Osteosarcoma in adjacent lumbar vertebrae in a dog

Abstract

An 8-year-old male Belgian Malinois was referred for evaluation of progressive caudal paresis of 2 to 3 weeks' duration. Radiography revealed a mottled appearance to the body of L4 and misshapen intervertebral foramen at L4-L5. Myelography revealed that the dye column terminated within the body of L4. Computed tomography revealed a soft tissue mass adjacent to or involving the spinal cord and L4, with complete destruction of a portion of the floor of the vertebral foramen. Small circular lesions were also noticed within the body of L3 and L5. A left-sided hemilaminectomy was performed. Histologic examination of a biopsy specimen revealed a high-grade sarcoma. Because of the poor prognosis, the dog was euthanatized. Necropsy examination revealed osteosarcoma, with lesions in L3 to L7, the sacrum, and the lungs. Metastatic lesions in adjacent bones have been termed skip metastases and the primary tumor is typically in long bones. Prognosis associated with skip metastases is similar to or even graver than that associated with pulmonary metastases. In the dog of the present report, the unusual finding of distinct foci of osteosarcoma within 5 adjacent lumbar vertebrae and the sacrum was consistent with skip metastases, potentially spread via the vertebral venous plexus.

Multipotential Osteosarcoma with Various Mesenchymal Differentiations in a Young Dog

“…Symmetrical and synchronous involvement with distal metaphyseal lesions of identical radiographic character in long bones and sparing of the visceral organs are suggestive of multicentric origin. 8,10,14,23 In this case, the three bone tumors in the right hind limb were larger and had more aggressive radiographic features than the bone tumor located in the left distal femur. Although the smaller size and less aggressive features of the lesion in the left distal femur could possibly reflect a later onset of a fourth primary bone tumor, the smaller size more likely reflects its origin as a metastatic neoplasm that arose at about the same time as that in the rib cage.…”

“…1,6,8,10 They commonly arise in the metaphyses of long bones, especially the distal femur and proximal tibia. 1,8,14,23 In such cases, it may be difficult to determine whether the neoplasm is multifocal in origin or if the lesions are caused by metastatic disease. Symmetrical and synchronous involvement with distal metaphyseal lesions of identical radiographic character in long bones and sparing of the visceral organs are suggestive of multicentric origin.…”

“…2,10,17 Osteosarcomas arise commonly in the proximal humerus, distal radius, distal femur, and proximal and distal tibia in the dog. 13,14,20,21,24 Primary osteosarcomas rarely cross joints or invade adjacent bones during early tumorogenesis, but as the tumor increases in size, both events occur more commonly. 8,21,23 Rare cases of multicentric osteosarcoma have been reported in humans and dogs.…”

“…8,21,23 Rare cases of multicentric osteosarcoma have been reported in humans and dogs. 3,8,10,14 An osteosarcoma that develops after successful treatment of another osteosarcoma lesion is termed a metachronous osteogenic sarcoma. 1,8,10 In human medicine, synchronous multicentric osteogenic neoplasms occur most commonly in children, usually under 15 years of age and carry a grave prognosis.…”

Magnetic Resonance Imaging and Computed Tomography Findings of Vertebral Osteosarcoma in a Cat

“…Evaluation of tumor type or differentiation of tumor from inflammation is impossible on radiography [9]. While bone tumors may cross a disc space, this is rare, aiding in differentiation from discospondylitis [15]. On MRI after infusion of contrast medium, tumors or inflammatory lesions are enhanced, while inflammatory lesions are unevenly enhanced [1].…”