Abstract

Background: The examination of morphological features of gestational products accounts as a core diagnostic process, especially for the distinction of complete hydatidiform mole (CM) from Partial Mole (PM) cases. Nevertheless, subjective evaluation of the traditional histopathological criteria might occur with substantial interobserver variability.

Objective: To assess the utility of p57^kip2 immunohistochemical (IHC) expression in distinguishing the CM from PM cases.

Materials and methods: This study was a cross-sectional analysis conducted entirely among 34 patients, including those cases with molar pregnancies and product of conception after uterine evacuation. All cases were recruited between January-July 2018 into a Gynecology and Obstetrics Department. Together with the histomorphological assessment, we performed p57^kip2 IHC staining in all the specimens.

Results: The histological diagnostic categories were as follows: CM (n=12), PM (n=8), and placenta and nonmolar product of conception group (n=14), based on previously reported criteria and IHC. Accordingly, the morphological complete mole diagnosis was consistent with p57^kip2 IHC, displaying cytotrophoblast and villous stromal cells with a negative stain in 9 out of 12 observed compelete specimens. However, one case had aberrant p57^kip2 expression and two others were morphologically concerned, having a mild degree of villous edema and greater scalloping morphology. The later cases confirmed as PMs based on IHC p57^kip2 positive staining. For PM, almost all cases histologically had consistent IHC findings with positive p57^kip2 immunostaining in cytotrophoblast and villous stromal cells. Two cases were lacked p57^kip2 marker positivity and considered as CM albeit with a milder degree of trophoblast hyperplasia. All products of conception and hydropic abortion showed fewer villi formation and positive p57^kip2 immuno-reactivity.

Conclusion: This study further confirms the importance of p57^kip2 immuno-staining as an ancillary test with the traditional histopathological criteria to distinguish complete mole from other mimic cases.

Keywords: Hydatidiform mole; Hydropic pregnancy; Immunohistochemistry; p57^kip2