Overexpression of hexokinase-2 in giant cell tumor of bone is associated with false positive in bone tumor on FDG-PET/CT.

INTRODUCTION: The aim of the current study was to evaluate the usefulness of maximum standardized uptake value (SUV(max)) in 2-deoxy-2-F(18)-fluoro-D-glucose positron emission tomography combined with computed tomography (18F-FDG-PET/CT) for preoperative differential diagnosis between benign and malignant bone tumors.

MATERIALS AND METHODS: Seventy-nine patients with bone tumors were examined by FDG-PET prior to histopathological diagnosis. The SUV(max) was calculated and compared between benign and malignant lesions, and among different histopathological subgroups, to identify false-positive histological subtypes.

RESULTS: There was a statistically significant difference in the SUV(max) of benign (3.7 ± 3.3; n = 17) and malignant (5.3 ± 3.3; n = 62) bone tumors. However, receiver operating characteristic curve analysis revealed the poor accuracy of this distinction. The cut-off value was determined to be 2.6, while the value of sensitivity and specificity was calculated to be 74.2 and 64.7 %, respectively. Giant cell tumor of bone (9.0 ± 2.0; n = 5) displayed a higher SUV(max) than osteosarcoma (4.2 ± 2.3; n = 18). Immunohistochemical analysis demonstrated that markers of these cancers, hexokinase-2 (HK-2) and glucose transporter type 1 (GLUT-1), supported our findings.

CONCLUSION: The poor accuracy of SUV(max) in 18F-FDG-PET/CT in distinguishing malignant from benign bone tumors was confirmed; some benign bone tumors showed high FDG uptake. Giant cell tumor of bone was a major false-positive histopathological subtype of bone tumors, showing high FDG accumulation. HK-2 contributed significantly to FDG uptake, whereas GLUT-1 appeared to play no role in FDG uptake in giant cell tumor of bone.