Epithelioid trophoblastic tumor in male patients with germ cell tumor: A clinicopathologic analysis of five cases

Epithelioid trophoblastic tumor (ETT) is an extremely rare chorionic-type neoplasm in the testis, with only seven cases reported in the literature. Here, we report five cases of testicular ETT from a single institution, constituting the largest series of this rare tumor to date. The patients had a mean age of 44 years (range, 20-68 years). Four patients had a previous history of testicular germ cell tumor (GCT) treated with chemotherapy, and they developed ETT in metastatic sites in a mean of 11 years (range, 3-15 years) after the initial diagnosis of testicular GCT. Only one patient had ETT in the testis. Three patients had a normal serum beta-human chorionic gonadotropin (β-hCG) level, and two patients had a level that was slightly elevated, but far below that typically seen in patients with choriocarcinoma. ETT was characterized by a proliferation of intermediate trophoblastic cells with abundant eosinophilic cytoplasm, and the tumors frequently had coagulative necrosis with eosinophilic debris, mimicking keratinizing squamous cell carcinoma. The trophoblastic phenotype of ETT was supported by its immunoreactivity for trophoblastic markers, including GATA-3 (3 of 3 cases tested), α-inhibin (3/4), p63 (3/5), and β-hCG (3/4). ETT was also positive for cytokeratin (4/4) and GCT marker SALL4 (3/3). Despite surgery and chemotherapy, two patients died of disease 17 months after ETT diagnosis, and three patients were alive with metastatic disease at a mean of 20 months (range, 15-28 months). Our results demonstrate that ETT may be an aggressive disease associated with distinct pathologic features and poor clinical outcome.