Page 339 - Atlas of Small Animal CT and MRI

3.4

Neoplasia

Extradural neoplasia CT features of primary bone tumors include hetero­
geneous osteolysis of affected bone with periosteal and
Juxtavertebral neoplasia endosteal reactive bone formation. Amorphous tumor
Malignant soft‐tissue neoplasms that arise adjacent to new bone may also be present in osteoblastic tumors
the vertebral column can invade vertebrae and the verte­ (Figures 3.4.5, 3.4.6, 3.4.7). 2,3
bral canal. Such neoplasms are often mesenchymal in MR features include altered anatomic margins and T1
origin and include hemangiosarcoma, fibrosarcoma, and T2 hypointensity in regions of reactive and tumor
myxosarcoma, liposarcoma, and synovial tumors new bone formation. When the tumor mass includes a
(Figures 3.4.1, 3.4.2, 3.4.3). significant vascular soft‐tissue component, that region
will have variable T1 and T2 intensity and can heteroge­
Neoplasia arising from bone neously contrast enhance (Figure 3.4.7). 4,5
Benign primary bone tumors
The clinical significance of benign bone tumors, such as Plasma cell tumors
vertebral osteomas and osteochondromas, often depends Plasma cell neoplasms arise from malignant proliferation
on whether they encroach on the spinal cord or disrupt of B‐lymphocytes, and they may occur as solitary plasma­
the structural integrity of the vertebral column. Benign cytomas or multiple myeloma. Multiple myeloma typically
bone tumors are usually highly mineralized, smoothly affects bone, including vertebrae, ribs, pelvis, skull, and
margined, and have CT attenuation and MR intensities proximal or distal aspects of long bones, while plasmacy­
similar to those of normal dense bone (Figure 3.4.4). 1 tomas may occur in the skin, mucosa, gastrointestinal
tract, and bone. Plasmacytomas of the vertebral column
Malignant primary bone tumors generally arise from a single vertebra but can involve
Primary bone tumors arising from the vertebral column adjacent segments. Multiple myeloma is multifocal and
include osteosarcoma, chondrosarcoma, and fibrosar­ polyostotic and is usually widely distributed within both
coma and typically have aggressive imaging features. axial and appendicular bone.
Those tumors with significant osteoid production will CT and MR are superior to survey radiography for
appear predominantly osteoproductive or have osteopro­ determining the presence and size of vertebral plasma
ductive/osteolytic components, while others may have a cell tumors. CT features of plasmacytoma include
6
predominantly osteolytic appearance. Tumors arise from osteolysis, often associated with preservation of at least
a single vertebra, but reactivity or invasion of adjacent part of the cortical margin, and pathologic fractures are
vertebrae may occur. Extension into the vertebral canal common. Tumor mass can also breach the cortical
can cause spinal cord compression, and pathologic frac­ margin and encroach on the vertebral canal, causing
ture can occur because of loss of structural integrity of extradural spinal cord compression. Plasmacytomas are
the vertebral body. soft‐tissue attenuating and mildly to markedly enhance

Atlas of Small Animal CT and MRI, First Edition. Erik R. Wisner and Allison L. Zwingenberger.
© 2015 John Wiley & Sons, Inc. Published 2015 by John Wiley & Sons, Inc.
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