Synovial myxoma in the vertebral column of a dog: MRI description and surgical removal.

A 12 yr old castrated male mixed-breed dog presented with a 2 wk history of progressive tetraparesis. Neurologic deficits included a short-strided choppy gait in the thoracic limbs and a long-strided proprioceptive ataxia in the pelvic limbs. Withdrawal reflexes were decreased bilaterally in the thoracic limbs. Signs were consistent with a myelopathy of the caudal cervical/cranial thoracic spinal cord (i.e., the sixth cervical [C] vertebra to the second thoracic [T] vertebra). A mass associated with the C6-C7 articular facet on the left side was identified on MRI of the cervical spinal cord. The lesion was hyperintense to spinal cord parenchyma on T2-weighted images, hypointense on T1-weighted images, and there was strong homogenous contrast enhancement. Significant spinal cord compression was associated with the lesion. The mass was removed through a C6-C7 dorsal laminectomy and facetectomy. Histopathology of the mass was consistent with a synovial myxoma of the articular facet. A postoperative MRI showed complete surgical resection. Albeit rare, synovial myxomas should be included in the list of differential diagnoses for neoplasms affecting the vertebral columns in dogs.

Magnetic resonance imaging features of feline intracranial neoplasia: retrospective analysis of 46 cats.

The purpose of this retrospective study was to determine the magnetic resonance imaging (MRI) characteristics of feline brain tumors and to determine whether these characteristics can be used to accurately predict the histologic diagnosis. MRI scans of 46 cats with histologically confirmed brain tumors were reviewed, including 33 meningiomas, 6 lymphomas, 4 gliomas, 2 olfactory neuroblastomas, and 1 pituitary tumor. MRI features including axial origin, shape, location, signal intensity, contrast enhancement, peritumoral edema, and mass effect were reviewed and characterized for each tumor type. Tumor shape, axial origin, contrast enhancement, and degree of peritumoral edema aided in the identification of tumor type. Meningiomas were always extra-axial and were most often ovoid with marked contrast enhancement and mild peritumoral edema. Gliomas were always intra-axial with ring enhancement and generally caused more peritumoral edema than other tumors. The brain tumor was detected on MRI in 45 (98%) cats. Two blinded independent reviewers correctly identified 82% of all of the tumor types on the basis of MRI appearance alone. Thus, MRI is an excellent diagnostic tool for the detection of brain tumors in cats, and it provides important information to aid in the diagnosis of tumor type.

Feline intracranial neoplasia: retrospective review of 160 cases (1985-2001).

The purpose of this study was to determine the frequency of different tumor types within a large cohort of cats with intracranial neoplasia and to attempt to correlate signalment, tumor size and location, and survival time for each tumor. Medical records of 160 cats with confirmed intracranial neoplasia evaluated between 1985 and 2001 were reviewed. Parameters evaluated included age, sex, breed, FeLV/FIV status, clinical signs, duration of signs, number of tumors, tumor location(s), imaging results, treatment, survival times, and histopathologic diagnosis. Most of the cats were older (11.3 +/- 3.8 years). Primary tumors accounted for 70.6% of cases. Metastasis and direct extension of secondary tumors accounted for only 5.6 and 3.8% of cases, respectively. Twelve cats (7.5%) had 2 or more discrete tumors of the same type, whereas 16 cats (10.0%) had 2 different types of intracranial tumors. The most common tumor types were meningioma (n = 93, 58.1%), lymphoma (n = 23, 14.4%), pituitary tumors (n = 14, 8.8%), and gliomas (n = 12, 7.5%). The most common neurological signs were altered consciousness (n = 42, 26.2%), circling (n = 36, 22.5%), and seizures (n = 36, 22.5%). Cats without specific neurological signs were common (n = 34, 21.2%). The tumor was considered an incidental finding in 30 (18.8%) cats. In addition to expected relationships (eg, meninges and meningioma, pituitary and pituitary tumors), we found that lesion location was predictive of tumor type with diffuse cerebral or brainstem involvement predictive of lymphoma and third ventricle involvement predictive of meningioma.