Placental site trophoblastic tumor and epithelioid trophoblastic tumor: Clinical and pathological features, prognostic variables and treatment strategy.

Placental site trophoblastic tumor [PSTT] and epithelioid trophoblastic tumor [ETT] are the rarest gestational trophoblastic neoplasias, developing from intermediate trophoblast of the implantation site and chorion leave, respectively. PSTT and ETT share some clinical-pathological features, such as slow growth rates, early stage at presentation, relatively low βhCG levels and poor response to chemotherapy. The mortality rate ranges from 6.5% to 27% for PSTT and from 10% to 24.2% for ETT. Advanced stage, long interval between antecedent pregnancy and diagnosis, and presence of clear cells are the independent prognostic variables for PSTT, and they may be similar for ETT. Hysterectomy can represent the only therapy for early disease, whereas adjuvant chemotherapy should be reserved to patients with poor risk factors, such as an interval from the antecedent pregnancy >4 years, deep myometrial invasion or serosal involvement. Few cases of fertility-sparing treatment in young women have been reported. An individualized multidisciplinary approach, including chemotherapy and debulking surgery with abdominal and/or extra-abdominal procedures, is warranted for advanced disease. EP/EMA and TP/TE are the preferred regimens in this setting. Immunohistochemistry has sometimes shown expression of EGFR, VEGF, MAPK, PDGF-R and PD-L1, and therefore investigational studies on biological agents targeting these molecules are strongly warranted for chemotherapy resistant-disease.