ESPE Abstracts

Background: Giant cell granulomas (GCG) are uncommon bony lesions that most commonly affect the maxilla and mandible; whilst generally benign they can be disfiguring to the face. Historically, GCGs have been treated with steroids or bisphosphonates to try and avoid surgical resection. Over recent years denosumab, a human monoclonal antibody which acts against the receptor activator of nuclear factor kappa B ligand, has been shown to be effective in treating GCGs, although there are risks in using the drug in growing children. We present a case of a child treated with denosumab using quantification of Tc99m-MDP uptake on SPECT imaging to guide treatment.

Case presentation: An 11-year-old female presented with an oral lesion. CT scan and biopsy confirmed a diagnosis of GCG of the maxilla. Initial treatment with weekly steroid injections resulted in a short period of stability before growth progression returned. MRI/SPECT imaging showed an expansile, lytic left maxillary lesion with increased Tc99m-MDP uptake, measuring 36mm x 41mm x 42mm. Zoledronic acid was commenced, after which a small reduction in lesion size was noted, although MRI/SPECT imaging after a year of treatment showed no change with increased sclerosis and increased Tc99m-MDP uptake. Denosumab was commenced at 60mg every 4 weeks (increased to 120mg after 11 months) by subcutaneous injection with calcium and vitamin D supplementation. The patient had close monitoring of biochemistry and bone turnover markers, bone densitometry, plain radiographs and dental reviews. After 14 months of denosumab, the patient had suppressed bone formation markers, MRI scan showed lesion size was unchanged but with increased sclerosis. However, semi-quantitative analysis showed a reduction in the ratio of Tc99m-MDP uptake in the lesion, compared to normal bone, from 4.9 to 1.4. The lesion has clinically reduced after 19 months of denosumab with only mild facial asymmetry. Denosumab weaning has begun with the aim of stopping treatment in the next 6 months. Regular imaging with semi-quantitative analysis of uptake will continue to guide future treatment.

Conclusion: This case report adds further support for the use of denosumab in the treatment of GCG in paediatric patients. Imaging using SPECT with semi-quantitative analysis of Tc99m-MDP uptake allowed for valuable assessment of denosumab effect which was difficult to appreciate on standard MRI/SPECT images.