Changes

==Introduction==

==Introduction==

This is well-established in humans but '''rare in animals''', with only a few individual cases in '''dogs and cats'''.

This is well-established in humans but '''rare in animals''', with only a few individual cases in '''dogs and cats'''.

Species, age or breeds specificities have not been established.  

Species, age or breeds specificities have not been established.  

The histogenesis of the tumour is uncertain. The multi-nucleated giant cells which are the hallmark of this disease arise by '''fusion of proliferating, plump, ovoid to spindle-shaped neoplastic cells''' comprising the bulk of the tumour mass. These cells have the same enzymatic behaviour as osteoclasts, and the tumours are sometimes called '''osteoclastomas'''.

The histogenesis of the tumour is uncertain. The multi-nucleated giant cells which are the hallmark of this disease arise by '''fusion of proliferating, plump, ovoid to spindle-shaped neoplastic cells''' comprising the bulk of the tumour mass. These cells have the same enzymatic behaviour as [[osteoclasts]], and the tumours are sometimes called '''osteoclastomas'''.

'''Benign and malignant''' variations of the tumour exist, although the benign form is thought to be more common.

'''Benign and malignant''' variations of the tumour exist, although the benign form is thought to be more common.

==Clinical signs==

==Clinical Signs==

This tumour arises as a '''painful swelling on the limb'''. '''Vertebral, costal and metacarpal''' lesions can also exist.

This tumour arises as a '''painful swelling on the limb'''. '''Vertebral, costal and metacarpal''' lesions can also exist.

'''Biopsy''' yields a population of large numbers of multinucleated giant cells that '''ressemble osteoclasts'''. Their cytoplasmic borders are often indistinct. The tumour is '''highly vascular''' and may contain cavernous spaces and areas of haemorrhage. '''Osteoid production is absent or minimal'''.

'''Biopsy''' yields a population of large numbers of multinucleated giant cells that '''ressemble osteoclasts'''. Their cytoplasmic borders are often indistinct. The tumour is '''highly vascular''' and may contain cavernous spaces and areas of haemorrhage. '''Osteoid production is absent or minimal'''.

Confusion may arise as '''osteosarcomas''' may contain large numbers of giant cells and closely ressemble giant cell tumours.

Confusion may arise as [[Osteosarcoma|'''osteosarcomas''']] may contain large numbers of giant cells and closely resemble giant cell tumours.

'''Cytological exam''' will reveal: a '''high percentage of multinucleated cells''' among many plump, spindle-shaped or ovoid mesenchymal cells.

'''Cytological exam''' will reveal: a '''high percentage of multinucleated cells''' among many plump, spindle-shaped or ovoid mesenchymal cells.

Moulton, J. (1978) '''Tumours in domestic animals''' ''University of California Press''

Moulton, J. (1978) '''Tumours in domestic animals''' ''University of California Press''

[[Category:To Do - Helen]]

 

[[Category:To Do - Review]]

[[Category:Bones - Neoplastic Pathology]]

[[Category:Expert Review - Small Animal]]

[[Category:Neoplasia]]