Giant Cell Tumor of Bone in Patients 55 Years and Older: A Study of 34 Patients.

OBJECTIVES: Most giant cell tumors of bone (GCTs) occur in patients aged 20 to 40 years. We analyzed features of GCT in patients 55 years or older. METHODS: GCTs were examined for fibrosis, matrix, cystic change, histiocytes, mitoses, and necrosis. Clinical/radiologic data were collected. RESULTS: Thirty-four (5%) of 710 GCTs occurred in patients older than 55 years (14/20 male/female; 56-83 years) in long bones (n = 24), vertebrae (n = 6), pelvis (n = 3), and metacarpal (n = 1). Imaging was classic in 26 of 27 cases; one case appeared malignant. Morphologic patterns included fibrosis (n = 29), bone formation (n = 19), cystic change (n = 8), necrosis (n = 8), foamy histiocytes (n = 7), and secondary aneurysmal bone cyst formation (n = 1). Mitoses ranged from 0 to 18 per 10 high-power fields. Six recurred; one patient developed metastasis. Four of five cases harbored H3F3A mutations. CONCLUSIONS: GCTs in patients 55 years or older share pathologic characteristics with those arising in younger adults. Fibrosis and reactive bone are common, potentially leading to diagnostic confusion in this population. No histologic features correlate with adverse outcome.