Non-gestational malignant placental site trophoblastic tumor of the ovary in a 4-year-old rhesus monkey.

We report a case of ovarian malignant intermediate-type trophoblastic tumor in a clinically normal, nonpregnant 4-year-old rhesus monkey (Macaca mulatta). A large solid lobulated mass replaced the right ovary and filled the pelvis. Multiple metastases were observed within the lungs and the liver. The tumor was histologically identified as predominantly composed of intermediate trophoblastic cells, without prominent hemorrhages and the classic bilaminar pattern of cyto- and syncytiotrophoblastic cells characteristic of choriocarcinoma. Immunohistochemical analysis showed the presence of placental lactogen hormone in many tumor cells and chorionic gonadotropin in a few multinucleated cells consistent with syncytiotrophoblastic differentiation. No other germ cell differentiation was identified in the pelvis mass nor in the metastases. In the absence of previous and present pregnancy, this neoplasm has to be considered as a nongestational malignant placental site trophoblastic tumor of the ovary.

Uterine epithelioid trophoblastic tumor in an African green monkey (Chlorocebus aethiops sabaeus).

A uterine mass was detected on physical exam in a multiparous African green monkey as an incidental finding, and the well-circumscribed mass was removed via hysterectomy. Histologically, the mass consisted of sheets, nests, and cords of uniform intermediate trophoblastic cells with eosinophilic or clear cytoplasm. These neoplastic cells aggregated around blood vessels, forming islands of viable tumor cells amid extensive areas of coagulative necrosis with calcification in a 'geographic' pattern of necrosis. Immunohistochemistry of the trophoblastic cells revealed strong and diffuse staining for pancytokeratin AE1/3 and p63, with weak and moderate staining for human placental lactogen and placental alkaline phosphatase, respectively. Immunohistochemical staining for smooth muscle actin, epithelial membrane antigen, and human chorionic gonadotropin was negative. Overall, the histologic and immunohistochemical features of this tumor were consistent with those of epithelioid trophoblastic tumor. This rare tumor type has not been reported previously to occur in African green monkeys.

Uterine epithelioid trophoblastic tumour in a red-tailed guenon (Cercopithecus ascanius).

Epithelioid trophoblastic tumour (ETT), a rare neoplasm of chorionic-type intermediate trophoblastic cells in the human female, was diagnosed in the uterus of a red-tailed guenon, a non-human primate. The animal, having had two live births, had a recent history of heavy vaginal bleeding. Four years after the last known pregnancy, the animal developed a large invasive mass involving the uterus, right ovary and abdominal wall. The tumour was removed surgically, but at necropsy 1.5 years later was found to have a recurrent neoplasm. Histologically, the original mass consisted of nests and cords of mononuclear intermediate trophoblastic cells whose borders were accentuated by intimately associated eosinophilic hyaline extracellular proteinaceous material. Extensive coalescing areas of necrosis with mineralization surrounding islands of viable neoplastic cells created a "geographical" pattern of necrosis. Immunohistochemical examination revealed that neoplastic cells were diffusely strongly positive for cytokeratin 18, and focally positive for human placental lactogen. The histopathological and immunolabelling patterns were consistent with ETT in human beings. This is the first reported case of epithelioid trophoblastic tumour in a non-human species.

Ovarian epithelioid trophoblastic tumor in a cynomolgus monkey.

Epithelioid trophoblastic tumor (ETT) is an unusual type of trophoblastic tumor, with features resembling carcinoma. In this study, we describe a 4-year-old cynomolgus monkey (Macaca fascicularis) showing, at necropsy, a lobulated mass replacing the left ovary and several nodular lesions within the lungs. Histologically, the mass in the ovary and lung metastases were characterized by nests of epithelioid cells, with intermingled, occasional, multinucleate tumor cells consistent with syncytiotrophoblasts and moderate amount of eosinophilic, hyaline-like material. Immunohistochemically, the tumor cells were diffusely positive for cytokeratins (AE1/AE3) and inhibin-alpha, but only focal immunoreactivity was observed for human chorionic gonadotropin, whereas placental alkaline phosphatase was always negative. On the basis of morphology and immunohistochemical reactivity, tumor cells were identified as intermediate trophoblast.