Gestational trophoblastic disease (GTD) refers to a group of proliferative disorders originating from placental trophoblasts. Histologically, it can be classified into the following categories:
- Molar pregnancy: Includes complete hydatidiform mole, partial hydatidiform mole, and invasive hydatidiform mole.
- Gestational trophoblastic neoplasia (GTN): Includes choriocarcinoma, placental site trophoblastic tumor (PSTT), epithelioid trophoblastic tumor (ETT), and mixed trophoblastic tumors.
- Tumor-like lesions: Includes exaggerated placental site reaction and placental site nodule/plaque.
- Abnormal (non-molar) villous lesions.
Although invasive hydatidiform mole is histologically classified as a borderline or tumor of uncertain behavior, its clinical presentation, diagnosis, and management principles are similar to those of choriocarcinoma. As a result, it is grouped together with choriocarcinoma under the term gestational trophoblastic neoplasia in clinical practice. Lesions confined to the uterus are referred to as non-metastatic trophoblastic tumors, whereas lesions extending beyond the uterus are classified as metastatic trophoblastic tumors. Placental site trophoblastic tumor and epithelioid trophoblastic tumor differ significantly from gestational trophoblastic neoplasia in terms of clinical presentation, disease progression, and management; therefore, they are categorized separately. Tumor-like lesions and abnormal (non-molar) villous lesions represent purely morphological changes and usually do not require clinical intervention.
The vast majority of trophoblastic tumors originate from gestation and are referred to as gestational trophoblastic tumors. A small proportion arises from germ cells in the ovaries or testes, and in very rare cases, they result from somatic cell tumors differentiating into choriocarcinoma. These are known as non-gestational trophoblastic tumors. This section specifically discusses gestational trophoblastic tumors.
To be continued