The aim of this study is to investigate the etiology of fallopian tubal choriocarcinoma and evaluate the impact of surgical treatment on the prognosis of this patient.
Fallopian tubal choriocarcinoma is a highly malignant trophoblastic tumor that can originate from pregnancy or non pregnancy. The difference between gestational and non gestational choriocarcinoma is very important, as the latter has a poor prognosis and requires more aggressive treatment. STR genotyping can assist in the identification of trisomy/monosomy syndrome and double male triploid. DNA polymorphism analysis at several STR loci is a reliable method to distinguish between gestational and non gestational tumors. The p57 [KIP2] gene is paternal imprinted and maternal expressed, and its protein product can serve as a substitute marker for the maternal nuclear genome. The combination of the two can make accurate diagnosis [4–6].
The difference between gestational and non gestational choriocarcinoma is very important because the latter has a poor prognosis and needs more active treatment.
In this case, the clinical course of the patient is characterized by 45 years old, 24 years since the previous pregnancy. The time interval from the patient's last menstrual period to the tubal mass confirmed as choriocarcinoma is very short. These medical histories are important to determine the origin of the disease. In this case, choriocarcinoma may initially develop in the fallopian tube rather than the previous hydatidiform mole (HM). It also may be gestational choriocarcinoma from ectopic pregnancy. Immunohistochemical staining were used on the tissue in order to make a definite diagnosis. The result showed p57 (-) (Fig. 2) which means the tumor lacked maternal contribution. STR test were further used which result showed that it was bisexual monoandrogynous triploid (Fig. 3), indicating that the tumor contained maternal alleles. In rare cases, when complete HM was accompanied by trisomy 11 (one more maternal chromosome 11) or partial HM was accompanied by loss of maternal chromosome 11, the immunohistochemical staining results of p57 will be opposite to the aforementioned (because the imprinted gene CDKN1C is located on chromosome 11). This opposite conclusion can be corrected through ploidy analysis and STR genotype detection. Therefore, we still consider it as gestational fallopian tubal choriocarcinoma.
For the clinical treatment of gestational fallopian tubal choriocarcinoma, a unified standard has not been formed at this stage. Due to the characteristics of tubal histology, fallopian tubal choriocarcinoma is easy to invade the blood and early metastasis early. The treatment is a comprehensive treatment mainly based on chemotherapy, supplemented by surgery, often using 5-fluorouracil + actinomycin combination chemotherapy [7], and the therapeutic effect is still satisfactory. Ober and Maier reported that adjuvant chemotherapy increased the survival rate of choriocarcinoma in the fallopian tubes from 13–94%, but their study was published nearly 30 years ago. In addition, they also described five cases that could be cured by single surgical resection. A case report described that it was confirmed as androgenic primary tube choriocarcinoma after evaluation by combining p57 [KIP2] immunostaining and STR analysis in 2011, and was cured through surgery without adjuvant chemotherapy [8].
Due to postoperative complications β- HCG is rapidly decreasing, we are considering whether adjuvant chemotherapy is needed in this situation. This patient was diagnosed with ectopic pregnancy rupture upon admission and underwent salpingectomy on the affected side. After 6 days of surgery, blood was collected β- HCG decreased from 235303 mIU/ml before surgery to 5855 mIU/ml, and decreased to normal range 6 weeks after surgery without chemotherapy. Follow up monitoring β- HCG levels are normal for 3 years. This case report for the first time describes a rare case of triploid tube choriocarcinoma that was confirmed as rare after surgical treatment and cured without chemotherapy, evaluated by combining p57 [KIP2] immunostaining and STR analysis.
According to relevant literature reports at home and abroad, patients with tube choriocarcinoma often undergo exploratory laparotomy due to "ectopic pregnancy", and postoperative chemotherapy is supplemented based on the examination results. Due to atypical clinical manifestations and similar symptoms to ectopic pregnancy, the two are easily confused, and differential diagnosis should be made by combining β-HCG level, MRI, vaginal ultrasound, and color Doppler flow imaging.
Therefore, we believe that for this type of gestational fallopian tubal choriocarcinoma is particularly difficult to differentiate from ectopic pregnancy and requires exploratory laparotomy, chemotherapy may not be supplemented after the first surgical removal of the tumor. Subsequently, imaging follow-up and rigorous apple monitoring can be conducted to avoid any risk of metastasis and recurrence. It must meet the following conditions: there is no transfer in the early stage, the β-HCG shows an exponential decline and drops to the normal range within 6–8 weeks. The number of surgical cured cases without adjuvant chemotherapy is currently rare, and similar cases still need to be accumulated to provide a basis for our imagination.