Page 863 - Textbook of Pathology, 6th Edition

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Figure 28.17 Giant cell tumour (osteoclastoma). The end of the
long bone is expanded in the region of epiphysis. Sectioned surface
shows circumscribed, dark tan, haemorrhagic and necrotic tumour.

Stromal cells are mononuclear cells and are the real CELL OF ORIGIN. Though designated as giant cell tumour CHAPTER 28
tumour cells and their histologic appearance determines or osteoclastoma, the true tumour cells are round to spindled
the biologic behaviour of the tumour. Typically, they are mononuclear cells and not osteoclast-like giant cells.
uniform, plump, spindle-shaped or round to oval cells Histogenesis of tumour cells is uncertain but possibly they
with numerous mitotic figures. are of mesenchymal origin. Available evidence suggests that
Other features of the stroma include its scanty collagen osteoclasts are derived from fusion of circulating monocytes,
content, rich vascularity, areas of haemorrhages and the process being facilitated by transforming growth factor-
presence of macrophages. beta (TGF-β).
OTHER GIANT CELL LESIONS. This peculiar tumour with
Giant cell tumour of bone has certain peculiarities which above description is named ‘giant cell tumour’ but giant cells
deserve further elaboration. These are: its cell of origin, its are present in several other benign tumours and tumour-
differentiation from other giant cell lesions and its biologic like lesions from which the giant cell tumour is to be
behaviour. The Musculoskeletal System
distinguished. These benign giant cell lesions are:

Figure 28.18 Osteoclastoma. Microscopy reveals osteoclast-like multinucleate giant cells which are regularly distributed among the mononuclear
stromal cells.