Placental site trophoblastic tumor.

Placental site trophoblastic tumor (PSTT) is a rare neoplasm that rises from intermediate trophoblasts and commonly presents with low and variable concentration of HCG immunoactivity in serum, which can be difficult to differentiate from early stage choriocarcinoma/gestational trophoblastic neoplasm (GTN) or quiescent gestational trophoblastic disease. PSTT can occur after a normal pregnancy, spontaneous abortion, termination of pregnancy, ectopic or molar pregnancy. There is a wide clinical spectrum of presentation and behavior ranging from a benign condition to an aggressive disease with fatal outcome. Nontrophoblastic malignancies such as germ cell tumors or other tumors secreting low HCG must also be considered in the differential diagnosis. Because treatments for these conditions are different, a means of differentiating PSTT from other diagnoses is important. Surgery is the cornerstone of treatment. Chemotherapeutic regimen should be EMA/CO for first line chemotherapy; EMA/EP should be used in EMA/CO refractory cases. This article reviews the literatures on this rare but fatal disease.