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Also known as: '''''Lymphosarcoma'''''
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Also known as: '''''Lymphosarcoma — Malignant Lymphoma'''''
    
==Introduction==   
 
==Introduction==   
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[[Category:Neoplasia]]
 
[[Category:Neoplasia]]
 
[[Category:Splenic Neoplasia]]
 
[[Category:Splenic Neoplasia]]
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===== Classification=====
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* '''Cytological classification'''.
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** Well differentiaed (lymphocytic)
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*** The malignant cells represent normal lymphocytes, although in excessive numbers.
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** Poorly differentiated (lymphoblastic).
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*** The malignant cells represent atypical lymphocytic cells with lymphoblastic characteristics.
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* '''Tumour distribution'''
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** Nodular/ follicular.
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*** A well organised pattern of slow growth.
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*** No metastasis.
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*** Are of the B-lymphocyte type.
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** Diffuse.
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*** Result in effacement of normal lymphoid architecture by a very homogeneous population of lymphoid cells.
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* '''Anatomical classification'''
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** Thymic.
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** Only the [[Thymus - Anatomy & Physiology|thymus]].
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** Alimentary.
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*** Gut and associated lymphoid tissue.
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** Multicentric.
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*** Widespread involvement of lymph nodes.
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** Cutaneous lymphoma.
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*** Usually presents as generalised skin disease, but is a malignant transformation of T cells with a propensity for  pithelial sites
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* '''Type of lymphocyte'''
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** T-cell.
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** B-cell.
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** NK-cell.
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* '''Time scale'''
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** Acute.
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** Chronic.
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=====Prevalence=====
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* Order of prevalence in UK: cats, dogs, cattle, pigs and sheep.
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** In the cat and ox, viral agents have been identified as the causal agents.
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* Lymphoma is one of the prevalent neoplasms in the dog.
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** 80% of cases affect the 5 to 11 year old age group. 
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** The incidence is about 28 per 100,000 dogs. 
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** Blood of affected dogs shows neither a relative nor absolute increase in the number of lymphocytes until the late stages of the disease.
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*** When this stage is reached, poorly differentiated cells may appear in the blood.
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* FeLV is an important cause of lymphoma in the cat.
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** 70% of cats with lymphoma will test positive for FeLV.
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** FeLV also causes a number of non-neoplastic diseases.
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*** Anaemia.
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*** Leukopaenia.
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*** Thymic atrophy. 
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* Cattle suffer both lymphosarcoma and leukosis in a variety of cytological forms.
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** Bovine lymphoma is caused by [[Bovine Leukaemia Virus]] (BLV).
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*** A retrovirus.
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*** There is a juvenile form of bovine lymphoma seen in young cattle which is not associated with BLV.
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=====Species Differences=====
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* The form of the disease may differe between species.
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* '''Feline'''
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** Alimentary.
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*** Affects the mesenteric lymph nodes, intestine, [[Liver - Anatomy & Physiology|liver]], spleen , and potentially the kidney.
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** Thymic
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*** Presents as a thymis mass, also in the mediastinal lymph nodes.
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*** The pleural lymph nodes and the [[Liver - Anatomy & Physiology|liver]] may potentially be affected.
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** Multicentric
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*** Found in the peripheral and deep lymph nodes, [[Liver - Anatomy & Physiology|liver]] and spleen.
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**** The kidney may sometimes be affected.
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** Renal
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*** The kidney and other abdominal organs are affected.
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** Leukaemic
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*** Affects the bone marrow alone.
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*** This form is rare.
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* '''Canine'''
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** Alimentary.
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*** Affects the mesenteric lymph nodes, pancreatic lymph nodes, intestine, and potentially the [[Liver - Anatomy & Physiology|liver]].
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** Thymic.
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*** Thymic and mediastinal masses.
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** Multicentric.
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*** Affects the peripheral and deep lymph nodes, [[Liver - Anatomy & Physiology|liver]], spleen and kidney.
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* '''Bovine'''
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** Thymic.
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*** Mainly affects adults.
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*** Thymic and mediastinal masses.
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*** Some lymph nodes are also affected.
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** Multicentric.
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*** Mainly affects yopung adults.
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*** Affects the peripheral and deep lymph nodes, spleen, [[Liver - Anatomy & Physiology|liver]] and kidney.
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* '''Equine'''
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** Takes mainly an alimentary form.
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** Can rarely be cutaneous.
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* '''Porcine'''
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** Mainly multicentric.
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*** Lymph nodes, [[Liver - Anatomy & Physiology|liver]], spleen.
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* '''Ovine'''
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** Uncommon.
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** May be multicentric or thymic.
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