Denosumab in patients with aneurysmal bone cysts: A case series with preliminary results

Aneurysmal bone cyst (ABC) is a rare skeletal tumor usually treated with surgery/embolization. We hypothesized that owing to similarities with giant cell tumor of bone (GCTB), denosumab was active also in ABC.

In this observational study, a retrospective analysis of ABC patients treated with denosumab was performed. Patients underwent radiologic disease assessment every 3 months. Symptoms and adverse events were noted.

Nine patients were identified (6 male, 3 female), with a median age of 17 years (range 14-42 years). Primary sites were 6 spine-pelvis, 1 ulna, 1 tibia, and 1 humerus. Patients were followed for a median time of 23 months (range 3-55 months). Patients received a median of 8 denosumab administrations (range 3-61). All symptomatic patients had pain relief and 1 had paresthesia improvement. Signs of denosumab activity were observed after 3 to 6 months of administration: bone formation by computed tomography scan was demonstrated in all patients and magnetic resonance imaging gadolinium contrast media decrease was observed in 7/9 patients. Adverse events were negligible. At last follow-up, all patients were progression-free: 5 still on denosumab treatment, 2 off denosumab were disease-free 11 and 17 months after surgery, and the last 2 patients reported no progression 12 and 24 months after denosumab interruption and no surgery.

Denosumab has substantial activity in ABCs, with favorable toxicity profile. We strongly support the use of surgery and/or embolization for the treatment of ABC, but denosumab could have a role as a therapeutic option in patients with uncontrollable, locally destructive, or recurrent disease.