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