Epithelioid Trophoblastic Tumor: Review of a Rare Neoplasm of the Chorionic-Type Intermediate Trophoblast

Abstract

We present a brief review of epithelioid trophoblastic tumor, a rare trophoblastic neoplasm derived from chorionic-type intermediate trophoblastic cells that typically presents in reproductive-age women between 1 and 18 years following a previous gestation. Histologic features include a nodular growth pattern of monomorphic, epithelioid cells within a hyaline matrix. Areas of necrosis and mitotic activity (0–9 mitoses per 10 high-power fields) are additional features of this neoplasm. Positive immunostaining for p63 and cytokeratin, frequent location in the lower uterine segment and endocervix, as well as the epithelioid appearance can lead to confusion with squamous cell carcinoma. Inhibin-α is typically expressed, as well as focal, more variable expression of other trophoblastic markers including β-human chorionic gonadotropin, human placental lactogen, placental alkaline phosphate, and Mel-CAM (CD148). The clinical behavior of this rare form of gestational trophoblastic disease is difficult to predict. Although most cases follow a benign course following resection, there is a potential for metastatic disease.

Keratoacanthoma-like nodules as first manifestation of metastatic epithelioid trophoblastic tumor

“…Epithelioid trophoblastic tumor is an exceedingly rare tumor, seen mostly in reproductive-aged women [6]; it can be a sequel of any gestational event. Approximately one-third of cases arise following a spontaneous abortion or hydatidiform mole, whereas the majority occur after a full-term pregnancy [2,5,7]. The average interval from the antecedent gestational event to presentation varies, ranging from two months to as long as 18 years [2,4,5].…”

“…Approximately one-third of cases arise following a spontaneous abortion or hydatidiform mole, whereas the majority occur after a full-term pregnancy [2,5,7]. The average interval from the antecedent gestational event to presentation varies, ranging from two months to as long as 18 years [2,4,5]. Epithelioid trophoblastic tumor can present in both intrauterine and extrauterine sites [2,6].…”

“…The lung is the most common extrauterine site, accounting for 19% of cases [2]. The most common presentation is with abnormal vaginal bleeding, although the presentation in some cases relates to metastases in lung, vagina, or broad ligament [2,5,6,8]. At the time of diagnosis, serum β-HCG levels are elevated but generally do not exceed 2500mIU/mL [2,[4][5][6]8].…”

“…The neoplastic cells are small and epithelioid, with eosinophilic-to-clear cytoplasm. The cells are arranged in a monomorphic pattern of nests and cords, embedded in a hyaline matrix [4,5,8]. Although the immunohistochemical staining patterns of the reported cases are not uniform [8], inhibin alfa, cytokeratin AE1/AE3, EMA, and other trophoblastic markers including β-HCG, human placental lactogen (HPL), and placental alkaline phosphatase are commonly expressed [2,5].…”

“…Epithelioid trophoblastic tumor (ETT), first described in 1998 [3], is the most recent addition to GTD. With approximately 100 cases reported until recently [4], it is a form of GTD arising from chorionic-type intermediate trophoblastic cells [2,5]. Although metastasis is known to occur in ETT, cutaneous metastases have not been previously reported.…”