RESUMEN
Placental site trophoblastic tumour (PSTT) is a rare form of trophoblastic disease accounting for < 2% of all gestational trophoblastic neoplasms. Most of the cases follow a normal pregnancy and a small number have a preceeding molar pregnancy or spontaneous abortion. It can occur as early as several weeks or as late as 15 years after normal delivery, molar pregnancy or abortion. Excessive intermediate trophoblastic activity is the most important diagnostic criterion of this tumour originating from non villous trophoblast. But the possibility of a PSTT should be considered when there is excessive intermediate trophoblastic activity despite the presence of chorionic villi as in the present case. This case report highlights the unusual features like rarity of the tumour (< 2%), occurrence following spontaneous abortion which happens only in a minority of cases, and presence of chorionic villi in the tumour despite the fact that the tumour is of non villous trophoblastic origin.