Successful treatment with denosumab of a giant cell tumor of bone in the iliac bone of an 84-year-old man

Abstract

We report a case of GCTB in an 84-year-old Japanese man who had a tumor in his left iliac bone and was treated safely with denosumab. The patient noticed a painful mass, with gradual enlargement, in his left low back next to the iliac region. Magnetic resonance imag-ing revealed that the tumor measured 94 × 66 × 90 mm and was located in the left iliac bone. Histologically, the tumor was composed of proliferative oval-shaped mononuclear cells, admixed with large number of osteoclast-like giant cells. Immunohistochemically, a strong positivity for histone 3.3 G34W mutant protein was observed in the nuclei of the mononuclear cells, confirming the diagnosis of GCTB. Because it was con-sidered as unresectable tumor, the patient was treated with denosumab without any side effects.