HSD3B1 immunoreactivity was detected in intermediate trophoblast and syncytiotrophoblast in 21 early placentas, 18 complete hydatidiform moles, 67 trophoblastic tumors, including placental site trophoblastic tumors, epithelioid trophoblastic tumors, and choriocarcinomas, and 28 tumorlike lesions including placental site nodules and exaggerated placental site.