Two well-defined non-neoplastic conditions of intermediate trophoblast are placental site nodule (PSN) and exaggerated placental site reaction (EPS). PSN is a proliferative lesion of intermediate trophoblast of the chorionic type, whereas EPS is a reactive process consisting of intermediate trophoblast at implantation site. Clinicopathologically, both lesions are incidental findings, associated with either a prior pregnancy or a concurrent gestation. They are microscopic in size and generally not detectable by imaging studies. Histologically and immunohistochemically, EPS and PSN have histological and cytological features simulating their neoplastic counterparts, i.e, placental site trophoblastic tumor (PSTT) and epithelioid trophoblastic tumor (ETT), respectively. 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. Atypical placental site nodule (APSN) is a recently recognized premalignant condition with a risk to progress to gestational trophoblastic tumors.