Variable ploidy of ovarian clear cell carcinomas. Implications for adequacy of tissue sampling.

Ten cases of clear cell (mesonephroid) adenocarcinoma of the ovary were examined for (1) variations of morphology within each tumor and its metastases, (2) ploidy of each morphologic region and (3) clinical behavior. Correlations were sought among these factors. Analysis of the ploidy in up to six morphologic regions per tumor showed variations in the ploidy in seven of the ten cases, with all seven having both diploid and nondiploid regions. The presence or absence of abnormal ploidy was not predictable based on the histomorphologic appearance of a given section. These results suggest that (1) the evaluation of a single random tissue sample may not discover aneuploidy that is present and (2) future ploidy studies on malignant tumors may require extensive tumor sampling in order to definitively exclude the presence of aneuploid populations.