2015 Annual Meeting
SC25-Diagnosis of Gestational Trophoblastic Diseases
Room CC 206, March 26 2015, 8:00am to 11:30am
Pei Hui, Brigitte Ronnett
LAST PRESENTATION The diagnosis of gestational trophoblastic diseases, particularly hydatidiform moles, poses a significant challenge to practicing pathologists. Routine monitoring of early pregnancies has resulted in presentation at earlier gestational ages than traditionally encountered, making recognition of molar pregnancies more difficult in the modern era. Furthermore, morphologic diagnosis alone continues to suffer from significant variability in interobserver reproducibility. Consequently, diagnosis of many molar pregnancies, particularly early complete hydatidiform moles and all ages of partial hydatidiform moles requires ancillary techniques to improve accuracy and guide clinical management. Gestational trophoblastic tumors, including placental site trophoblastic tumor and epithelioid trophoblastic tumor, also pose diagnostic challenges due to their rarity and frequent involvement of unusual anatomic locations. There has been substantial refinement in recent years in the histological criteria and ancillary techniques available for the diagnosis of gestational trophoblastic diseases. Immunohistochemical analysis of expression of imprinted genes such as p57 and PCR-based short tandem repeat (STR) DNA genotyping are modern ancillary diagnostic tools with powerful discriminatory capability in the diagnosis and subtyping of hydatidiform moles. P57 immunohistochemistry readily identifies all complete hydatidiform moles, even the subtle early forms. STR genotyping is capable of specifically diagnosing complete and partial hydatidiform moles and can also distinguish molar from non-molar specimens. This molecular technique is superior to traditional determination of ploidy by flow cytometry and fluorescence in situ hybridization (FISH). Categories of attendees who will benefit most from this short course include general practicing pathologists, pathologists with subspecialty interests in gynecologic or molecular genetic pathology, pathology trainees (pathology residents, gynecologic pathology and molecular genetic pathology fellows), and academic investigators with interest in gestational trophoblastic disease. A syllabus and advanced study material will be posted on the USCAP website for review by pre-registrants prior to the meeting. After the meeting, participants will receive web access to the PowerPoint presentations given during the USCAP Annual Meeting. Upon completion of this educational activity, the participants should be able to:
- Review diagnostic criteria for hydatidiform moles and challenging gestational trophoblastic tumors;
- Explain the methods of p57 immunohistochemistry and DNA genotyping for subtyping of gestational trophoblastic diseases;
- Illustrate application of these techniques with case-based examples. The goals are to familiarize practicing pathologists with the value of these techniques and promote understanding of the biology and genetics of gestational trophoblastic diseases.