Short tandem repeat polymorphism analysis for primary peritoneal choriocarcinoma: A case report and literature review

The peritoneum is an extremely rare site for primary choriocarcinoma development. Primary peritoneal choriocarcinoma could be either gestational or nongestational, whereas it is straightforward to ascribe uterine or tubal choriocarcinoma to the gestational origin. Herein, we report a case of primary peritoneal choriocarcinoma that is genetically diagnosed as a gestational subtype originating from an occult complete hydatidiform mole. A 46-year-old female patient with two-time induced abortion histories underwent emergency laparotomy under clinical suspicion of ruptured tubal pregnancy. Laparotomy revealed a hemorrhagic tumor in the left mesosalpinx with apparently intact left ovary and fallopian tube. The excised tumor was pathologically diagnosed as choriocarcinoma. Multiplex short tandem repeat polymorphism analysis revealed an androgenetic/homozygous genotype tumor, identifying its origin as a complete hydatidiform mole. Our literature review of nine primary peritoneal choriocarcinoma cases, including ours, highlighted the importance of tumor genotyping in differentiating between gestational and non-gestational subtypes and identifying the causative pregnancy.