Magnetic Resonance Imaging and Computed Tomography Findings of Vertebral Osteosarcoma in a Cat

Abstract

ABSTRACT. An 8-year-old female Persian cat with a gait disorder was brought to our hospital. Pelvic limb mobility had gradually reduced over the preceding 3 months, then rapidly deteriorated 2 weeks before consultation. Signs also occurred in the thoracic limbs. With a tentative diagnosis of neural disease, magnetic resonance imaging and computed tomography were performed. T1-weighted imaging showed isointensity in the seventh cervical vertebra, while T2-weighted imaging revealed hypointensity. Contrast-enhanced T1-weighted imaging revealed a uniformly enhancing mass. Extirpation of the mass relieved the clinical signs, leading to disappearance of the neurological signs. The histopathological examination suggested osteosarcoma. The diagnosis of spinal tumors is more difficult than that of tumors of the appendicular skeleton, because the radiographic diagnosis is difficult, and various diseases are suspected from the neurological signs. Radiologic evaluation of human patients who present with osseous vertebral lesions often includes radiography, computed tomography (CT), and magnetic resonance imaging (MRI). Because of the complex anatomy of the vertebrae, CT is more useful than conventional radiography for evaluating lesion location and analyzing bone destruction and condensation [18]. On the other hand, MRI has been found to be valuable in evaluating lesion location and volume, revealing tumor extent, defining its relationship with the vertebral canal, and showing tissue specificity [7,21]. Moreover, a detailed differential diagnosis can be performed based on the MRI signal [10]. It has been suggested that early diagnosis of vertebral tumors (primary and metastatic) may improve survival [6].Tumors rarely invade cat bones, with an estimated bone tumor incidence of 4.9/100,000 cats [5,8]. Osteosarcoma accounts for approximately 70-80% of malignant primary bone tumors in cats, and it less frequently involves the axial skeleton than the appendicular skeleton [4,8]. Only a few studies have reported vertebral osteosarcoma [11,13,16]. Few studies have reported MRI and CT findings for vertebral osteosarcoma, and more detailed data have not been reported [13].We report herein the case of a cat with cervical vertebral osteosarcoma involving the epidural area and compressing the spinal cord. Surgery was performed after MRI and CT. In the present case, the postoperative course was good. To the best of our knowledge, the detailed findings of MRI or CT for vertebral osteosarcoma in cats have not been published. The clinical signs, imaging findings, and postoperative course for this case are presented.An 8-year-old, neutered female Persian cat weighing 2.9 kg was brought to our hospital with a gait disorder. Ataxia of the pelvic limbs had developed and gradually deteriorated over the preceding 3 months. Signs had also been observed in the thoracic limbs, with rapid deterioration over the previous 2 weeks. On consultation, the cat's general condition was good. However, the right thoracic limb showed inversion. Hematological da...

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