High grade surface osteosarcoma
High grade surface osteosarcoma is a rare, usually aggressive osteosarcoma
arising from the surface of the bone. Most commonly affected site is the femur, followed by humerus and tibia. The tumour presents as a partially mineralised surface mass extending into the soft tissues. The underlying cortex is generally partially destroyed, and periosteal new bone is commonly present at the periphery of the tumour. Tumours vary in consistency depending upon whether they are predominantly osteoblastic, chondroblastic, or fibroblastic. However, all tumours invariably have "soft" areas in them, a feature which helps to separate them from parosteal osteosarcomas
. Additional distinguishing characteristics are high grade cytological atypia and lace-like osteoid as seen in conventional osteosarcoma, and the absence of low grade tumour regions.
High grade surface osteosarcoma has a peak incidence in the second decade of life, with a slight predilection for males. Individual response to chemotherapy is a major prognostic factor
Fletcher CDM, Unni KK, Mertens F (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of Soft Tissue and Bone.
IARC Press: Lyon 2002