DNA-PLOIDY OF HYDATIDIFORM MOLES AND NONMOLAR CONCEPTUSES - A STUDY USING FLOW AND TISSUE SECTION IMAGE CYTOMETRY

This study was performed to investigate the role of DNA cytometry in t he evaluation of molar and nonmolar pregnancies. DNA ploidy analysis w as performed on paraffin-embedded tissue from 53 molar (35 complete, 1 8 partial) and 24 nonmolar (13 hydropic, 11 nonhydropic) conceptuses. Nuclear suspensions were analyzed by both flow and image cytometry and there was excellent correlation (96%) in the classification of DNA di ploid, triploid, and tetraploid cases using these two methods. DNA plo idy analysis revealed a high proportion of tetraploid nonmolar concept uses (42%) and complete moles (47%). The majority of partial moles wer e triploid (89%). Tissue sections from all cases were also studied by image cytometry to identify the cellular subpopulations (decidua, vill ous stromal cells, inner trophoblast, and extravillous trophoblast) wi th abnormal DNA content. In the triploid cases, all of the villous cel l subtypes had an abnormal DNA content consistent with the development of partial moles from a triploid conceptus. In contrast, the majority of tetraploid cases showed high proliferative activity of the extravi llous trophoblast whereas the other villous cell subtypes were diploid . These results suggest that tetraploid complete moles may arise from a diploid conceptus with the development of tetraploidy related to pol yploidization of the hyperplastic extravillous trophoblast. Tissue sec tion image cytometric DNA analysis can aid in our interpretation of pl oidy results and our understanding of the biology of molar pregnancies .