Massive pulmonary tumor emboli in osteosarcoma occult and fatal complication

The lung is the most frequent site of metastasis in osteosarcoma, but extensive intraluminal tumor growth in pulmonary arteries is rare. Two patients with osteosarcoma in whom the tumors grew in the pulmonary artery and caused massive pulmonary emboli are reported. Histologically the tumor emboli were myxoid and different from the primary lesion and the other metastases, which were osteoblastic in one case and chondroblastic in another case. In both cases the pulmonary tumor emboli were the cause of death.