Combination of immunohistochemistry and ploidy analysis to assist histopathological diagnosis of molar diseases.

Background: Differential diagnosis between hydropic abortion, partial mole and complete mole is still a challenge for pathologists but really important for patient management.
Material and Method: In this study, we have evaluated 111 products of conception from the first trimester. Histological analysis was made according to the main diagnostic histopathological features described in the literature and the cases were categorized in hydropic abortus (HA), partial mole (PM) and complete mole (CM). Immunohistochemistry was performed using monoclonal antibody against p57(kip) protein a putative paternally imprinted inhibitor gene and DNA ploidy was analysed in all cases by image cytometry.
Results: All 23 HAs presented a diploid DNA content and were p57(kip2) positive. From the 28 CMs, 12 cases (43%) were diploid and 16 cases (57%) were tetraploid but no expression of p57(kip2) was found with positive internal controls. From the 60 PMs, 58 cases were positive for p57(kip2) expression and 53 cases (88%) were triploid, 6 cases (10%) tetraploid and 1 case (2%) diploid.
Conclusion: This study on 111 cases of early pregnancies confirms the usefulness of immunohistochemistry and cytometry but demonstrates the importance of the combination of both techniques to assist histology for the best reliable diagnosis.