Background: Recent developments in genetic analysis allow determination of the origin of choriocarcinoma (ie, gestational or nongestational), which helps determine the strategy for clinical treatment of the disease.
Case: We present a case of ovarian choriocarcinoma forming a huge ovarian mass 40 days after the patient's last menstrual period. Deoxyribonucleic acid microsatellite analysis of the tumor revealed that it contained a single maternal and two paternal alleles at several independent loci, consistent with the tumor resulting from ovarian pregnancy of a partial hydatidiform mole.
Conclusion: This is the first description of an ovarian pregnancy of a partial hydatidiform mole-derived ovarian choriocarcinoma.