A case is reported of a man, sixty-six years old, who had a biopsy-proved osteogenic sarcoma of the ilium in the absence of Paget's disease and, after seven months, osteoblastic and osteolytic lesions in the spine and pelvis as well as metastases to the lungs. At autopsy, a large mass arising from the left iliac crest was identified as osteogenic sarcoma. Several pleural and pulmonary metastases of this tumor were present. Microscopically, a well differentiated adenocarcinoma of the prostate was also identified with metastases in the vertebrae, pelvis, and tissues adjoining the osteogenic sarcoma.

The following were considered as possible explanations for the findings in this case: (1) both neoplasms were unrelated; (2) they originated independently but their growth was influenced by each other's presence; (3) both neoplasmas arose independently from a common stimulus; (4) both neoplasmas originated from the same cells, but underwent two patterns of differentiation; and (5) the tumors were related in a cause-and-effect manner, that is, metastases from the adenocarcinoma of the prostate stimulated the development of an osteogenic sarcoma through their effect on bone.

Future cases showing osteoblastic bone lesions in the presence of osteogenic sarcoma should bring to mind the possibility of a complicating metastatic carcinoma.