Article Sections

Introduction

Osteosarcoma is derived from osteoid-forming mesenchymal cells and is the most common primary malignant bone tumor in children and young adults.  This aggressive tumor typically occurs in the metaphysis of long bones (eg, distal femur, proximal tibia) ( Figure 1).

Pathogenesis

Osteosarcoma is thought to arise in mesenchymal stem cells or osteoblastic progenitor cells due to a multifactorial involvement of tumor suppressor gene deregulation, oncogene activation, and a lack of DNA repair mechanisms.  This malignant transformation occurs mostly during the rapid growth phase of long bones (ie, adolescence) but can also be due to hereditary genetic mutations (eg, RB1, TP53).  As a result, the affected bone loses its normal trabecular pattern, and disorganized osteoid matrix is deposited by malignant cells.

Risk factors

Risk factors for the development of osteosarcoma include the following:

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