Hip potpourri: Unravelling the bone tumors around hip joint

A variety of malignant and benign bone tumors arise from the pelvis and proximal femur; bones around the hip joint, and this area poses a unique challenge both for the radiologists and the surgeons/radiation oncologists. The accuracy of characterizing and diagnosing bone tumors of the appendicular skeleton, such as proximal femur, on radiographs, is excellent for experienced musculoskeletal onco-radiologists. However, when it comes to pelvic bones, accurately detecting a lesion on a radiograph itself becomes a challenge many-a-times, due to complex anatomy and overlying bowel gas shadows, and in such cases, we have to rely on cross-sectional imaging, particularly magnetic resonance imaging (MRI), for further evaluation. In addition to solving dilemmas regarding tumor characterization, MRI plays a pertinent role in providing the local staging for malignant bone tumors; essential for chalking out treatment plan, in post-treatment assessment; to deciding upon further management, and demonstrating enhancing nidus of osteoid osteoma using dynamic post-contrast images. Computed tomography may be required sometimes to provide information on the bone tumor matrix, for example, confirm the presence of osteoid matrix in osteosarcoma, and the presence of cortical breach, particularly in tumors of pelvic bones, as radiographs are of limited value here. In this review, we have provided a systematic approach to characterize a bone tumor on a radiograph using a checklist, we have provided the MRI protocol that is followed in our institute while evaluating these tumors, and at the end, we have discussed a few malignant and benign bone tumors.