Giant Cell Tumor of Bone Without Giant Cells with a Long Clinical Course: A Case Report.

Giant cell tumor of bone (GCTB) consists of a mixture of neoplastic mononuclear cells and non-neoplastic cells, including polynuclear giant cells. Recently, with the spread of the immunohistochemical staining marker H3.3 G34W corresponding to specific genetic abnormalities, the histological diversity of GCTB has been recognized. GCTB without giant cells is uncommon, although it has also been reported previously. Herein, we describe a 45-year-old man with GCTB without giant cells who was successfully diagnosed using H3.3 G34W immunohistochemistry. Other unusual findings in GCTB that were identified in this patient include bone and osteoid formation with a long clinical course of 13 years. We also compared the histological findings of the current patient to those who received denosumab therapy.