Placental site trophoblastic tumour.

Placental site trophoblastic tumour (PSTT) is a very rare and unique form of gestational trophoblastic disease (GTD). This tumour represents a neoplastic transformation of intermediate trophoblastic cells that normally play a critical role in implantation. PSTT can occur after a normal pregnancy, abortion, term delivery, ectopic pregnancy or molar pregnancy. It displays a wide clinical spectrum, and when metastatic, can be difficult to control even with surgery and chemotherapy. Unlike other forms of GTD, PSTT is characterized by low beta-hCG levels because it is a neoplastic proliferation of intermediate trophoblastic cells. Expression, however, of human placental lactogen (hPL) is increased on histologic section as well as in the serum. The most common presenting symptoms of PSTT are vaginal bleeding and amenorrhoea. Diagnosis is confirmed by dilatation and curettage (D and E) and hysterectomy but meticulous evaluation of metastasis is mandatory. Most cases are confined to the uterus but pelvic involvement, lung and other organ metastasis has been reported. Unlike other forms of GTD, the WHO prognostic score is of little help. For the PSTT patient, surgery is the primary treatment of choice. For patients desiring future childbearing, D and C and adjuvant chemotherapy is an option. Because these tumours tend to be less sensitive than other types of GTD to chemotherapy, the most successful regimen to date has been with EMA/CO or EMA/EP. Good prognosis is anticipated in cases localized to the uterus, and when the interval between antecedent pregnancy and treatment is less than 2 years. In cases with distant metastasis or delayed treatment, the outcome is dismal. Advances in chemotherapeutic regimens have improved clinical reponse in metastatic disease.