Last edited 05/2019
Osteoclastoma is a tumour of uncertain origin, composed of osteoclast-like cells, usually benign at their outset.
Osteoclastomas account for about 5% of primary bone tumours with their highest incidence in the 20 to 40 year age group. There is a slightly biased sex incidence, with males more commonly affected than females.
They commonly occur at the end of long bones - for example the lower end of the femur, the upper end of the humerus.
About 33% of these tumours remain truly benign, about 33% of them become locally invasive, and the remaining 33% metastasise.