Bone metastasis

Bone metastases, or metastatic bone disease, is a class of cancer metastases that results from primary tumor invasion to bone. Bone-originating primary tumors such as osteosarcoma, chondrosarcoma, and Ewing's sarcoma are rare. Unlike hematological malignancies that originate in the blood and form non-solid tumors, bone metastases generally arise from epithelial tumors and form a solid mass inside the bone. Bone metastases cause severe pain, characterized by a dull, constant ache with periodic spikes of incident pain.