Gynecologic Pathology: SY12-3 IMMUNOHISTOCHEMICAL AND MOLECULAR ADJUNCT TECHNIQUES IN DIFFERENTIAL DIAGNOSIS OF MOLAR LESIONS.

Extensive use of ultrasound in early pregnancy has given rise to increased diagnostic dilemma, particularly the differential diagnosis of early complete mole, partial mole and abnormal nonmolar villous lesions. The rare entities of placental mesenchymal dysplasia, twin pregnancy with one complete mole further pose problems. Overdiagnosis of hydatidiform mole in ectopic pregnancy should also be avoided.Molecular cytogenetic studies, besides enhancing our understanding of pathogenesis, also facilitate diagnosis and management. Laboratory techniques including microsatellite analysis, flow cytometry, in situ hybridization, sequencing, comparative genomic hybridization, and imprinting gene studies have been applied. Vast majority of complete moles are diploid and purely androgenic while most partial moles are triploid having excessive paternal genome with maternal contribution. Adjunct techniques, such as p57kip2 immunohistochemistry as well as ploidy and microsatellite analysis, have become more commonly applied to facilitate diagnosis of GTD. Molecular cytogenetic studies are also useful in distinguishing gestational and non-gestational trophoblastic choriocarcinoma with implication on chemotherapy regimes.However, we should understand clearly the diagnostic pattern and limitation of such tests to avoid misinterpretation. The basic prerequisite of processing adequate or all evacuated material for histopathological evaluation as well as correlation with clinical, radiological and biochemical findings remains the most important diagnostic approach.