The bones are the third most common site for metastases, after the liver and lungs. Bone metastases (BM) are most commonly found in areas of red bone marrow. When located in the spine, bone metastases are mainly located in the lumbar and lower thoracic regions. In long bones, metastases are almost always found in the metaphyseal and diaphyseal regions. Bone metastases are either osteolytic or osteoblastic. There are numerous exceptions: bone metastases can effect the whole skeleton due to the extensive distribution of haematopoietic bonemarrow in children. Distal bone metastases commonly occur during cases of metastatic disease, and lung cancer is most often the cause, with a net predominance of bone metastases in the hand. Bone metastases found exclusively in the cortical bone are rare. They are observed in the long bones of the lower limbs, in particular in the femur. In 50% of cases, they are as the result of lung cancer. Blowout or expansile bone metastases are common in thyroid and kidney cancers, and are often how the diseases are spotted. Finally, pseudosarcomatous bone metastasis that stimulate bone sarcoma due to the presence of an aggressive, spiking, periosteal reaction forming a large mass of soft tissue, are usually observed in prostate cancer. MRI and PET-scans are currently the preferred investigations performed to monitor bone metastases, enabling both a morphological and quantitative assessment to be made. For certain cancers, in particular prostate cancer, scintigraphy remains the investigation of choice. A CT scan will be requested to determine the extent of osteolysis and the risk of fracture, so that decisions regarding treatments can be made. X-rays will also be prescribed, focusing on areas of pain.