Non-teratoid ocular medulloepithelioma in an adult horse

Abstract

This is a case of medulloepithelioma in a 14-year-old mixed breed gelding horse, presenting a large abnormal mass of tissue involving the entire extension of the right eye. Ophthalmic examination showed deformation and swelling of the eye. The animal showed signs of pain on palpation of the organ, but the specific examination of the systems did not reveal any other changes. Due to the extension of the apparently neoplastic mass and the discomfort experienced by the animal, transpalpebral enucleation procedure was decided. The excised tissue was sent for histopathological analysis, wherein a neoplastic proliferation of neuroectodermal cells was noted. The neoplasm was poorly delimited, unencapsulated, infiltrative, sustained by moderate fibrovascular stroma, and formed cords and rosettes with cells arranged in palisades around the luminal structures (Flexner-Wintersteiner rosettes), suggestive of medulloepithelioma. The immunohistochemical profile was also performed, confirming the diagnosis. The neoplastic cells were immunolabeled to vimentin, S100 protein (S100), and specific neuro enolase (NSE), but not for pan cytokeratin (AE1AE3), glial fibrillary acidic protein (GFAP), and cytokeratin 8/18 (CK8/18). Five months postoperatively, the animal was healthy, without any relapse or evidence of metastasis.

A case of metastatic non-teratoid ocular medulloepithelioma in an adult horse

“…The intraocular neoplasia was probably congenital and asymptomatic until the development of secondary complications, as in the case described in young horses (18,29). There are few reports in the literature of intraocular medulloepitheliomas in older horses (15), with two cases diagnosed in 11-year-old mares, cases of teratoid medulloepitheliomas (15,18) and a 14-year-old gelding horse case of non-teratoid medulloepithelioma (23), all the three cases without metastasis (15,18,23). The case reported in this work is a case of non-teratoid medulloepithelioma of an old mare with pulmonary and hepatic metastases and with invasion of the face bones around the primary tumor.…”

“…In the medulloepithelioma cases described in horses, the recommended therapeutic procedure is enucleation of the affected eye (15,18,23,29), as was done in this reported clinical case. Although medulloepitheliomas are typically locally invasive and enucleation is usually curative, in rare cases, such as the one presented here, there may be recurrence and lymphatic and/or hematogenic dissemination (28).…”

“…In contrast to medulloepitheliomas, retinoblastomas are mainly composed of sheets of undifferentiated neuroepithelial cells (7,20). The main histological characteristic of medulloepithelioma is the formation of the Flexner-Wintersteiner rosettes (7), therefore, immunohistochemistry could be performed to confirm the suspicion of medulloepithelioma and exclude the differential diagnoses (23,29) as the neuroendocrine carcinomas and paragangliomas (26).…”

Intraocular neuroectodermal embryonal tumor in two rabbits

“…Intraocular neuroectodermal embryonal tumors (NETs) are rare and sporadically reported in dogs, cats, horses, birds and llamas. [1][2][3][4][5][6][7][8][9] As there are no reports of neuroectodermal tumors in rabbits, we describe NETs in two pet rabbits.…”