Sarcoma in the bone consists several diagnostic entities. The most common are:
- Osteosarcoma - malignant tumor with bone differentiation
- Ewing's sarcoma/PNET - originate from neuroectodermal-derived cells
- Chondrosarcoma - malignant tumor with cartilage differentiation
Other rare bone sarcomas are chordoma, malignant fibrous histocytomas (MFH) in the bone, fibrosarcoma, angiosarcoma, leiomyosarcoma, malignant giant cell tumor, and adamantinoma.
In approximately 70% of cases, osteosarcoma occurs eccentric to the metaphyseal region in long bones, most often, at the knee joints and at the proximal end of the humerus. Ewing's sarcoma occurs everywhere in the body but is more common in the diaphyseal or metaphyseal regions of long bones, especially the lower extremities as well as the pelvis. In 90% of the cases, chondrosarcoma is localized to the marrow (central) or on the surface (peripheral).
The incidence of all bone sarcoma was 41 new cases in Norway in 2012. There where 30 men and 11 women (6).
Osteosarcoma occurs most frequently. There are 10-15 new cases each year. The disease is most common in younger ages (10-30 years) and the average age at diagnosis is about 16 years. Osteosarcoma occurs more often in boys than girls (2:1).
Ewing's sarcoma constitutes 5-10 new cases each year. The median age is 14 years and the disease is very rare above 40 years. There is an equal distribution between men and women.
The median age at the time of diagnosis of chondrosarcoma is 50 years. The disease occurs more frequently in men than women (1.5:1).