to compare the clinical outcome to the DNA ploidy pattern. In 24 cases (77.4%) the DNA indexes (DI) showed tetraploid (1,8 < DI < 2,2) pattern confirming the recent cytogenetic and flow cytometric DNA studies of others. However, in 7 cases (22,6%) the tumors were aneuploid. Out of these aneuploid cases 2 had two subpopulations and 2 had less than 1,8 DI. These latter cases (providing the loss of chromosomal DNA) had elevated AFP levels in serum that raises the question of nonseminomatous transformation without any morphological evidence. Usually, the aneuploid cases had worse prognoses but there was no significant difference. Because of the small number of aneuploid cases wider clinicopathologic studies are required to confirm our results.