Our case is a 68-year-old female with a past medical history of hyperlipidemia and insulin-controlled type 2 diabetes mellitus who presented with right knee pain and swelling. She denied any history of trauma. Radiograph and magnetic resonance imaging were concerning for GCTB. She underwent curettage and cementation of the right distal femur lesion and histological examination confirmed the suspected diagnosis of GCTB. Approximately one year later, she developed local recurrence of the tumor, which was also curetted with additional use of cement. One year after the second surgery, a routine chest radiograph showed lung lesions suspicious of metastatic disease (Figure 1). At the time she was feeling well, with only mild pain in her right knee. Computed tomography (CT) imaging verified the presence of several pulmonary nodules including a large right lower lobe (RLL) mass measuring 5.6 cm (Figure 2). CT-guided core needle biopsy of the largest lung mass confirmed metastatic GCTB (Figure 3).
After discussion at a tertiary center musculoskeletal tumor board the patient was started on denosumab therapy. Treatment was initiated with a loading dose of 120 mg every week for three weeks. She was then transitioned to receive a dose of 120 mg every four weeks. She was also placed on daily calcium and vitamin D supplements.
At 3 months after the initiation of treatment she had repeat CT imaging of her chest. The scan showed the RLL mass had decreased considerably in size, now measuring 2.6 cm in its greatest dimension. There was also a decrease in size of the other pulmonary lesions (Figure 2). No new pulmonary nodules were seen. Since then she has had CT imaging of her chest every three months and radiographs of her right knee every six months. She has been without subjective complaint at each follow-up visit. After 16 months of denosumab therapy, q cardiothoracic surgery consultation was obtained and, due to the location and stability of disease, no surgery was recommended. The patient also was adamantly opposed to surgery. She continued to tolerate the denosumab without any evidence of side effects or complications.
Forty-eight months after initiating treatment, CT imaging showed the stable RLL mass as well as the smaller pulmonary lesions to be unchanged in size (Figure 2).