Page 303 - Canine Lameness

17.2 Neoplasia of pecific eeions 275

(A) (C) (E) (G)

(B) (D) (F) (H)

Figure 17.2 Proximal humeral osteosarcoma: (A) lateral and (B) craniocaudal radiographs display a subtle
lesion (white arrows) that may be missed without performing orthogonal views; (C, D) predominant
osteolytic changes extending throughout the proximal one‐quarter of the humerus are visible; (E, F)
osteolytic and proliferative changes extend throughout the proximal one half of the humerus; (G) osteolytic
and osteoproductive changes, irregular osseous production along the cranial aspect of the proximal
humerus, as well as a smooth periosteal reaction along the caudal aspect of the humerus; and (H)
pathologic fracture due to osteosarcoma. Note the periosteal reaction, punctate lysis of the cortices and
patchy, heterogenous, and moth‐eaten appearance to the medullary cavity of the humerus.

is the one tumor type where tumor cells are most likely to be seen in the CSF. A sample collected
from the lumbar cistern has been reported to be more likely to be diagnostic than one collected
from the cerebellomedullary cistern (Thomson et al. 1990).
Tumors of the spinal cord are categorized into intramedullary, intradural‐extramedullary, and
extradural based on their location with respect to the spinal cord tissue itself and meninges:
Intramedullary neoplasms are located within the spinal cord substance and can be primary spinal
parenchymal tumors or metastatic. Primary tumors are more common in the C6–T2 segment and are
predominantly of glial cell origin; astrocytoma and ependymoma are the most frequent but other
types reported include oligodendroglioma, undifferentiated sarcoma, choroid plexus papilloma, and