Malignant Teratoid Medulloepithelioma in a Dog

Abstract

Absfrucf.A malignant teratoid medulloepithelioma that arose from the ciliary body was found in an adult Beagle. The anterior part contained relatively well-differentiated tumor cells, cartilage, and ganglion cells. These structures were interpreted as teratoid formations derived from the embryonic anlage of the medullary epithelium. The more posterior part was highly anaplastic and invasive. A transitional area contained neural rosettes of the Flexner-Wintersteiner type. This tumor is rare in both man and animals.Intraocular ciliary body tumors appear to be uncommon in man and in animals [7, 181. Of the tumors reported in dogs and other animals, however, ciliary body tumors represent a significant number of primary intraocular neoplasms [3, 191. Malignant teratoid tumor of the ciliary epithelium is rare in both animals and man. Its variable morphology makes diagnosis difficult but elucidates the embryogenesis of the ciliary epithelium. Clinical HistoryA 4-year-old Beagle bitch was examined for evaluation of a 'white pupil' in the left eye. This had been first noted 3 months previously. There was no history of ocular tumors or other malignancies in the litter. Three weeks before examination, the eye became proptotic. There was periorbital swelling, and hemorrhagic discharge was seen from a perforated cornea. A solid white mass partially filled the anterior chamber and extended behind the lens as well. Enucleation with partial removal of the orbital content was subsequently performed. Four years later there is no evidence of orbital recurrence.Gross examination showed a firm globe with an irregular solid mass penetrating the cornea at the limbus and at the posterior part of the globe. The anterior segment, vitreous cavity, retina, sclera and orbit were filled with a firm tumor. Microscopic examination

Retinoblastoma in the eye of a llama (Llama glama)

“…As stated previously, there remains considerable debate as to the existence of spontaneous retinoblastomas in animals, even though one well documented case was described in a dog 1,2 . Neoplasms resembling retinoblastomas have been more frequently diagnosed as medulloepitheliomas 1,2,8–18 . Medulloepitheliomas can be classified as benign or malignant, and teratoid or nonteratoid 24 .…”

Canine ocular neoplasia: a review

“…Some areas may have features resembling ciliary processes or retina. Medulloepitheliomas may be termed teratoid when the neoplasm contains heterotopic elements that are not normal derivative of the ocular embryonic development . Medulloepitheliomas are immunoreactive for TERT with limited immunopositivity for cytokeratin, vimentin and CD99.…”

“…The prognosis for life is generally good, although metastasis is reported, and the prognosis for the globe is poor as enucleation is required in most cases …”

Iridociliary epithelial tumors in 100 dogs and 17 cats: a morphological study

“…The epithelium of the ciliary body and iris is derived from neuroectoderm by expanding forward from the margins of the optic cup. Tumors of primitive neuroectoderm have been reported in young dogs and are designated medulloepithelioma 6 –8 . Peiffer 2 presents the features important to distinguish between medulloepithelioma and iridociliary epithelial tumors.…”