Similarly, excess mineralization seen in some cases of tumor deposits in bone is also due to inappropriate cytokine release from the tumor cells. Malignancies of various organs and tissues commonly metastasize to bone. Malignancies of breast, prostate, lung, kidney and thyroid are frequent sources of metastatic deposits in bone. Grossly, lesions replace bone and appear as soft tissue masses of varying sizes. Hemorrhage and necrosis are frequently seen.
Lesions can contain gritty areas due to reparative bone deposition within the tumor.
The tumor deposits resemble the primary tumor. In some instances, the metastasis may be more or less well differentiated than the primary focus. There is often evidence of osteoclastic activity and bone resorption in the vicinity of the tumor. Pathological fractures are fractures of bones which occur as a result of stress normally insufficient to break a bone. Robbins Pathologic Basis of Disease.