Introduction: Extra-skeletal Tc-99m MDP uptake is not uncommon. It could be a problematic when it mimics a metastatic osseous lesion. Due to lack of proper anatomical localization, Planar bone scintigraphy (PBS) alone can't resolve this problem. Adding single photon emission tomography / computed tomography (SPECT/CT) images increases the diagnostic accuracy of planar bone scintigraphy. SPECT/CT has great impact on patients' management by preventing misinterpretation through precise localization and proper characterization of these uncertain lesions. In this study, we compared the diagnostic accuracy of SPECT/CT versus PBS in characterization of extra-skeletal lesions detected on conventional PBS in known cancer patients. Materials and Methods: This is a retrospective study including 50 patients with known cancer referred for conventional (PBS) for metastatic work up. PBS was acquired followed by SPECT/CT images for the concerned area. Diagnostic performance indices from both modalities (PBS& SPECT/CT) were compared against the reference standard (clinical/imaging follow-up). Results: A total of 50 known cancer patients were included in this study (37 females, 13 males) with median age 64 years