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Also known as: '''''Mastocytosis'''''
==Introduction==
==Introduction==
Mast cells are a cell population that '''originate in the bone marrow''' and mature in connective tissue.
[[Mast Cells|Mast cells]] are a cell population that '''originate in the bone marrow''' and mature in connective tissue.
Mast cell tumours are '''ubiquitous''' in domestic animal species. The tumours can be '''focal or multicentric in the skin''' and may occasionally involve '''internal viscera such as the spleen, liver and intestine'''.
Mast cell tumours are '''ubiquitous''' in domestic animal species. The tumours can be '''focal or multicentric in the skin''' and may occasionally involve '''internal viscera such as the spleen, liver and intestine'''.
==Canine mast cell tumours==
==Canine mast cell tumours==
Mast cell tumours are the '''most common cutaneous tumour in the dog''', primarily a disease of older dogs. Boxers, Labrador retrievers, beagles and schnauzers have reported to be predisposed.
Mast cell tumours are the '''most common cutaneous tumour in the dog''', primarily a disease of older dogs. Boxers, Labrador Retrievers, Beagles and Schnauzers are reported to be predisposed.
'''Boxers are more predisposed''', but generally develop the low or intermediate grade forms of the disease which have a more favourable prognosis.
'''Boxers are more predisposed''', but generally develop the low or intermediate grade forms of the disease which have a more favourable prognosis.
Mast cell tumours '''vary widely in appearance'''.
Mast cell tumours '''vary widely in appearance'''.
The most common gross appearance is a '''small, raised, well circumscribed mass''' that may be hyperaemic, alopecic, ulcerated or look like normal skin.
The most common gross appearance is a '''small, raised, well circumscribed mass''' that may be hyperaemic, alopecic, ulcerated or look like normal skin. They may also appear as a '''poorly-defined, soft, fluctuant lesion'''. The tumours may become quite large, up to 30 cm, or may occur as a '''diffuse, inflamed, dermal thickening'''.
They may also appear as a '''poorly-defined, soft, fluctuant lesion'''.
They are more commonly found on the '''caudal half of the body'''.
They are more commonly found on the '''caudal half of the body'''.
'''Siamese cats''' are most are risk, and also develop a '''histiocytic variant''' of the disease.
'''Siamese cats''' are most are risk, and also develop a '''histiocytic variant''' of the disease.
Mast cell tumours occur in different forms in the cat. In one form, one or more tumours '''originate in the skin''' and may metastasise to regional nodes and other viscera. In the other, more common form, the neoplasm '''arises in internal organs''' without obvious cutaneous involvement. There is also a '''systemic''' and a '''leukaemic''' form.
===Clinical features===
===Clinical features===
Most mast cell tumours are '''benign''' and appear as well-differentiated dermal tumours.
Most mast cell tumours are of the 'mast cell form' and are similar to the cutaneous mast cell tumours of dogs. They usually appear on the head and neck of cats over the age of 4. Most are '''benign''' and appear as well-differentiated dermal tumours.
Cats that develop '''histiocytic variants''' are usually Siamese cats under the age of 4, but they can be of other breeds and older. Lesions are usually multiple, small subcutaneous papulonodules. The overall histological appearance is that of granulomatous inflammation with eosinophilic and lymphoid aggregates.
Special stains may be required to diagnose the uncommon variants of the disease.
Special stains may be required to diagnose the uncommon variants of the disease.
For the visceral and systemic form, signs will include: '''vomiting''', enlarged lymph nodes, depression, anorexia and possibly ascites.
===Treatment===
===Treatment===
Complete excision is curative, unless there are multiple tumours which may metastasise or recur.
Complete excision of the cutaneous mast cell tumours is curative, unless there are multiple tumours which may metastasise or recur.
For the histiocytic variant, the lesions often '''regress spontaneously''' and no treatment is usually necessary. The prognosis is good.
==Mast cell tumours in other species==
==Mast cell tumours in other species==
===Cattle===
===Cattle===
The majority of bovine mast cell tumours are '''malignant and have high metastatic potential'''.
The majority of bovine mast cell tumours are '''malignant and have high metastatic potential'''.
{{Learning
|Vetstream = [https://www.vetstream.com/canis/search?s=mastcell Mast cell tumour]
|flashcards = [[Small Animal Dermatology Q&A 10]]
}}
==References==
==References==
Withrow, S. (2007) '''Withrow and MacEwen's small animal clinical oncology''' ''Elsevier Health Sciences''
Withrow, S. (2007) '''Withrow and MacEwen's small animal clinical oncology''' ''Elsevier Health Sciences''
Merck and Co (2008) '''Merck Veterinary Manual''' ''Merial''
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[[Category:Dermatological Diseases - Cat]][[Category:Dermatological Diseases - Dog]]
[[Category:Expert Review]]
[[Category:Liver,_Secondary_Tumours]]
[[Category:Liver,_Secondary_Tumours]]
[[Category:Neoplasia]]
[[Category:Neoplasia]][[Category:To Do - Clinical]]