Malignant teratoid medulloepithelioma with brain and kidney involvement in a dog

Animal studied A tumor of the left eye with involvement of the brain and kidney was diagnosed in a 4-year-old Neapolitan mastiff. Procedure The dog presented with acute glaucoma of the left eye. Peripheral corneal vascularization and severe corneal edema obscured examination of deeper structures. Because of concurrent progressive neurologic signs the dog was euthanized and a postmortem examination was performed. The eyes, brain and samples from the lung, heart, liver and kidneys were fixed in 4% neutral buffered formalin and embedded in paraffin wax. Sections were examined by light microscopy including histochemical and immunohistochemical staining. Results The ocular tumor originated from the ciliary body and was composed of small islets and cords of poorly differentiated, oval to polyhedral cells surrounded by abundant ground substance. Areas with chondroid differentiation were observed. Rosettes were not found. Metastases with the same morphology were present in the brain and in one kidney. Conclusion An intraocular malignant teratoid medulloepithelioma with metastases to the brain and kidney is presented.