Haematopoietic system Flashcards
Primary Haematopoietic neoplasia:
Solid vs circulating tumours
solid = discrete mass - lymphoma
Circulating = leukaemia
Define lymphoid leukaemia
Neoplastic lymphocytes in bone marrow/ blood.
ie circulating
Define lymphoma
Neoplastic lymphocytes in tissues/ organs
ie Solid
Name and describe the four classifications of lymphoma.
- Anatomical - ie location
- Cellular morphology - cell size, nuclear features, mitotic rate
- Immuno-phenotype - B/T cell or Null
- Biologic behaviour - Low - high grade
True or false.
Low grade tumours are less responsive to chemotherapy than high grade.
Why?
True.
Low grade (indolent) tumours are slower growing and therefore less responsive to therapies
Which immuno-phenotype shows a better response to therapy?
B cell
Multicentric
Generalised, found in multiple lymphocytes.
What are the common featuers of primary bone neoplasia?
- Hypercellular marrow: uncontrolled proliferation of the neoplastic haematopoietic cells
- Anemia: non-regenerative anemia - ineffective erythropoiesis. Bone marrow is occupied by neoplastic haematopoietic cells = competition for nutrients &/or space (myelophthisis). Neoplastic cells secrete inhib factors
- Thrombocytopenia +/- Neutropenia: not always present
- Leukemic cells in peripheral blood: immature stages of haematopoietic cells in peripheral blood commonly seen in haematopoietic neoplasia.
What is the difference between lymphoproliferative and myeloproliferative diseases?
Neoplastic transformation of lymphoid cell lines = lymphoproliferative.
Neoplastic proliferation of one or more bone marrow cell lines = myeloproliferative (granulocytes, erythrocytes, monocytes etc)
Describe clinical signs associated with lymphoma.
- Non-specific - wt loss and anorexia
- Lymphandenopathy - painless swelling
- Depending on anatomical location
- Exophthalmos - retrobulbar LN
- Dyspnoea, tracheal/ oesophageal obstruction - thymic
- Diarrhea, obstruction, melena - Alimentary
Describe the gross appearance of a lymphoma lesion.
- Lymphnodes - enlarged
- Soft to firm, bulge on cut surface
- Pale tan - white
- Homogenous appearance
- Focal necrosis/ haemorrhage
- Fibrosed to surrounding tissue
- Organomegaly
- Multiple tan-white-pink organ nodules
Name the most common canine hematopoietic neoplasia.
Canine lymphoma
What percentage of canine lymphoma show multicentric lymphoma?
85%
How does canine lymphoma result in hypercalcemia?
The tumours produce pth-like factor which does not respond to normal negative feedback.
(also occurs in anal-sac carcinomas)
Name the most common malignant neoplasm of cats.
Feline Lymphoma
Which virus is feline lymphoma associated with?
FeLV
- 10-20% of cats with lymphoma are FeLV positive
- Occurs in young cats
- Mediastinal and multicentric forms possible
Which form of feline lymphoma are most common?
Order these as most common onwards..
Misc, multicentric, alimentary, thymic
Alimentary > multicentric > thymic > misc
Which form of lymphoma is characteristic of Enzootic Bovine Lymphoma?
Which virus is associated with the disease?
Multicentric lymphoma of b cells.
Bovine Leukosis virus, retrovirus
Remember: 30% don’t initially present with lymphoma - persistent lymphocytosis
3% of cattle develop lymphoma
How is BLV transmitted?
Through transmission of viral infected lymphocytes:
- Direct contact
- Natural breeding
- Contaminated needles
- Dehorning/ ear-tagging equipment
- Arthropods - horizontal spread
Which sites are commonly affected by Enzootic Bovine lymphoma?
(x6)
- LNs
- Right atrium
- Abomasum
- Spinal canal
- Uterus
- Kidney
How is sporadic bovine lymphoma characterised between these different age groups:
- Calves <6m?
- Juvenile - yearlings?
- 2-3 years?
- Multicentric lymphoma, symmetrical lymphadenophathy/ leukemia, bone marrow/ organinfiltration
- Mediastinal lymphoma - large cranial thoracic/ lower cervical masses - resp distress and wt loss
- Plaque-like to nodular raised skin lesions, lesions may come and go, can survive up to 18 months, eventually leads to systemic involvement
Which groups are most at risk of developing porcine lymphoma?
Where are lesions commonly found?
- Females
- Large white - autosomal recessive
- <1 yo
- Multicentric - visceral LN, spleen, liver, stomach, intestine, kidney, bone marrow
- Mediastinal
Name and describe three types of plasma cell tumours (benign and malignant)
- Plasmacytoma
- Cutaneous - common in dogs, surgery is curative - benign
- Extramedullary - don’t arise from bone marrow, may affect GI tract, may mets to LNs
- Plasma cell myeloma - aggressive and malignant tumours arising from bone marrow
Describe this lesion.
The pinna of this dog has a 1cmx1cm nodular red mass which protrudes from the surface of the ear. The mass is firm to touch and shows well demarcation.
Pinnal cutaneous plasmacytoma
Describe the histological finding associated with plasmacytomas.
(x6)
- Sheets of rounds cells
- Show anisocytosis - uneven size
- Show anisokaryosis - variation in nuclear size
- Clock face pattern of dense chromatin seen
- Halo of Golgi
- Multinucleated giant cells may be seen
Describe the gross findings associated with multiple myeloma.
- Affected bone exhibit multiple dark-red soft / gelatinous tissue nodules filling areas of bone resorption / lysis.
- 2/3 of dog cases show osteolytic lesions
- Lesions can be found in any haematopoietically active bone, but are most common in the vertebrae.
True or false.
Histological signs of multiple myeloma are similar to that of plasmacytoma.
Describe the histo changes.
True
Masses composed of sheets of neoplastic plasma cells in the bone marrow
What clinical signs are commonly associated with plasma cell myeloma?
- Pain in affected bones - lameness
- Spinal cord compression leads to paraplegia - pathological ventrebral fracture
- Hypercalcemia - osteolysis
- Bence-jones proteinuria
- Monoclonal gammopathy
- Hyperviscosity syndrome - increased blood viscosity
Bence-Jones protein
Monoclonal globulin protein/ immunoglobulin light chain found in urine
Decribe this serum electrophoresis.
Monoclonal gammopathy
Histiocyte
A mononuclear phagocyte
- What are the two types of reactive histiocytosis?
- True or False - It is not considered a true neoplastic disorder.
- What is the cell of origin?
- Describe the clinical signs.
- Cutaneous - limited to the skin, systemic - affects skin and other organs
- True - it is an immunoregulatory disorder - controlled by immunosuppressive therapy
- Activated dermal dendritic cell (APC)
- Multifocal skin masses which come and go and are progressive
Decribe the histo features of canine reactive histiocytosis.
Exophytic
Lymphocytes and inflammatory cels at the base of the tumour
Regression due to apoptosis of histiocytes
A malignant neoplasia of macrophages or dendritic cells.
Which breed of dog are associated with the disease?
Histiocytic sarcoma
Rottweiler, bernese mountain dog, flat coats
Describe the differences between solitary and multiple lesions which occur in histiocytic sarcomas.
Multiple - disseminated (malignant) - occurs in spleen, lung, LNs, bone marrow, skin, subcutis
Solitary - surround joints, subcutis, liver, lungs or splee, brain
What histological features characterise disseminated histiocytic sarcomas?
Masses/ diffuse infiltrates composed of atypical histiocytes.
May retain the ability to phagocytose - haemophagocytosis = non-regnerative anaemia
Why are eosinophils often associated with mast cell tumours?
Which type of stain is used to identify mast cells definitively?
Mast cells secrete granules which secrete eosinophilic chemotactic factor which cause eosinophils to move into the site.
Toluidine blue
Describe the structure and function of the lymphnodes.
Outline the circulation of lymph through the lymphatics.
Structure - Outer cortex contains follicles (mainly b cells), inner cortex (mainly t cells), medulla (mainly b cells and macrophages)
Function - immune response and lymph filtration
Afferent lymphatics – subscapular sinuses – trabecular sinuses – medullary sinuses – efferent lymphatics – thoracic duct
What disease situations may lead to enargement of the lymphnodes?
- Lymphadenitis
- Lymphoid hyperplasia
- Hyperplasia of monocyte/ macrophage system
- Primary or secondary neoplasia
Lymphodenopathy
Enlargement of the lymphnodes due to an unknown cause.
Lymphandenitis
An inflammatory response to an infectious agent within the node
What gross changes are associated with chronic lymphandenitis?
LNs are:
- Large
- Irregular
- Firm - fibrosis
- Supprative/ granulomatous inflammation
Describe the gross appearance of chronic suppurative lymphandenitis.
Name two bacteria which can lead to these findings.
Swollen LNs with a puss filled centre (LN abscesses), may fistulate (burst) to the skin surface,
They are a response to pyogenic bacteria such as:
- Strep equi var equi (zooepi is also pyogenic)
- Strep porcinus - porcine jowl abscesses
Describe the pathogenesis of bastard strangles.
Which LNs are often affected by strangles?
Inward bursting of LN abscesses leads to swallowing of pus - intestinal spread of bacteria.
Parotid, retropharyngeal, mandibular LNs
Outline the pathogenesis of Porcine Jowl Abscess.
Ingested bacteria colonise oral cavity/ tonsils and spread to mandibular LNs
The bacteria causes caseous lymphadenitis of the mediastinal LNs.
Corynebacterium pseudotuberculosis
- Outline the pathogenesis of Corynebacterium pseudotuberculosis.
- How do clinical lesions differ between the main domestic species?
- Enters via contamination of shear wounds (rarely inhalation), drains to regional lymphnodes (superficial more affected than deep)
- Prescapular/ prefemoral
- Species
- Sheep/ goat - chronic suppurative lymphandenitis
- Horse/ cattle - Ulcerative lymphangitis
- Horse - Pectoral abscess
Describe this lesion
This lymphnode is diffusely enlarged. The normal architecture is completely disrupted by a lamellar formation of white pus and firm fibrous tissue.
Chronic diffuse severe suppurative fibrosing lymphandeitis
Corynebacterium pseudotuberculosis
Focal shearing wound abscessation of the scapular LN.
Corynebacterium pseudotuberculosis
Describe this lesion
Focal swelling of the mandible of a piglet - could be LN salivary gland or neoplastic?
Skin of the mass shows multifocal to coelescing irregular areas of haemorrhage.
The mass is approximately 20x20 cm
Chronic focal severe suppurative lymphandenitis - Porcine jowl abscess
Streptococcus porcinus
Describe this lesion
This lymphnode shows multifocal to coelescing areas of disruption of architecture by a white to yellow mass. There is a focal area that is severely affected (2x1cm). The mass is firm to oozing on the cut surface.
Chronic multifocal-coelecing mod-severe granulomatous lymphandenitis
Mycobacterium bovis
(MAP, Actinobacillus lignieresii, parasitic)
Diffuse granulomatous lymphadenitis caun be caused by what?
How do LNs appear grossly?
Enlarged, firm, pale, loss of architecture
PCV2
Histoplasma capsulatum
Blastomyces dermatitidis
Cryptococcus neoformans
Describe this lesion
Area of central necrosis surrounded by epitheloid macrophages and fibroblasts (capsule)
Granulomatous lymphandenitis
Mycobacterium bovis
Acid fast Mycobacterium bacteria stained with Ziel Nielson
PMWS
Postweaning multisystemic wasting syndrome
PCV2
Diffuse enlargement of the mesenteric lymphnodes - PMWS (PCV2)
Botryoid intracytoplasmic viral inclusions are found in what condition?
PMWS - PCV2
What?
Cause?
Reactive lymphoid hyperplasia
- Proliferation of lymphoid follicles
- Increased T cells in paracortex
- May have increased plasma cells in medullary cords
Caused by: Ag response, Interleukin circulating
What types of tumours commonly metastasise to the lymphnodes?
Carcinomas
Melanomas
Mast cell tumours
Describe the three stages used to assess tumour malignancy.
Assessment of regional lymphnodes.
Stage 0 - LN normal
Stage 1 - LN enlarged but freely moveable
Stage 2 - LN enlarged and fixed
What is the function of the thymus?
Proliferation and maturation of T cells
Which two types of neoplasm are possible of the thymus?
Thymic lymphoma - T cell
Thymoma - epithelial
Describe this lesion
Diffuse enlargement (rounded edges) of the spleen. The tissue appears to be friable with a beige to orange discolouration.
Chronic diffuse moderate lymphoplasmasitic amyloidosis of the spleen
Idiopathic
Splenic torsion may be a sequelae to what GIT disorder in the dog?
Splenic torsion
Describe this lesion
Multifocal to coelescing white round white lesions throughout the splenic tissue. (miliary)
Chronic disseminated severe suppurative hepatitis
Francisella tularensis (Yersinia pseudotuberculosis)
What aetiological agents can cause septicaemic splenitis?
Anthrax
Erysipelas
African Swine fever
What aetiological agent causes granulomatous splenitis in the chicken?
Mycobacterium avium
What aetiological agent can cause diffuse granulmatous splenitis in the dog?
Histoplasmosis
Differentials for splenic masses
Benign nodular hyperplasia
Neoplasia - haemangiosarcoma
Lymphoid hyperplasia of the spleen
White pulp
Benign endothelial tumour of the spleen
Haemangioma
Describe this lesion
Multifocal 5x5x5cm nodular masses protruding from the splenic surface, poor demarcation on histology. Firm to touch and beige in colour.
Splenic haemangiosarcoma
Sequelae: splenic rupture, haemoabdomen, peritoneal seeding and metastasis
