Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

518 Small Animal Radiolo g y and Ultrasono graphy
Fig. 4-55 A 5-year-old male Golden
Retriever with an ill-defined lameness
and weight loss. The lateral view
of the right elbow reveals an illdefined,
lytic lesion that lacks clearly
defined margins and involves the
proximal radius. No periosteal reaction
is evident. Similar lesions were
present in the pelvis and left tibia.
Diagnosis: Lymphoma.
Fig. 4-56 A 10-year-old male German Shepherd dog with
lameness in the left foreleg of 1 month duration. A periprostatic
cyst had been removed 5 months previously. There is a
destructive lesion involving the central portion of the radial
diaphysis. A faint periosteal proliferation is evident cranial to
this area of bony destruction (arrows). There is poor demarcation
of the lesion from the surrounding normal bone.
Increased density surrounds this area of bony destruction,
especially on the caudal proximal aspect of the ulna.
Diagnosis: Metastatic neoplasm. This was a metastatic prostatic
adenocarcinoma.
M E TA S TAT I C T U M O R S
Tumor metastases to bone may occur with tumors arising from parenchymatous organs or
primary bone tumors. 130,134,203-213 Tumor metastases to bone are more commonly metaphyseal
but occasionally may be diaphyseal. The commonly reported sites include the
femur, humerus, and tibia, although any bone may be involved and the lesion is frequently
polyostotic. The radiographic appearance of metastatic lesions varies. Metastatic lesions
may be osteolytic, osteoblastic, or mixed (Figs. 4-56 to 4-58). Soft-tissue swelling usually is