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

Abstract

This case reports an eight-years-old horse that presented a unilateral tumor in the left ocular orbital region diagnosed on
the basis of clinical signs, gross anatomopathological and histopathological investigations. The affected area was exenteration
and submitted to histopathological evaluation and was diagnosed as a non-teratoid medulloepithelioma. This is a rare ocular
neoplasm that usually affects young individuals – and was composed by neuroepithelium arranged in tubules and Flexner-
Wintersteiner rosettes without presence of heteroplastic components. The animals died and was submitted to post-mortem
evaluation, revealing presence of medulloepithelioma metastases at the internal region of the head, lymph nodes, lungs, and
liver. This neoplasm usually presents a benign frame; however, the case herein described shows that it can be highly malignant
and aggressive since it can cause extensive lesions and spread metastases to visceral organs.