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→Lymphoid Neoplasms
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+* '''Lymphoma''', '''malignant lymphoma''' and '''lymphosarcoma''' are different terms for the same condition.
−
−===== 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.
====Lymphoid Neoplasms====
====Lymphoid Neoplasms====
−See [[Lymphoma]]
−====Lymphocytic Leukaemia====
====Lymphocytic Leukaemia====