There is a large variety of tumors and tumorlike lesions that can involve the skeleton. These tumors and tumorlike lesions present a bewildering spectrum of radiologic appearances that all too often can lead to misinterpretations resulting in suboptimal management of patients. Although primary malignancies are relatively rare, they often pose an intriguing diagnostic problem for radiologists, particularly as the pathology is frequently equally challenging.

Skeletal Bisphosphonates-(99mTc) SPECT/multislice CT is a useful problem solving tool that can be utilised selectively to assess the anatomical significance of equivocal areas of tracer uptake on planar whole-body scintigraphy or define the functional significance of indeterminate abnormalities detected on cross-sectional morphological imaging [1]. SPECT/CT is particularly useful for problem solving of indeterminate bone lesions (as opposed to joint lesions).

Likely, but still controversial, mechanisms of uptake of bisphosphonates-(99mTc) are multiple: uptake on organic phase, uptake on mineral phase and/or cellular internalization (osteoclasts and osteoblasts). These tissular- and cellular-levels mechanisms have been lumped together and oversimplified by increased bone vascularization and increased bone turnover.

Bisphosphonates-(99mTc) SPECT/CT and Fluoride-(18F) PET/CT are analysed according a common pathway, because of the similarities of normal and abnormal distribution of these two bone-seekers radiopharmaceuticals of these two cross-sectional hybrid imaging modalities.

Bone tumors and pseudotumors complete phenotyping must incorporate radiological and scintigraphic features.