Presentation
Patient with known osteosarcoma metastases presents for follow-up CT chest.
Patient Data
Expansile lesion right posterior fifth rib producing osteoid matrix with invasion adjacent spinal canal displacing the spinal cord to the left. Azygous vein thrombus likely represents tumor extension via draining intercostal veins. The right atrial mass likely represents a metastasis.
Chest X-ray obtained 6 months prior to CT chest shows the right fifth rib metastasis.
Two views of the right distal femur obtained 2 years prior to the CT chest show a lesion within the distal femoral diaphysis producing an osteoid matrix and a periosteal reaction. This was the patient's known osteosarcoma.
Case Discussion
The most common cardiac mass is thrombus, but in this case, in a patient with known osteosarcoma metastatic to the right fifth rib, the azygous vein filling defect likely represents tumor thrombus, resulting from hematogenous spread from intercostal veins draining the metastasis. The right atrial mass likely represents further hematogenous spread via the superior vena cava.