Magnetic resonance imaging findings of the primitive neuroectodermal tumour in lumbosacral spinal cord in a cat.

A 5-year-old, castrated, male domestic short-haired cat presented with neurological deficits in the pelvic limbs, back pain and dysuria. Magnetic resonance imaging showed a mass lesion caudal to the L4 vertebrae. In addition, suspected haemorrhage was observed at the cranial aspect of the mass. There was no evidence to support the presence of extravertebral intrusion or vertebral body, osteolysis. Dorsal laminectomy and durotomy were performed to debulk the intraspinal mass. Histopathological and immunohistochemical assessment revealed a primitive neuroectodermal tumour (PNET). To our knowledge, this is the first report to describe the clinical and pathological features and imaging diagnosis of intraspinal PNET without extraspinal invasion in a cat.

Intraocular neuroectodermal embryonal tumor in two rabbits.

Spontaneous intraocular tumors are rarely reported in rabbits, despite their widespread use as laboratory animals. We describe two cases of intraocular neuroectodermal embryonal tumors, formerly primitive neuroectodermal tumors, in young rabbits. Histologically, both tumors exhibited prominent rosette or pseudorosettes, consistent with the histomorphology seen in human tumors. The neuroectodermal subtype is supported by immunoreactivity for the neuronal markers, SRY-box transcription factor 2, microtubule-associated protein 2, neuronal nuclear protein, and neuron-specific enolase. In one of the rabbits, there was metastasis to the contralateral conjunctiva. Intraocular neoplasms can occur in young rabbits and eyes with refractory disease should be enucleated for clinical management.

Malignant ocular teratoid medulloepithelioma in two cats.

Medulloepithelioma is a type of rare primitive neuroectodermal tumour. Most medulloepitheliomas are intraocular and they have been most frequently reported in horses and dogs. A single feline case has been reported but the teratoid form has not been previously reported in cats. Two cats presented with rapidly expanding intraocular masses and ophthalmic examination revealed vascularized uveal tumours extending into the anterior chamber and vitreous chamber. Following enucleation, histopathological examination of each case revealed a focally extensive infiltrative neoplasm that replaced the uveal tract, with retinal detachment and scleral vascular invasion. Rosettes, medullary tubes and heterotopic tissue were present. During follow-up periods of 3.4 and 8.8 years, no evidence of orbital recurrence or metastasis was found in either cat. To the best of our knowledge, these are the first case reports of teratoid medulloepithelioma in cats. Although the risk of metastasis cannot be excluded, as in other species, these findings support enucleation as a curative intervention.

Ocular teratoid medulloepithelioma in a northern red-shouldered macaw: case report and literature review.

A 4-mo-old northern red-shouldered macaw (Diopsittaca nobilis) was admitted to the veterinary hospital of the Arruda Câmara Zoo, in the State of Paraiba, Brazil, for investigation of an orbital mass. Given rapid progression and lack of response to treatment, the bird was euthanized, and an autopsy was performed. Histologically, the mass consisted of a retrobulbar invasive tumor characterized by tubular and rosette-like structures, with interspersed heteroplastic tissues, such as aggregates of neuroglial cells and islands of hyaline cartilage. The tumor was immunopositive for pancytokeratin, GFAP, NSE, and S100. These findings were compatible with an ocular teratoid medulloepithelioma, a neoplasm best described in humans but also reported rarely in young cockatiels and African Grey parrots.

Clinical behavior of intraocular teratoid medulloepithelioma in two-related Quarter Horses.

The objective of this paper is to describe clinical behavior, histopathologic features, and immunohistochemical staining of two-related horses with intraocular teratoid medulloepithelioma. Two-related Quarter Horses with similar intraocular masses presented to the UF-CVM Comparative Ophthalmology Service for evaluation and treatment. The first horse, a 3-year-old gelding, had glaucoma and a cyst-like mass in the anterior chamber. Enucleation was performed. Histopathology revealed a teratoid medulloepithelioma. The tumor was considered to be completely excised. Fifteen months later, the gelding presented with swelling of the enucleated orbit and local lymph nodes with deformation of the skull. Cytology revealed neuroectodermal neoplastic cells. Necropsy confirmed tumor metastasis. Six weeks later, a 9-year-old mare, a full sibling to the gelding, presented for examination. An infiltrative mass of the iris and ciliary body was found that extended into the anterior, posterior, and vitreal chambers. Uveitis was present, but secondary glaucoma was not noted. Enucleation was performed and the histopathologic diagnosis was also teratoid medulloepithelioma. The mare has had no recurrence to date, 2 years following enucleation. Metastasis of intraocular teratoid medulloepithelioma is possible. Staging is recommended in cases where the diagnosis of teratoid medulloepithelioma is confirmed. Surveillance of full siblings is recommended until more information regarding etiology is known.

Case of a miniature dachshund with a primitive neuroectodermal tumor confined to the forebrain region treated with a combination of surgery and chemotherapy.

A miniature dachshund aged 9 years and 7 months with a history of polyuria/polydipsia and depression was referred. General physical and neurological examinations revealed no obvious abnormalities. MRI of the brain revealed a large space-occupying lesion in the left frontal lobe. This was surgically removed and pathologically diagnosed as a primitive neuroectodermal tumor (PNET). Although the clinical signs had been improved, follow-up MRI revealed recurrence of the tumor. Lomustine was administered, but 1 year after surgery, the dog exhibited cluster seizures and died. This is the first reported case of a dog with PNET confined to the forebrain region treated by surgical resection in combination with chemotherapy, as observed by repeated follow-up MRI.

Primitive neuroectodermal tumour in a striped dolphin (Stenella coeruleoalba) with features of ependymoma and neural tube differentiation (Medulloepithelioma).

Primary brain tumours in cetaceans are rare with only four reported cases of intracranial tumours in the scientific literature. A juvenile female, striped dolphin live-stranded at Whitepark Bay, Co Antrim, Northern Ireland, UK, and died after an unsuccessful attempt at refloatation. Necropsy examination revealed a large, soft, non-encapsulated friable mass, which expanded and replaced the frontal lobes, corpus callosum and caudate nucleus of the brain and extended into the lateral ventricles, displacing the thalamus caudally. Microscopically, this comprised moderately pleomorphic neoplastic cells arranged variably in dense monotonous sheets, irregular streams, ependymal rosettes, 'ependymoblastomatous rosettes' and multilayered to pseudostratified tubules. Liquefactive necrosis, palisading glial cells, haemorrhage and mineralization were also observed. Immunohistochemically, the neoplastic cells expressed vimentin but not S100, glial fibrillary acidic protein, cytokeratin, neuron-specific enolase or synaptophysin. Based on these findings a diagnosis of primitive neuroectodermal tumour was made. Monitoring and recording such cases is crucial as neoplasia may be related to viral, carcinogenic or immunosuppressive chemical exposure and can ultimately contribute to assessing the ocean health.

Primary primitive neuroectodermal tumors of the retina and ciliary body in dogs.

We describe the clinical, histological, and immunohistochemical features of primary intraocular primitive neuroectodermal tumors in eight dogs. Four of eight tumors exhibited histological features similar to human retinoblastomas characterized by Flexner-Wintersteiner rosettes, and fleurettes, and demonstrated variable immunoreactivity for retinal markers opsin, S-antigen (S-Ag) and interphotoreceptor retinoid-binding protein (IRBP). All dogs with tumors displaying histological and immunohistochemical features of retinal differentiation were ≤2 years of age. All tumors diagnosed as medulloepitheliomas (n = 4) did not display histological and immunohistochemical features of retinal differentiation and were present in dogs 7 years or older. Age of onset, in conjunction with immunohistochemistry for opsin, S-Ag, and IRBP, is an important aid in the differentiation of primary, primitive neuroectodermal tumors arising within the canine ciliary body, retina, and optic papilla.

Benign intraocular teratoid medulloepithelioma causing glaucoma in an 11-year-old Arabian mare.

CASE DESCRIPTION: An 11-year-old Arabian mare was presented for investigation of a visible, pale-colored intraocular mass in the right eye. CLINICAL FINDINGS: An intraocular mass was detected clinically and ultrasonographically as originating from the superior temporal quadrant of the ciliary body and iris and causing secondary glaucoma. The echodense mass was occupying the majority of the vitreous chamber and extended into the anterior chamber. The left eye appeared normal. TREATMENT AND OUTCOME: Enucleation was recommended for therapeutic and diagnostic purposes. No adjuvant treatment was given. Histopathological examination demonstrated a benign intraocular teratoid medulloepithelioma located at the ciliary body. Immunohistochemical studies showed that neoplastic cells were positive for vimentin, S-100 protein, neuron-specific enolase (NSE), and nestin and negative for glial fibrillary acidic protein (GFAP). Electron microscopy revealed abundant cellular matrix and blood vessels surrounding tumor cells, which had indented, round to oval nuclei. There were also apoptotic bodies and cells containing melanosomes of variable shape and size. Eight years later, the horse has had no recurrence and maintains normal vision in the left eye. CLINICAL RELEVANCE: This is the first report of a benign teratoid intraocular medulloepithelioma in an adult horse and the ultrastructural and immunohistochemical characterization of a teratoid medulloepithelioma in this species.

Spontaneous cerebellar primitive neuroectodermal tumor in a juvenile cynomolgus monkey (Macaca fascicularis).

A neoplastic mass compressing the left cerebellar hemisphere and hindbrain was observed at trimming in a 3½-year-old male cynomolgus monkey from a control dose group. Microscopically, the neoplastic mass was nonencapsulated, invasive, and showed two morphological patterns. The predominant area consisted of densely packed undifferentiated, polygonal to spindle cells arranged in vague sheets supported by a scant fibrovascular stroma. The other area was less cellular and composed of round neoplastic cells separated by eosinophilic fibrillar material. Immunohistochemical staining for vimentin, synaptophysin, glial fibrillary acidic protein, neuron-specific enolase, neurofilament, and S-100 confirmed the presence of primitive undifferentiated neuroectodermal cells and some cells with neuronal or glial differentiation. On the basis of histopathology and immunohistochemical findings, a diagnosis of cerebellar primitive neuroectodermal tumor with neuronal and glial differentiation was made. Primitive neuroectodermal tumors are rare in animals including nonhuman primates; this is the first published report in this species.

Retrobulbar primitive neuroectodermal tumor in a squirrel monkey (Saimiri sciureus).

BACKGROUND: A 2.8-year-old female captive-bred common squirrel monkey (Saimiri sciureus) showed exophthalmos of the right eye, and the eye was surgically enucleated. A tumor mass was found in the eye. METHODS: Formalin-fixed tumor samples were examined histopathologically and immunohistochemically for diagnosis. RESULTS: The retrobulbar tumor mass adhered to the sclera and infiltrated the choroid. Histopathologically, tumor cells were pleomorphic, arranged in a sheet pattern, and mimicked primitive neuroectodermal cells. The tumor cells were strongly positive for precursor neuronal cell markers (beta III tubulin, neuron-specific enolase, vimentin, nestin, doublecortin, oligo2, and S-100), but negative for mature cell markers (cytokeratin, neurofilament, and glial fibrillary acidic protein) and a retinoblastoma marker (rhodopsin). CONCLUSIONS: This is the first reported case for the retrobulbar location of primitive neuroectodermal tumor in non-human primates.

A primitive neuroectodermal tumor with extension into the cranial vault in a dog.

This paper reports the clinical findings, cytology, diagnostic imaging, and necropsy of an unusual case of a peripheral nervous system neoplasm which, subsequent to a 6-month clinical history, extended into the cranial vault. Necropsy and histology confirmed the diagnosis of a peripheral primitive neuroectodermal tumor.

Peripheral primitive neuroectodermal tumour in a lumbar vertebra and the liver of a dromedary camel (Camelus dromedarius).

A 9-year-old castrated male dromedary camel developed weakness and ataxia, progressing to sternal recumbency and hindlimb paralysis. Necropsy revealed multiple liver tumours and a mass in the 3rd lumbar vertebra, compressing the spinal cord. The hepatic and vertebral masses consisted of uniform sheets of primitive cells, with perivascular pseudorosettes and small numbers of neuroblastic Homer-Wright rosettes. Immunohistochemically, the tumour cells were uniformly positive for vimentin and variably positive for neuron-specific enolase and glial fibrillary acidic protein. The histopathological and immunohistochemical findings indicated a peripheral primitive neuroectodermal tumour (pPNET) exhibiting neuroblastic, glial and ependymomatous differentiation, probably reflecting the tumour's primitive multipotential neuroepithelial nature. To the authors' knowledge, this is the first reported case in the camel of a pPNET, presumably intraosseous in origin with hepatic metastasis, and morphologically similar to Ewing's sarcoma in man.

Central primitive neuroectodermal tumour with ependymal differentiation in a dog.

A central primitive neuroectodermal tumour (PNET) with ependymal differentiation was identified in an 18-month-old female Australian terrier dog that died following signs of central nervous system disease. A large space-occupying haemorrhagic mass replaced the thalamus and part of the hypothalamus of the brain. Microscopical examination revealed a tumour formed by a compact sheet of small cells that contained ependymal and perivascular pseudorosettes. Immunohistochemically, the neoplastic cells variably expressed glial fibrillary acidic protein, neuron-specific enolase, vimentin and cytokeratin, consistent with divergent differentiation of the tumour. This case is thought to represent the first description of PNET with ependymal differentiation in a dog.

Primary intraocular primitive neuroectodermal tumor (retinoblastoma) causing unilateral blindness in a gelding.

A 14-year-old gray gelding was presented for investigation of a visible, pale-colored ocular mass in the right eye. An intraocular mass was identified clinically and ultrasonographically as originating from the superior nasal quadrant of the ciliary body and retina. The mass occupied the majority of the vitreous chamber and some of the superior anterior chamber of the eye. The affected eye was blind. Following exenteration, a primary intraocular primitive neuroectodermal tumor (i.e. a retinoblastoma/medulloepithelioma), a rarely described intraocular mass in adult horses, was identified by pathologic examination. The gelding returned to normal use following a short recovery period.

Immunohistochemical properties of ocular adenomas, adenocarcinomas and medulloepitheliomas.

Ocular medulloepitheliomas, adenomas and adenocarcinomas share a common phenotype and originate from the optic cup neuroectoderm. This can make it very difficult to differentiate between these tumors histopathologically. Therefore, this study focused on identifying a combination of immunologic markers that might be used in the diagnosis of these tumors. These markers included AE1/AE3, CK7, CK20, and telomerase reverse transcriptase (TERT). Routine immunohistochemical staining was performed on 27 whole globes diagnosed with one of these tumors. The tumors that immunostained for TERT showed increasing immunoreactivity as the tumor types increased in aggressiveness. None of the tumor types were immunopositive for CK7. CK20 immunostaining was found in the adenomas but not in the adenocarcinomas or medulloepitheliomas. AE1/AE3 expression was present more consistently in the adenocarcinomas and less frequently in the adenomas. AE1/AE3 expression was present in only one of six medulloepitheliomas. Furthermore, CK20 and TERT showed inverse expression patterns, i.e. TERT increased in expression and CK20 decreased in expression with increasing aggressiveness. These results may be important diagnostic and prognostic indicators for these tumors.

Malignant nonteratoid ocular medulloepithelioma in a llama (Llama glama).

A 6-year-old female llama presented with buphthalmos of its right eye owing to the presence of an intraocular mass. The affected globe was enucleated and submitted for microscopic examination. The intraocular mass was diagnosed as malignant medulloepithelioma. Within the following months, the llama developed soft tissue masses, which completely filled the right orbital cavity and expanded the cranial portion of the right mandibular bone, and enlarged mandibular lymph nodes. Euthanasia was elected 30 months after the initial diagnosis. The carcass was submitted for postmortem examination, which revealed the presence of medulloepithelioma metastases within the right orbit, mandible, mandibular lymph nodes, lungs, liver, and mesenteric and sublumbar lymph nodes. The primary intraocular tumor and its metastases were composed of neoplastic undifferentiated neuroepithelial cells, which formed tubules, Flexner-Wintersteiner and Homer Wright rosettes, and rare solid sheets. Electron microscopy showed that tumor cells were connected by desmosome-like junctions and contained rare intracytoplasmic basal bodies. Neoplastic cells were positive for vimentin, nestin, microtubule-associated protein 1B, S-100 protein, and glial fibrillary acidic protein (GFAP). To the best of the authors' knowledge, this is the first report of a malignant nonteratoid ocular medulloepithelioma with distant metastases in a llama and of the ultrastructural and extended immunohistochemical characterization of a nonteratoid medulloepithelioma in this species.

Primitive neuroectodermal tumor in the spinal cord of a brahman crossbred calf.

A variety of embryonal tumors of the central nervous system, typically malignant and occurring in young individuals, are recognized in humans and animals. This report describes an invasive subdural but predominantly extramedullary primitive neuroectodermal tumor developing at the lumbosacral junction in a 6-month-old Brahman crossbred calf. The tumor was composed of spindloid embryonal cells organized in interlacing fascicles. The cells had oval to elongate or round hyperchromic nuclei, single to double nucleoli, and scant discernible cytoplasm. Immunohistochemical staining for neuron-specific enolase, synaptophysin, and S-100 protein and formation of pseudorosettes suggested neuronal and possibly ependymal differentiation.