Sclerotic bone metastasis: radiologic-pathologic correlation

Radiographic appearances were correlated with histologic findings in sclerotic bone metastases. For this purpose, undecalcified ground sections were made from lumbar vertebrae obtained at 12 autopsies. The primary tumor sites were the prostate gland in five cases, the breast in three, the lung in two, the stomach in one, and the urinary bladder in one. After Villanueva bone staining and methyl methacrylate embedding, 1-mm-thick ground sections were made for low-kilovoltage contact radiography. In sclerotic bone metastases, new bone is deposited on preexisting trabeculae and in the intertrabecular spaces, forming lacy networks. The radiographic indications of these histologic changes are trabecular thickening, marginal obscurity (the "silhouette" sign), and homogeneous dense sclerotic change. The silhouette sign in bone is a new concept, one that is helpful when the changes in density are not reliable.