[Placental site trophoblastic tumor. Morphology, differential diagnosis and prognosis].

A placental-site trophoblastic tumor is a rare neoplasia that is derived from the cells of the intermediate trophoblast. Morphological, biochemical, and Doppler ultrasound findings are presented regarding differential diagnosis using material from three recent cases. Essentially, placental-site trophoblastic tumors can be diagnosed if infiltration of the myometrium is seen by a monomorphic trophoblastic proliferation that is not interrupted by decidual cells. Necrosis and hemorrhages are not features of placental-site trophoblastic tumors. However, there is a peculiar behavior towards the uterine vasculature as spiral arteries are dilated and transformed the same way as occurs at the site of physiological implantation of pregnancy. It appears that as a result of this phenomenon there is a characteristic finding in ultrasound. Examination of this type of tumor demonstrates cystic spaces that can be defined as blood vessels by their Doppler signal. In two of the three cases a hysterectomy was performed, and criteria for the assumption of malignant placental-site tumors are therefore presented. However, only the mitosis rate seems to possess some predictive value.