P57Kip2 immunostaining, a diagnostic marker in differentiating complete hydatidiform mole from its mimics

Abstract

Background and objective: The distinction of hydatidiform mole from hydropic abortion remains a problem because of interobserver and intraobserver variability. This study aimed to determine the utility of p57Kip2 as a diagnostic marker in differentiating complete hydatidiform mole from its mimics.Methods: A total of 97 formalin fixed paraffin embedded material including forty cases of complete hydatidiform mole, 36 cases of partial hydatidiform mole and 21 cases of hydropic abortion were selected randomly from the files of histopathology laboratory of Maternity Teaching Hospital in Erbil. The samples were reviewed by two pathologists, afterward; immunohistochemical staining was performed by using a p57Kip2 marker. We considered p57Kip2 positive only if nuclear p57Kip2 staining was identified in at least 10% or more of all in a tissue section. Results: Negative immunostaining was seen in 77.5% of the complete hydatidiform mole in both villous cytotrophoblast and stromal cells. In contrast, 86.1% of partial hydatidiform mole showed positive immunostaining for p57Kip2. All cases of hydropic abortion 100% were positive for p57Kip2 immunostaining. In all gestations, p57Kip2 was strongly expressed in decidua which served as internal positive control. The concordance between the initial histological diagnosis and p57Kip2 immunostaining was statistically significant (P <0.001). Conclusions: p57Kip2 immunostaining is a highly sensitive and specific marker for diagnosis and classification of hydatidiform mole. p57Kip2 staining has the advantage of differentiating hydropic abortuses from the complete hydatidiform mole.