Introduction

The vast majority of malignant bone lesions initiate as bone marrow deposits of malignant cells. As the lesion enlarges, the surrounding bone undergoes osteoclastic (resorptive) and osteoblastic (depositional) activity. Based on the balance between these two processes, lesions may appear radiographically, as lytic, sclerotic (blastic), or mixed (1–3).

Osteosarcoma is the most frequent primary bone malignancy in children and second in adults following multiple myeloma. The Ewing sarcoma family of tumors is the second most frequent primary bone malignancy in children and young adults (4). Bone metastases are the most common malignant bone tumor, with breast cancer being the leading primary tumor in women and prostate cancer in men, followed by lung cancer. The type of metastases and the incidence of metastatic skeletal spread depend on the type of malignancy and the disease stage, respectively (5).

The purpose of imaging is to identify malignant skeletal involvement as early as possible, to determine the extent of the disease, to evaluate the presence of clinically relevant complications (such as fractures or lesions which harbor risk for neurologic deficit), to monitor response to therapy, and at times, to guide biopsy (5, 6).