MRI assessment of the bone adjacent to giant cell tumours and its association with local recurrence after intralesional curettage.

Aim: To assess the tumour border surrounding giant cell tumour of the bone (GCTB) using magnetic resonance imaging (MRI) and investigate its association with local recurrence.
Materials and Methods: Sixty-nine GCTBs in proximal tibiae and distal femurs were studied. The pathological basis of the paintbrush border sign was explored. Expression of Ki-67, matrix metalloproteinase-9 (MMP-9), vascular endothelial growth factor (VEGF), receptor activator of nuclear factor-κ B (RANK), and RANK ligand (RANKL) in GCTBs were investigated using immunohistochemistry. Patients treated with intralesional curettage were analysed retrospectively to investigate the prognostic role of the paintbrush border sign. The differences between rates were tested using the chi-square test or Fisher's exact test, as appropriate.
Results: The paintbrush border sign correlated well with infiltrative margins. The expression of MMP-9 was associated with the paintbrush border sign, and positively correlated with RANKL and VEGF expression. GCTBs with the paintbrush border sign had a higher rate of local recurrence (76.19 versus 20.59%, p<0.05). The paintbrush border sign was more common in proximal tibiae, and positively correlated with cystic change. The paintbrush border signs were detected at T1-weighted imaging, but the sign was only evident in four cases on T2-weighted imaging.
Conclusion: Pathologically, the paintbrush border sign correlates well with invasion of the bone around GCTB. MMP-9 might play a key role in the formation of penetrating irregular margins. The paintbrush border sign is revealed as a risk factor for local recurrence of GCTB. Sagittal T1-weighted imaging is crucial to diagnose the paintbrush border sign.
(Copyright © 2018. Published by Elsevier Ltd.)