Utility of p57 protein(KIP2) in molar disease to determine its androgenetic origin

OBJECTIVE: To determine, qualitatively and semiquantitatively, the expression of p57 protein in different trophoblastic cell populations of hydatidiform mole and anembryonic pregnancy. STUDY DESIGN: We performed an observational study of the histopathologic and immunohistochemical findings of 48 cases of hydatidiform mole and 2 anembryonic pregnancies. The histologic samples stained with hematoxylin-eosin were reviewed blindly by 3 pathologists to establish a diagnosis and compare it to the previous one. Afterward, immunohistochemical staining was performed using a polyclonal antibody on paraffin-embedded, formalin-fixed tissue sections. The nuclear staining was assessed in 5 cell types: villous mesenchyme, cytotrophoblast, syncytiotrophoblast, intervillous trophoblast and decidua. RESULTS: The degree of agreement between the previous histologic diagnosis and the current one was excellent (kappa = 0.702). The sensitivity was 82.6% for complete and 84% for partial mole. On immunohistochemical analysis, the degree of agreement was low (kappa = 0.2). The sensitivity was 53.9% for complete mole and 59.1% for partial mole. The cell population with the least expression for p57 was the cytotrophoblast. The results for anembryonic pregnancies remained the same. CONCLUSION: Immunohistochemistry with p57 is a useful method to differentiate complete from partial mole, which is important to establish the prognosis of the patient.