Seminars in bone pathology. Conventional osteosarcoma. Present advances. What is new and what is old?

Osteosarcoma (OS) is the most common primary malignant bone tumor of connective tissue origin it affects teenagers in a very aggressive way. It causes significant harm with poor prognosis, and it is very difficult to cure. during the past two decades, the emergence of neoadjuvant chemotherapy of osteosarcoma has greatly improved the survival rate of osteosarcoma patients (5 year survival 60–70%). nearly half of these patients are not sensitive to chemotherapy drugs and die due to lung metastasis within 2 to 3 years.
The majority of patients (80%) have small tumor foci transferred into their systemic blood before treatment; the importance of improving long-term survival in patients by controlling lung metastases through effective drug and gene regulation has been increasingly recognized. the invasive ability of tumor cells is one of the important factors in their capacity to metastasize to distant locations in the body. Production of woven bone by tumor cells defines the neoplasm, however, variable amounts of cartilage and fibrous tissue matrix are often encountered as accompanying components. Osteoblastic, chondroblastic and fibroblastic types comprise the 3 major cell types of OS, but the percentage of cell type and matrix will vary in any individual case. The role of the pathologist is becoming more important because of the modern genetic and molecular and IHC markers in diagnostic procedures, the pathologists must rise to the occasion.