The Importance Of Pathological Examination In The Treatment Approach Of Osteosarcoma Cases

Osteosarcoma is the most common primary malignant bone tumour in children and adolescents.  A malignant tumor in which the cells synthesize bone.

Most cases occur in children (10 – 14 years old) and are primary; secondary osteosarcoma is most common in adults. Osteosarcoma may arise in any bone but especially, long bones of extremities (near the most proliferative growth plates). Multifocal osteosarcoma may occur in the setting of Paget disease of the bone. Clinically, painful enlarging mass lesion is common and may be seen pathologic fracture in a minority of cases (5 – 10%)

For diagnosis of  osteosarcoma, radiology and pathology common evalutaion is very important. Especially, for prognosis, tumorous bone tissue have to examine macroscopically and microscopically.  There are many types of osteosarcoma that differ based on the tumor’s location (within the bone or on the surface of the bone) and the grade of the tumor (low grade, intermediate grade or high grade). > 90% of osteosarcoma is conventional (high grade, intramedullary) osteosarcoma.

More importantly, the role of pathological examination is very important in the treatment approach to osteosarcoma cases. A minor subset of low-grade osteosarcoma can be cured by surgery alone. Chemotherapy is started before surgery in high-grade osteosarcomas. After chemotherapy, the tumorous bone tissue is surgically removed. The removed part is examined first macroscopically and then microscopically by the pathology.

Surgical margins are checked microscopically and it is checked whether there is any remaining tumor. After the treatment in the tumor area, the rate of necrosis (dead tissue) is checked. Histologic response to neoadjuvant chemotherapy is one of the most important prognosticators of survival. Histomorphologically, determine of >90% necrosis indicates a successful response to treatment. Therefore, both macroscopic and microscopic tissue examination is very important in terms of evaluating the response to treatment.

Surgical Pathologist, Istanbul/ Turkey