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==Introduction==

==Introduction==

Haemangiopericytomas are '''very common mesenchymal tumours''' in '''middle-aged or older dogs'''. It is more common in '''large breed''' dogs but there is no sex predilection.

Haemangiopericytomas are '''very common mesenchymal tumours''' in '''middle-aged or older dogs'''. It is more common in '''large breed''' dogs but there is no sex predilection.

The '''origin of these tumours is uncertain''', although they seem to be associated with the periphery of blood vessels and they may be related to Peripheral Nerve Sheath Tumours.

The '''origin of these tumours is uncertain''', although they seem to be associated with the periphery of blood vessels and they may be related to Peripheral Nerve Sheath Tumours.

==Clinical signs==

==Clinical Signs==

Tumours are usually '''solitary''', arise in the subcutis '''around joints of limbs''', and are multilobulated and '''inflitrative'''.

Tumours are usually '''solitary''', arise in the subcutis '''around joints of limbs''', and are multilobulated and '''infiltrative'''.

Their gross appearance varies, from white/gray to red, and rubbery to fatty.

Their gross appearance varies, from white/gray to red, and rubbery to fatty.

==Diagnosis==

==Diagnosis==

'''Fine Needle Aspiration''' should be performed.

'''Fine needle aspiration''' (FNA) should be performed.

 

:Characteristic cytological features include: '''perivascular whorls of fusiform cells'''. Cells may also be arranged in interlacing bundles. In some tumours there is a patchy mucinous matrix.

Characteristic cytological features include: '''perivascular whorls of fusiform cells'''. Cells may also be arranged in interlacing bundles. In some tumours there is a patchy mucinous matrix.

The tumour may be well demarcated from adjacent structures, but it often '''invades along fascial planes''' leading to recurrences.

The tumour may be well demarcated from adjacent structures, but it often '''invades along fascial planes''' leading to recurrences.

Freeman, K. (2007) '''Self-assessment colour review of: Veterinary cytology''' ''Manson Publishing''

Freeman, K. (2007) '''Self-assessment colour review of: Veterinary cytology''' ''Manson Publishing''

[[Category:To Do - Helen]]

 

[[Category:To Do - Review]]

 

 

[[Category:Neoplasia]]

[[Category:Expert Review - Small Animal]]