PMC7771493_01
Axial, coronal, and sagittal views of gadolinium-enhanced T1-weighted MRI of a patient with giant cell tumor of sphenoid bone at preoperative (a), postoperative (b), 3 months after the operation (c), and 3 months after the initiation of denosumab treatment (d).
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F1
CT and magnetic resonance imaging (MRI) showed a well-enhanced mass lesion in the sphenoid sinus, with osteolytic invasion of ethmoid cells anteriorly, the sellar floor, dorsum sellae, and posterior clinoid processes posteriorly, and the clivus inferiorly [Figure 1]. However, denosumab therapy was initiated 3 months after the operation, because rapid regrowth of residual tumor was confirmed on MRI [Figure 1c]. Thereafter, tumor reduction and bone formation were induced [Figure 1d] and sustained for 5 years.
Photomicrograph of hematoxylin and eosin (H and E)-stained histopathologic specimens from a patient with a giant cell tumor of sphenoid bone, demonstrating numerous multinucleated osteoclast-like giant cells distributed diffusely among a background of neoplastic mononuclear stromal cells and mononuclear macrophage linage cells.
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F2
Pathological diagnosis was confirmed as giant cell tumor [Figure 2].
CT scans at preoperative (a), 2 years after the initiation of the denosumab treatment (b), a year after extending the dosing interval of denosumab to 4 monthly (c), and a year (d) and 2 years (e) after extending the dosing interval of denosumab to 6 monthly.
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F3
Subtle changes of an ossified lesion under denosumab treatment could be clearly detected on CT images [Figure 3]. Denosumab treatment consisted of 120 mg subcutaneous injections every 28 days for the first 2 years, with additional doses on days 8 and 15 [Figure 3b]. Subsequently, the dosing interval was gradually prolonged to avoid the occurrence of side effects, with 4 monthly dosing for the next 1 year [Figure 3c], followed by a 6 monthly dosing for 2 years [Figure 3d and e]. With the extension of the dosing interval, there has been slight growth of ossified tumor, but it could be controlled to be within an acceptable range [Figure 3b-d]. Because the lesion has remained unchanged over the 1 year treatment by a 6 monthly dosing [Figure 3e], the treatment continues to be maintained at this dosing interval.