Tumor-Like Trophoblastic Conditions

Abstract

Two well-defined reactive conditions of intermediate trophoblast are placental site nodule (PSN) and exaggerated placental site (EPS) reaction (see Table 1.1 from Chap. 1). PSN is a proliferative lesion of the intermediate trophoblast at the chorionic laeve whereas EPS is a reactive process consisting of the intermediate trophoblast at implantation site. Clinicopathologically, both lesions are incidental findings and are associated with either a prior pregnancy or a concurrent gestation. They are microscopic and generally not detectable by imaging studies. Histologically and immunohistochemically, PSN and EPS have histological and cytological features simulating their neoplastic counterparts, that is, epithelioid trophoblastic tumor (ETT) and placental site trophoblastic tumor (PSTT), respectively (Int J Gynecol Pathol 20(1):31–47, 2001). Recognition by pathologists of both lesions is important as they may simulate various trophoblastic tumors and even non-trophoblastic neoplasms, such as squamous cell carcinoma.