UNASSIGNED: Both bone metastases and multiple myeloma (MM) are malignant diseases that can appear osteolytic on imaging and are difficult to differentiate. While positron emission tomography/computed tomography (PET/CT) has been demonstrated useful for the diagnosis of various bone lesions, correlations between PET/CT and histopathology and these diseases are unclear. This retrospective study investigated the optimal cutoff standardized uptake value (SUV) to differentiate MM and bone metastasis.
UNASSIGNED: Patients with newly diagnosed osteolytic lesions (n = 344) and suspected malignancy underwent both fluorodeoxyglucose (FDG) PET/CT and biopsy/surgery. FDG uptake and morphologic changes (e.g., soft tissue mass formation) were compared with pathological results.
UNASSIGNED: A total of 8896 osteolytic lesions were evaluated. The SUVmax of MM osteolytic lesions (1.6 ± 0.7) was significantly lower than that of bone metastases (5.5 ± 2.7; p = 0.000). The best cutoff SUVmax for differentiating MM and bone metastasis was 2.65 (sensitivity 86.1%, specificity 94.7%; p = 0.000). The SUVmax of bone lesions of soft tissue mass was higher than that for pure osteolytic lesions (p = 0.000). A greater percentage of patients with bone metastasis had a soft tissue mass (7%) than did patients with MM (2%). The mean SUVmax of bone metastases was 5.5 ± 2.7 (0.4-30.4); that of primary tumors was 7.5 ± 4.2 (1.0-28.5). The SUVmax of bone metastases significantly correlated with the SUVmax of primary tumors (r = 0.532; p = 0.000).
UNASSIGNED: FDG PET/CT is a valuable tool to differentiate osteolytic lesions. The best cutoff value of SUVmax for differentiating MM from bone metastasis is 2.65. The significant correlation between the SUVmax of bone metastasis and that of primary tumors is helpful for detecting primary tumors.

Over the past few decades, there has been growing interest in understanding the molecular mechanisms of cancer pathogenesis and progression, as it is still associated with high morbidity and mortality. Current management of large bone sarcomas typically includes the complex therapeutic approach of limb salvage or sacrifice combined with pre- and postoperative multidrug chemotherapy and/or radiotherapy, and is still associated with high recurrence rates. The development of cellular strategies against specific characteristics of tumour cells appears to be promising, as they can target cancer cells selectively. Recently, Mesenchymal Stromal Cells (MSCs) have been the subject of significant research in orthopaedic clinical practice through their use in regenerative medicine. Further research has been directed at the use of MSCs for more personalized bone sarcoma treatments, taking advantage of their wide range of potential biological functions, which can be augmented by using tissue engineering approaches to promote healing of large defects. In this review, we explore the use of MSCs in bone sarcoma treatment, by analyzing MSCs and tumour cell interactions, transduction of MSCs to target sarcoma, and their clinical applications on humans concerning bone regeneration after bone sarcoma extraction.