Imaging of Malignant Skeletal Tumors

Malignant tumors of the skeleton represent a diverse group of primary and secondary neoplasms, each with unique imaging and clinical features. The radiologist encountering a lesion of the skeleton must apply a methodical approach to the analysis of imaging features to distinguish benign from malignant entities. This methodical approach can provide invaluable insight into the nature of the lesion, and will ultimately guide the final diagnosis; indeed, concordance between the imaging appearance and a preliminary histologic diagnosis is absolutely necessary to ensure that each lesion is appropriately diagnosed and managed. For the clinician, there is an ever-expanding array of potential imaging modalities that can characterize a lesion and evaluate its extent. Imaging will guide treatment, monitor response to therapy and facilitate discussions of prognosis. The purpose of this chapter is to familiarize the practicing clinician and radiologist with the most common malignant lesions of the skeleton. The chapter describes the major primary lesions of bone (osteosarcoma, chondrosarcoma, myeloma, Ewing’s Sarcoma and primary lymphoma of bone), as well as metastasis. Our goal is to familiarize the reader with the key imaging characteristics of each lesion, as well as the clinical features that may guide the differential diagnosis. The discussion incorporates all imaging modalities, including radiographs, magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography (PET) and bone scintigraphy, with a particular focus on the appropriate use of each modality in the diagnosis and staging of a newly detected lesion. Recent evidence, particularly focused on the newer modalities (MRI and PET), is presented to provide an evidence-based foundation for the imaging work-up.