Placental site trophoblastic tumour and epithelioid trophoblastic tumour.

Placental site trophoblastic tumour (PSTT) and epithelioid trophoblastic tumour (ETT) are the rarest subtypes of gestational trophoblastic disease (GTD). Their diagnosis is complicated and lacks specific and sensitive tumour markers. They are slow-growing tumours and can occur months to years after any type of antecedent pregnancy. The primary treatment for localised disease is hysterectomy. However, extra-uterine invasion and/or metastasis occur in about one-third of cases and still cause death in a small number. Most patients are young; hence, fertility preservation is a consideration. The major obstacle for prognosis is chemotherapy resistance. The current understanding of these tumours remains elusive and no randomized controlled trials have been done. Even those centres treating a large number of patients with GTD will infrequently manage PSTT/ETT. In this review, we assess progress in the understanding of the disease and discuss four main clinical challenges - establishing conformity of practice, devising a risk-adapted approach to clinical management, establishing long-term follow-up data and evaluating therapies for poor prognosis and multi drug-resistant patients.