Gestational trophoblastic disease comprises a heterogeneous group of related lesions arising from abnormal proliferation of trophoblast of the placenta. The pathogenesis of gestational trophoblastic disease is unique, because the maternal lesions arise from fetal, not maternal, tissue.
The histopathology of gestational trophoblastic disease is discussed here. The epidemiology, clinical manifestations, diagnosis, and treatment of hydatidiform moles and malignant gestational trophoblastic disease are reviewed separately. (See "Gestational trophoblastic disease: Epidemiology, clinical manifestations and diagnosis" and "Gestational trophoblastic disease: Management of hydatidiform mole" and "Gestational trophoblastic neoplasia: Staging and treatment".)
- Gestational trophoblastic disease (GTD) — Lesions characterized by abnormal proliferation of trophoblast of the placenta. This category is comprised of benign, nonneoplastic lesions including placental site nodule, exaggerated placental site and hydatidiform moles as well as malignant neoplasms.
- Gestational trophoblastic neoplasia (GTN) — Gestational neoplasms include: choriocarcinoma, placental site trophoblastic tumor, epithelioid trophoblastic tumor, and invasive moles that do not resolve spontaneously. In the absence of tissue for a definitive histopathological diagnosis, disease diagnosed as a result of persistent elevation of hCG after evacuation of a molar pregnancy is termed GTN.
Most, but not all, GTD produces the beta subunit of human chorionic gonadotropin (hCG). Chromosomal abnormalities are characteristic of some GTD subtypes; assessment of DNA content enhances the diagnostic accuracy of histological diagnosis (see 'Genetics' below) [1,2].
Types of GTD — There are various histologically distinct subtypes of GTD: