Epithelioid trophoblastic tumor

Epithelioid trophoblastic tumor (ETT) is an extremely rare type of gestational trophoblastic neoplasm (GTN) that arises from the chorionic-type intermediate trophoblast of the placenta. First described as a distinct entity in 1998, ETT most commonly occurs in women of reproductive age, typically years after a prior pregnancy, which may have been a full-term delivery, miscarriage, or molar pregnancy. The tumor primarily affects the uterus, most often involving the lower uterine segment and endocervix, though it can occasionally present at extrauterine sites including the lungs, vagina, and broad ligament. Clinically, patients most frequently present with abnormal vaginal bleeding. Serum human chorionic gonadotropin (hCG) levels are typically only mildly elevated, which can make diagnosis challenging and may lead to confusion with cervical carcinoma or other uterine tumors on histological examination. The tumor forms discrete, nodular masses that may show areas of necrosis and hemorrhage. Microscopically, ETT is characterized by nests and sheets of relatively uniform, epithelioid cells with eosinophilic or clear cytoplasm, surrounded by hyaline-like material and necrotic debris. Unlike other forms of gestational trophoblastic disease, ETT is relatively resistant to conventional chemotherapy regimens typically used for GTN. Hysterectomy remains the primary and most effective treatment, particularly for disease confined to the uterus. For patients with metastatic or recurrent disease, multi-agent chemotherapy protocols (such as EMA/CO or EMA/EP) may be employed, though response rates are lower compared to other gestational trophoblastic neoplasms. Due to its rarity, management is best guided by specialized trophoblastic disease centers. The overall prognosis is generally favorable when the disease is localized, but metastatic disease carries a significantly worse outcome, with reported mortality rates of approximately 10-25%.

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