الفهرس 
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Abstract
Osteosarcoma is a primary malignant tumor of the skeleton characterized by the
direct formation of immature bone or osteoid tissue by the tumor cells. Onset can occur
at any age; however, primary high grade osteosarcoma occurs most commonly in the
second decade of life. Parosteal osteosarcoma has a peak incidence in the third and
forth decade of life and secondary osteosarcoma are more common in older individuals.
(3) The lung is the most common metastatic site, followed by bone. (11)
The World Health Organization’s histological classification of bone tumors
separates the osteosarcomas into: central (medullary) and surface (peripheral) tumors
and recognizes a number of subtypes within each group. (17)
It most commonly occurs in the long bones of the extremities near metaphyseal
growth plates. The most common sites are:
- femur (42%, with 75% oftumors in the distal femur),
- tibia (19%, with 80% oftumors in the proximal tibia), and
- humerus (lO%, with 90% oftumors in the proximal humerus).
Other significant locations are the skull or jaw (8%) and pelvis (8%).
Most patients who present with OS of the appendicular skeleton complain of pain prior
to soft tissue swelling. The overlying skin feels warm and has prominent superficial
vasculature. Swelling is often accompanied by some limitation of motion .A painful
limp that increases with weight bearing is the third most common symptom. Systemic
symptoms, such as fever and night sweats, are rare. (78)
Since the early 1970s, substantial progress in dealing with musculoskeletal tumours
has been made, with improvements in surgical skills, radiology, chemotherapy,
pathology, and radiotherapy. Nowadays, 70-80% of all malignant tumours are treated
by limb salvage, without compromising the oncological result.
With the present protocols of neoadjuvant chemotherapy (4-6 cycles with the four most
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