Rationale: Rare uterine choriocarcinoma can be differentiated gestational from nongestational choriocarcinoma by using short tandem repeats (STRs).
Patient concerns: A 56-year-old Taiwanese woman underwent staging surgery because of suspicion of high-grade endometrial cancer. The pathology-confirmed uterine tumor with syncytiotrophoblasts and decidual change of the endometrium was harvested.
Diagnosis: Uterine nongestational choriocarcinoma.
Interventions: The tumor specimen, the patient's blood, and her husband's blood were drawn for STRs analysis using polymerase chain reaction amplification kit. The genotype of the tumor cells was solely maternal and made the diagnosis of uterine nongestational choriocarcinoma.
Outcome: Adjuvant chemotherapy with etoposide, methotrexate, actinomycin D, cyclophosphamide, vincristine regimen achieved good response in the patient. The patient is now recurrence-free for 12 months.
Lessons: STRs aid precise classification of rare choriocarcinoma. We encourage using the method to analyze suspicious choriocarcinoma.