Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

694 Small Animal Radiolo g y and Ultrasono graphy
The majority of tumors that affect the vertebral column produce a lytic lesion. Some
tumors show a mixed pattern of both lysis and periosteal new bone formation (Fig. 6-40).
Rarely, increased vertebral density may be the predominant radiographic finding. 177 A paravertebral
soft-tissue mass may be visible. 157 Primary tumors usually are localized to one
vertebral body; however, they may spread to adjacent vertebrae. Collapse of the vertebra or
the adjacent disc space occurs in a small number of both primary and metastatic vertebral
tumors. 178 Multiple myeloma typically occurs with multiple lytic, well-circumscribed bony
lesions that do not have sclerotic borders (Fig. 6-41). 179 In a few cases of multiple myeloma
a diffuse loss of bone density will be seen (Fig. 6-42). Multiple myeloma also may produce
solitary or multiple destructive and proliferative lesions similar to those observed with
other vertebral neoplasms. 173,180,181 Lymphoma may produce multicentric proliferative or
destructive vertebral lesions or extradural-intramedullary spinal cord lesions. 182
Metastatic tumors often involve more than one vertebral body. Any portion of the vertebra
may be involved. Any malignant tumor may spread to the vertebrae (Fig. 6-43). 183-185
Prostatic, bladder, urethral, caudal mammary gland, and perianal neoplasias have been
Fig. 6-39 A 4-year-old Beagle from
California developed pain in the thoracolumbar
area, anorexia, and
pyrexia. There is periosteal new bone
formation with a fine linear pattern
at a right angle to the vertebral body
(arrow), as well as subtle lysis of the
ventral aspect of L2. Diagnosis:
Vertebral osteomyelitis secondary to
foxtail migration.
Fig. 6-40 An 8-year-old male
Miniature Poodle with back pain.
The lateral radiograph of the thoracolumbar
spine revealed marked loss
of bone density of T12 (white
arrow). Differential diagnoses
include primary or metastatic neoplasms
and an unusual infectious
process. Diagnosis: Osteosarcoma of
T12.