Metastatic osteosarcoma of the liver. Light micrograph from affected tissue. Metastatic osteosarcoma (pink) most commonly affects the lungs and other bones. Hepatic metastasis is extremely rare. Osteosarcoma is a cancerous tumor in a bone. Specifically, it is an aggressive malignant neoplasm that arises from primitive transformed cells of mesenchymal origin. Osteosarcoma is the most common histological form of primary bone cancer. It is most prevalent in children and young adults. If the osteosarcoma has already spread when it is first found, the 5-year survival rate is about 15% to 30%. Magnification: x150 when printed at 10 centimetres across. Human tissue