Gestational trophoblastic disease

The non-villous forms of gestational trophoblastic disease (GTD) include a wide range of morphologic different lesions and cover a wide range of differential diagnosis. Choriocarcinomas (CCA) represent the most malignant form displaying a dimorphic pattern with proliferation of syncytio- and zytotrophoblast. An early start of chemotherapy is of great prognostic impact. Placental site nodule (PSN) and exaggerated placental site (EPS) are non-neoplastic lesions of the intermediate trophoblast without tumorous appearance, whereas placental site trophoblastic tumor (PSTT) and epitheloid trophoblastic tumor (ETT) represent tumorous neoplasms with a potential for local invasion and metastases. PSNs are incidental findings of highly polymorphic cells. In EPS chorionic villi are almost present, endometrial glands and spiral arteries are completely engulfed by intermediate trophoblastic cells without necroses. In PSTT the monomorphic, occasional multinucleated giant cells separating individual muscle fibers and charactersitically blood vessel walls are extensively replaced by trophoblastic cells and fibrinoid material. The ETT consists large necrotic areas with hyalinisation. Typically small blood vessels with preserved walls are located within the center of glycogen-rich monomorphous proliferation of trophoblastic cells.