Placental-site trophoblastic tumor with bone metastasis: A diagnostic and therapeutic challenge.

Placental-site trophoblastic tumor (PSTT) is a rare pathological entity included in the spectrum of gestational trophoblastic neoplasia (GTN). It is a neoplasia with metastatic potential that, once metastasized, has poor prognosis because the tumor tends to be less sensitive to chemotherapy. We present a rare case of gestational trophoblastic neoplasia, in which hysterectomy for persistent gestational trophoblastic disease after hydatidiform mole, revealed a primary PSTT in the uterus. Subsequently, a slight persistent elevation of the beta fraction of human chorionic gonadotropin hormone (B-hCG) during follow-up revealed the presence of bone metastases. This location is not usual from this tumor, being even more rare the case of PSTT with isolated bone metastases. Metastasic foci were only identified with PET-CT since the usual diagnostic resources were not able to do it. Finally, it is also remarkable in our case that the treatment required the confluence of chemotherapy together with immunotherapy to achieve a favorable response.