Step 1: Gestational trophoblastic neoplasia (GTN) refers to the malignant or persistent forms of gestational trophoblastic disease that follow any pregnancy event.
Step 2: The recognised gestational trophoblastic neoplasms are invasive mole, choriocarcinoma, placental-site trophoblastic tumour, and epithelioid trophoblastic tumour. These all behave as neoplastic conditions.
Step 3: A partial hydatidiform mole is a form of molar pregnancy (gestational trophoblastic disease), not a neoplasm in the GTN category. Among the given options, the partial mole is the entity that does not belong to gestational trophoblastic neoplasm, so it is the correct answer.