Spinal metastases: the obvious, the occult, and the impostors.

Spines from 832 deceased patients with a terminal diagnosis of malignant neoplasm were examined grossly, microscopically and radiographically for evidence of tumor. Gross tumor and bone destruction or sclerosis were reliable signs of obvious metastases. Occult lesions visualized on gross sagittal sections but not detectable radiographically occurred in 26% of spines with confirmed metastatic deposits. Vertebral collapse was not a reliable indicator of metastases. Collapse was not caused by neoplasm in 22% of cases. Overall, metastases were found in 36% of patients dying from neoplastic disease. Although most metastases are obvious, occult lesions not visible radiographically occur. Collapsed vertebra may be impostors simulating metastatic disease.