Abstract
This retrospective study describes the MRI features of extradural spinal neoplasia in 60 dogs and seven cats to identify potential distinguishing features between tumor classes and individual tumor types within each class. In dogs, mesenchymal tumors were most common (48%), with undifferentiated sarcomas being the predominant tumor type. Round cell neoplasms were second most common (35%), with lymphoma and multiple myeloma/plasma cell tumor comprising the majority of cases. Only two benign tumors were identified. In cats, lymphoma was most common (5/7), with one case of mesenchymal neoplasia and one case of metastatic carcinoma. Despite some overlap, certain imaging features were able to help prioritize differential diagnoses. The combined features that predicted round cell neoplasia (84%) included the preservation of vertebral shape, homogeneous contrast enhancement, and lesion centering on bone. The combined features that predicted mesenchymal neoplasia (73%) included altered vertebral shape, heterogeneous contrast enhancement, and lesion centering on paraspinal soft tissues. Round cell neoplasms were more likely to have cortical sparing, preservation of overall shape, lesion centering on bone, small soft tissue tumor size, and homogeneous contrast enhancement. Both epithelial and mesenchymal neoplasms were more likely to have cortical lysis, a cavitary component to the soft tissue mass and medium to large soft tissue mass size. The findings of this study can aid in prioritizing differential diagnoses in cases of extradural spinal neoplasia in cats and dogs, which can impact case management, but tissue sampling remains the gold standard for definitive diagnosis.
Highlights
Spinal tumors are benign or malignant proliferation of cells that can result in compression or invasion of the spinal cord, meninges, paraspinal soft tissues, and/or nerve roots and can be associated with clinical signs of spinal cord dysfunction and pain [1, 2]
The individual magnetic resonance imaging (MRI) features more likely to be seen with round cell neoplasia were cortical sparing, preservation of overall shape, lesion centering on bone, small soft tissue tumor size, and homogeneous contrast enhancement
The combination of features predictive of round cell neoplasia was the preservation of overall shape, homogeneous contrast enhancement, and lesion centering on bone, whereas alteration of overall shape, heterogeneous contrast enhancement, and lesion centering on paraspinal soft tissues were predictive of mesenchymal neoplasia
Summary
Spinal tumors are benign or malignant proliferation of cells that can result in compression or invasion of the spinal cord, meninges, paraspinal soft tissues, and/or nerve roots and can be associated with clinical signs of spinal cord dysfunction and pain [1, 2]. Based on the anatomic location, spinal neoplasia can be classified as extradural, intradural-extramedullary, or intramedullary [2]. Extradural tumors are the most common spinal neoplasia in cats and dogs and include primary bone neoplasms (e.g., osteosarcoma, fibrosarcoma, chondrosarcoma, and hemangiosarcoma), MRI Features of Extradural Neoplasia round cell neoplasms (e.g., multiple myeloma, lymphoma, and plasma cell tumors), primary tumors arising from paraspinal soft tissues (e.g., liposarcoma, mast cell tumor, and myxosarcoma), and metastasis, commonly carcinomas [2,3,4,5,6]. Peripheral nerve sheath tumors can occur in extradural, intradural-extramedullary, and intramedullary locations [2]
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