[Flow cytometric analysis of DNA content in testicular seminomas--correlation to mitotic count]

The DNA ploidy of testicular seminomas was studied by flow cytometry using paraffin embedded samples. The mitotic count and DNA index (DI) for 27 seminomas were analyzed in 80 samples with a mean of 3.0 samples per case. Six anaplastic seminomas which were with 3 or more mitoses per a high power field were distinguished from 21 typical seminomas. DNA ploidy pattern was aneuploid in all seminomas except one case of anaplastic seminoma, and clonal heterogeneity in DNA content was found in 3 of 20 (15%) cases of which 2 or more samples were analyzed. Although the DI had no significant difference between those two groups of seminomas classified by mitotic count, the DI in anaplastic seminomas was ranged from 1.5 to 2.0 (median DI = 1.70), otherwise the DI in typical seminomas ranged from 1.5 to 3.5 (median DI = 1.89), particularly 9 cases in 21 (43%) typical seminomas distributed in hypertetraploid region. The median DI of stage I seminomas was 1.88 and that of stages II + III seminomas was 1.75, though there was also no significant correlation between DI and clinical stages. In general, it is postulated that the higher DI is paralleled to the more malignant nature of neoplasms, nevertheless this study suggested that the higher DI in seminomas is not always related to high malignant potentiality determined by histological type and clinical stage.