Epithelioid trophoblastic tumour

Epithelioid trophoblastic tumor (ETT) is a gestational trophoblastic disease with about 110 case reports in the literature. It is a trophoblastic tumor of neoplastic chorionic type associated with the intermediate trophoblast.

Signs and symptoms

 * Vaginal bleeding: The most common presenting symptom is vaginal bleeding, which is associated with mild elevation of serum β hCG (< 2,500 IU/L)
 * Amenorrhea.

Gross appearance

 * There is deep infiltration of the surrounding structures by cystic hemorrhagic masses or discrete nodules.
 * Necrosis is present with white to tan-brown cut surface with hemorrhage.
 * Ulceration (common finding)
 * Fistula (common finding)

Microscopic appearance

 * Nodular, well circumscribed, focal infiltrative at the periphery.
 * Uniform, mononucleate tumor cells are arranged in nests and cords.
 * Tumor nests are associated with eosinophilic, fibrillar, hyaline-like material.
 * Extensive necrosis with irregular contours.
 * Calcification (common finding)
 * Metaplastic endocervical or endometrial surface epithelium into squamous-like epithelium.

Locations
Common locations are:
 * Uterus
 * Lower uterine segment (40%)
 * Cervix (31% of cases)
 * Lungs (19% of cases)

They may rarely develop in
 * Vagina
 * Broad ligament
 * Fallopian tubes
 * Other pelvic organs

Treatment
Epithelioid trophoblastic tumors (ETTs) are resistant to chemotherapy, but an immunotherapy drug called dostarlimab treats gestational trophoblastic neoplasia. ETT is a form of GTN. Stage I disease is treated with hysterectomy, while metastatic disease is treated with surgery and chemotherapy.

Prognosis
Metastasis occur in 25% of cases and 10% die of the disease. Mitotic count of > 6/10HPF is an unfavorable prognostic factor.