Clinical characteristics and outcomes of extrauterine epithelioid trophoblastic tumors

Epithelioid trophoblastic tumor (ETT) derived from intermediate trophoblasts is one type of gestational trophoblastic neoplasia (GTN), and it accounts for less than 2% of all gestational trophoblastic diseases (GTD). Extrauterine ETT is extremely rare, and there is currently no consistent strategy for its treatment and management. Therefore, the aim of the study is to analyze and summarize the clinicopathologic features of extrauterine ETT with or without metastasis.

The Web of Knowledge, Google Scholar, EMbase, congress of library, and PubMed were searched for extrauterine ETT without primary uterine lesions. All available data were extracted from published case reports or serial case reports, and then, the clinical and pathological characteristics were analyzed.

Twenty-two clinical studies consisting of 27 patients diagnosed with extrauterine ETT, according to the given inclusion and exclusion criteria, were included in the study. A total of 27 cases of extrauterine ETT were identified. Of these cases, four (14.81%) were located in the lungs, three (11.11%) in the ovaries, two (7.41%) in the vagina, and eight (29.63%) patients had other primary lesions. The patients originated from different continents, with 59% located in Asia and 26% in North America. Among 23 patients, the antecedent pregnancy prior to the diagnosis was full-term in 12 cases, abortion in 6 cases, hydatidiform mole in 3 cases, and invasive mole in 1 case. From the available antecedent information on pregnancy, the median interval from pregnancy to diagnosis of extrauterine ETT was 4 years. Additionally, the median gravidity and para of the patients was three times and two times, respectively. The median hCG titer was 14,374 mIU/mL in 5 patients, and the mean β-HCG titer was 3,724,805 mIU/mL in 14 patients. For all patients, the disease was confined to extrauterine ETT at diagnosis. From the available information, 20 cases were successfully treated by extraction of local lesions, and 12 cases received chemotherapy. Diagnosis was confirmed by histological tests. The Ki-67 staining ranged from 8.7 to 80%, and tumors were positive for hCG, PLAP, EMA, and p63.

In this study, we observed that abnormal levels of serum hCG titers and the local presentation of lesions with varying intervals after antecedent term pregnancy were the most common presenting features of extrauterine ETT. In addition, we found that the extraction of extrauterine lesions was needed for the treatment of extrauterine ETT. Of course, the follow-up was also important.