Lymphoid system pathology Flashcards
What happens to the thymus at sexual maturity?
It involutes
When is a very small thymus abnormal?
In neonates
What occurs in thymus atrophy?
Loss of cortical lymphocytes and lobular shrinkage
What can cause thymus atrophy?
Viruses/infectious agents Stress Malnutrition Immunotoxicants - radiation environmental contaminants
What are thymic haemorrhages most common in?
Young dogs
What can cause thymic haemorrhage?
Trauma
Neoplasms
Rodenticide poisoning
Idiopathic
What is the benign tumour of the thymus called?
Thyoma - epithelial cell tumour
What is a malignant tumour of the thymus called?
Thymic carcinoma
What thymic tumours are common in cats and cows?
Thymic lymphomas
What are the two main structures that make up the spleen?
Red and white pulp
What is the red pulp for in the spleen?
Erythrocyte storage and filter
What is the white pulp made up of in the spleen?
Macrophages, antigen presenting cells, lymphocytes
What can cause splenic atrophy?
Cachexia (wasting)
Chronic radiation
Being old
What is an incidental finding in the spleens of old dogs?
Siderotic plaques - crusty bits from haemosiderin/calcium deposits
What can build up in the spleen abnormally?
Erythropoietin - iron deposits
Amyloid
What is splenic infarction?
Local area of peracute ischaemia
What can cause splenic infacrction?
Thrombi
Neoplasia
What does an acute infarct look like?
Dard red, raised, ahemorrhagic
What does a chronic infarct look like?
Grey/white, wedge shaped, sharply demarcated
What are affected by splenic torsion/volvulus
Large dog breeds
Pigs
What happens in splenic torsion?
Complete twist of the gastrosplenic ligament
What can splenic rupture cause?
Haematoma
Spleen fragments disseminate into omentum
What is a splenic haematoma?
Bulging mass on spleen
What are some examples of pathogens causing splenitis?
Anthrax
Salmonellosis
Strep
TB
What is nodular hyperplasia of the spleen found in?
Older dogs
What are predominantly in nodular hyperplasia of the spleen?
Lymphocytes
Can lead to haematoma
What is extramedullary haematopoiesis?
Development of blood cells in tissues outside the medullary cavity of bone
What are the two main tumours of the spleen?
Haemangiosarcoma - malignant tumour from vascular endothelium
Lymphoma
What can cause atrophy of the lymph nodes?
Viral infections Malnutrition/cachexia Old age Toxins Absence of antigenic stimulation
What causes haemosiderin deposition in the lymph nodes/spleen?
Haemorrhage or prolonged stasis
Iron injections in piglets
Melanin
What can cause gas accumilation in lymph nodes?
Drainage of emphysematous lesions
What can cause lymph cysts?
Poor downstream drainage so lymph accumilates
What pathogens can cause lymphadenitis (inflammation of lymph node)?
Corynebacterium pseudotuberculosis
Strep equi equi
TB
Feline coronavirus
What bacteria causes caseous lymphadenitis?
Corynebacterium pseudotuberculosis
What bacteria cause granulomatous lymphadenitis?
Mycobacterium bovis - TB
What is the main primary tumour of lymph nodes?
Lymphoma
What is the main secondary tumour of the lymph nodes?
Carcinomas - metastatic
What can lymphatic rupture cause?
Chylothorax
What is a lymphoma?
Neoplastic lymphoid cells in solid lymphoid organs/tissues
What is leukaemia?
Neoplastic cells arising from the bone marrow that may have detectable neoplastic cells circulating in the blood
What is the most common type of lymphoma?
Multicentric lymphoma
What cells are affected in multicentric lymphoma?
B and T lymphocytes
Where does multicentric lymphoma originate from?
The lymphoid and non lymphoid organs
What cells does cutaneous lymphoma affect?
T cells
What is the name for cutaneous lymphoma which targets the epithelium?
Mycosis fungoides
What are the main symptoms of cutaneous lymphoma/mycosis fungoides?
Diffuse erythema, scaling, hypopigmentation, nodules
What are the different types of alimentary lymphoma?
Segmental or diffuse
T or B cell
Where do alimentary lymphomas metastasise to?
Mesenteric lymph nodes
What viruses can cause lymphoma?
Feline leukaemia virus
Gammaretrovirus
Bovine leukaemia virus
How does feline leukaemia virus cause lymphomas?
Neoplastic transformation caused by insertional mutagenesis
How does bovine leukaemia virus cause lymphomas?
Carries additional genes that encode differnet proteins
What lymphoma can affect calves that isnt BLV?
Sporadic lymphoma
What is a lymphomatous disease of domestic fowl?
Marek’s disease
What is marek’s disease caused by?
Alpha herpes virus
