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Main : Vet Neurol Neurosurg J : Volume 2 : Issue 1 : Case Study 2 |
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Veterinary Neurology and Neurosurgery Journal (VNNJ) Case Study 2Vet Neurol Neurosurg J. January 2000;2(1):1.
Full Text Article (What's Your Diagnosis?)May, 2000 Background Physical Examination Neurology Examination Results Tests Performed Summary Background This dog was seen at the Veterinary Medical Teaching Hospital, University of California Davis. We are grateful for the skillful participation by the Radiology Service and Clinical Laboratories of the VMTH during the diagnostic investigation of this dog. Signalment Six year old castrated male, mixed breed dog. History Two-month history of progressive muscle atrophy of the left side of the head. Medication The dog is not presently receiving medication. Past Medical History No significant past medical history. Physical Examination
Neurological Examination Results
Cranial Nerves
Tests Performed Hematology, Chemistry and Urinalysis Clinical Chemistry Panel Results
Hemogram Results
Imaging Tests - Thoracic Radiographs Click on the image to see a larger view
Magnetic Resonance Imaging (MRI) Results Click on the image to see a larger view
Pathology Gross Pathology* * This dog had progressive signs involving both motor and sensory trigeminal function. Imaging revealed a contrast-enhancing mass within the calvaria with distortion of the brain stem. The mass also extended out one or more foramina to involve peripheral part(s) of the trigeminal nerve. The owners declined treatment and requested euthanasia. Necropsy was performed by the University of California Davis Veterinary Medical Teaching Hospital Pathology Service. Gross necropsy findings of significance Respiratory system: Multiple pulmonary masses including a 3.0 x3.5 x 1.0 cm firm, raised, mottled white, yellow, red, gelatinous mass in right caudal lung lobe and a 1.1 x 1.0 cm mottled yellow-white mass in the left caudal lung lobe. When sectioned, the latter mass was found to contain a small amount of yellow, creamy material. Musculoskeletal system: marked atrophy of left temporal and masseter muscles. Nervous system: There was a 3.5 x 2.0 x 1.0 cm firm tubular, shaped mottled tan-red mass on the extradural surface of the left, ventral brainstem. The mass appeared to be connected to the fifth, sixth and/or seventh cranial nerve(s). It extended through the trigeminal nerve canal in the petrous ridge, involved the nerve tissue rostral thereto, and extended out along the nerves where they emerged through their respective foramina. The adjacent brainstem and the trigeminal nerve roots were slightly compressed.(see figure below).There were no other significant gross lesions except for the muscle atrophy which had been noted clinically and multiple pulmonary masses, one of which yielded a small amount of yellow creamy material when incised. Click on the image to see a larger view
Histopathology
Summary This dog had progressive motor and sensory trigeminal nerve dysfunction. Imaging had revealed a contrast-enhancing mass within the calvaria with distortion of the brain stem. The mass extended out one or more foramina to involve peripheral part(s) of the trigeminal nerve. The owners declined treatment and requested euthanasia. Necropsy was performed by the University of California Veterinary Medical Teaching Hospital Pathology Service. The gross characteristics of the mass are described separately. Histologically,* the mass consisted of a densely cellular monomorphic population of neoplastic spindle shaped cells extending to the margins examined. The cells were arranged in streaming intersecting patterns. The cells had variably sized elongate, spindle shaped nuclei which tapered at either end. Heterochromatin was evenly distributed without obvious nucleoli. Cells were embedded in an eosinophilic matrix without any defined cytoplasmic borders. There were up to 2 mitotic figures per high powered field [400X mag]. Occasional lymphocytes and plasma cells were infiltrated within the neoplastic tissue. There were large intervening areas of necrosis. (See histopathology sections of this case.) Thus, grossly and microscopically, the mass conformed closely with descriptions of malignant nerve sheath tumors of the cranial nerves of dogs as in Summers, et al.1 Although frequently referred to as "malignant schwannomas" it is often difficult to identify the cell of origin of these tumors. In dogs, the incidence of these tumors is higher in spinal nerves than in cranial nerves. Among the latter, the trigeminal nerve is affected most often. Pulmonary metastases, as in this case, are unusual, but provide additional evidence of the malignancy of the tumor. * VNN is grateful to Prof. Robert J. Higgins for examining the microscopic sections and providing the description above. Reference 1. Summers BA, Cummings JF and de Lahunta A, Veterinary Neuropathology (p. 473). Mosby, St Louis Baltimore Berlin Boston Carlsbad Chicago London Madrid Naples New York Philadelphia Sydney Tokyo Toronto 1995. ISBN 0-8016-6328-8
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Main : Vet Neurol Neurosurg J : Volume 2 : Issue 1 : Case Study 2 |
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General: Alert and responsive; Body condition score=6. (System range=1-9)
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