Clinical and imaging characteristics of phosphaturic mesenchymal tumors: a case series analysis.

OBJECTIVE

To characterize the clinical, biochemical, pathological, and multimodal imaging features of phosphaturic mesenchymal tumors (PMTs).

METHODS

We retrospectively reviewed 10 patients with pathologically confirmed PMT. Clinical presentation, laboratory findings, histopathologic and immunohistochemical features, and imaging manifestations across multiple modalities were systematically analyzed.

RESULTS

All patients presented with long-standing fatigue and bone pain. Preoperative laboratory tests revealed varying degrees of hypophosphatemia and elevated alkaline phosphatase, while postoperative serum phosphate levels gradually normalized. Histopathology demonstrated heterogeneous morphologies. Immunohistochemistry showed consistent SATB2 and SSTR2 positivity in tested cases, whereas the Ki-67 proliferation index ranged from 1% to 15%. On CT, primary lesions appeared as soft-tissue density masses or ground-glass-like nodules, often with irregular calcification and focal bone destruction. MRI demonstrated hypointensity on T1-weighted images, hyperintensity on T2-weighted images, and moderate to marked heterogeneous enhancement. Both [18F]F-OC PET/CT and [18F]F-FDG PET/CT revealed variable degrees of radiotracer uptake in all lesions.

CONCLUSION

PMTs are characterized by typical TIO-related clinical and biochemical abnormalities, and SATB2 and SSTR2 are highly sensitive immunohistochemical markers for definitive diagnosis. Whole-body [18F]F-OC PET/CT, targeting somatostatin receptors, serves as a highly specific first-line modality for tumor localization. Dedicated CT and MRI provide essential anatomic characterization for surgical planning, while [18F]F-FDG PET/CT offers complementary, non-tumor-specific metabolic information. [99mTc]Tc-MDP planar bone scintigraphy is useful for assessing the systemic skeletal burden of osteomalacia. This stepwise, multimodal approach improves diagnostic accuracy and supports timely surgical management.