Papiloma de plexo coroide em um cão / Choroid Plexus Papilloma in a Dog

ABSTRACT

Background: Choroid plexus tumors are uncommon neoplasms derived from the neuroepithelium that covers the ventricular cavity and the central canal of the spinal cord that are characterized by papillar aspect and intraventricular growth. It occurs more commonly in dogs, but it has been reported in horses, cows, ferrets and is rare in cats. After the meningiomas and gliomas, choroid plexus tumors are the third encephalic tumors in dogs. In veterinary medicine, there are not many actual reports of this type of neoplasia, therefore, the aim of this paper was to report a case of a choroid plexus papilloma in a poodle dog. Case A six year old dog, female, poodle, was admitted at the Veterinary Hospital of the São Paulo State University Júlio de Mesquita Filho with a complaint of seizures for 15 days, blindness and head tilt to the right side. At the neurological examination, it had depression, head tilt to the right, circling and ataxia, postural reactions deficits, absent menace response, absent light pupillary reflex with mydriasis and augmented patellar reflex. The patient was submitted to blood harvest to perform CBC count and biochemical profile (renal and hepatic), which were normal. The cerebrospinal fluid analysis presented a discrete raise of proteins. The animal was treated with phenobarbital and prednisone, under suspicion of inflammatory disease or encephalic neoplasia. The patient developed a progressive paresis of the four limbs and the seizures remained unaltered. After approximately one month of the first consultation, the dog was admitted in status epileticus, without success of control. Necropsy revealed flattening of convolutions due to cerebral edema, dilatation of the lateral ventricles (hydrocephalus) and the presence of a greyish nodule, soft and measuring 0.6 x 0.8 cm in length coming out of the fourth ventricle and extending laterally between the cerebellum and brainstem and cranially to the thalamus. At the cut of the tissue, it presented a dark area at the region of the thalamus. Neoplastic tissue was composed of cuboidal to columnar epithelial cells with oval and regular nuclei, supported by richly vascular stroma, arranged in papillae. Discussion: Choroid plexus papillomas are tumors that originate in the choroid plexus epithelium. Affected dogs usually have six or more years, earlier than most brain tumors. However, cases have been observed in younger dogs, and dogs affected by carcinoma are generally older than those affected by the papilloma. In dogs, the tumor occurs most commonly in the fourth ventricle, as in the present report, but can also occur in the third ventricle and the lateral ventricles. The clinical signs in patients with choroid plexus tumors are varied depending on the location of the tumor in the central nervous system, but may include behavioral changes, ataxia, paresis, seizures, circling, cranial nerve and proprioceptive reflexes changes. Macroscopically, the choroid plexus papilloma is a well-defined mass, expansive, granular to papillary, grayishwhite to red color. Microscopically, this tumor resembles the choroid plexus and have arboriform and vascular stroma which is coated by a single layer of cuboidal to columnar epithelial cells. The findings were consistent with choroid plexus papilloma located in the fourth ventricle.