Abstract:
Objective To explore the clinical features and comprehensive imaging findings of phosphaturic mesenchymal tumor (PMT).
Methods A total of 38 histopathologically proven patients with PMT (22 males and 16 females; age, 8–72 years; median age, 45.5 years) in the Sixth People's Hospital Affiliated to Shanghai Jiaotong University from March 2014 to November 2018 were included in this study. The relevant clinical data and ultrasound, CT, MRI, 99Tcm-hydrazinonicotinamide-Tyr3-octreotide (99Tcm-HYNIC-TOC) SPECT/CT, 99Tcm-methylenediphosphonate (99Tcm-MDP) SPECT/CT bone scan, and 18F-fluorodeoxyglucose (FDG) PET/CT imaging findings were retrospectively analyzed, and their comprehensive imaging findings and clinical features were summarized.
Results The clinical manifestations of patients with PMT were mainly progressive systemic bone pain, muscle weakness, and local discomfort at the primary site of the tumor. All patients showed hypophosphatemia before operation. Of the 38 patients included, 8, 20, 18, 12, 8, and 7 patients respectively received ultrasound, CT, MRI, 99Tcm-HYNIC-TOC SPECT/CT, 99Tcm-MDP SPECT/CT bone scan, and 18F-FDG PET/CT. The ultrasonographic characteristics were low or mixed echoes and abundant color blood flow signals. Also, 50.0% (4/8) of the osseous PMT were osteolytic on CT, 12 soft tissue lesions were abnormal density focus or soft tissue mass on CT. All lesions presented low signal intensity on T1 weighted imaging and high or low signal intensity on T2 weighted imaging in 18 patients who underwent MRI, and tumor parenchyma was obviously enhanced. Ten of the 12 (83.3%) patients were positive on 99Tcm-HYNIC-TOC SPECT/CT imaging. 99Tcm-MDP SPECT/CT bone scan showed increased radiotracer uptake over the bone lesions, and one case of soft tissue lesion showed a slight increase in radiation uptake. On 18F-FDG PET/CT, all lesions showed intense FDG uptake with a median maximum standardized uptake value of 4.0 (range, 3.1–10.7).
Conclusions The clinical feature of PMT is tumor-induced osteomalacia with hypophosphatemia. However, the symptoms of the primary tumor are not prominent. No specific imaging findings of PMT were noted. However, 99Tcm-HYNIC-TOC SPECT/CT, 99Tcm-MDP SPECT/CT bone scan, and 18F-FDG PET/CT may be helpful in tumor localization and whole-body assessment.