Haematopoietic System Flashcards
What organs make up the haematopoietic system?
Myeloid tissue-
bone marrow
blood cells
mono-nuclear phagocyte system
Lymphoid tissue-
lymph node
spleen
thymus
accessory lymph tissue
What is the structure, function and circulation in lymph nodes?
Function- filtration of lymph, immune response
Structure-
Outer cortex- follicles (mostly B cells)
Inner cortex- paracortex (T cells)
Medulla- mostly B cells and macrophages
Circulation-
Afferent lymphatics- subcapsular sinuses- trabecular sinuses- medullary sinuses- efferent lymphatics- thoracic duct
What are the three different general responses to lymphnode injury and what are the causes?
Enlarged lymph nodes-
Lymphadenitits, hyperplasia, hyperplasia of macrophage system, primary neoplasia, secondary neoplasia
Small lymph nodes-
lymphoid atrophy, degeneration, hypoplasia
Lymphadenopathy-
Enlargment of lymph nodes of unknown cause, localised or generalised
What causes lymphadenitis?
What is the difference between chronic and acute?
Lymphadenitis- inflammatory response to an infectious agent within the node
Acute- usually result of regional lymph node draining a site of inflammation and becoming infected
Chronic- LNs become large, irregular and firm due to fibrosis, chronic supprative lymphadenitis, chronic granulomatous lymphadenitis
In chronic supprative lymphadenitis
How does it appear grossly and histologically?
What is the aetiology and pathology of porcine jowl abscess?
Gross- swollen/enlaerged LN with puss filled centre- abscess
Can fistulate to skin surface, response to pyogenic bacteria
Histo- degenerate neutrophils, lytic necrosis, fibrous capsule
Porcine jowl abscess- streptococcus porcinus, colonises oral cavity/tonsils and spreads to mandibular lymph nodes
What is the aetiology of strangles?
Describe its pathogenesis
What are its sequelae?
Chronic supprative lympadenitis
Streptococcus equi subsp equi
Inflammation of the URT- abscesses in the mandibular, retropharyngeal and parotid LN
May fistulate to the surface- can spread to viscera ‘bastard strangles’
Sequelae-
can get drainage to the guttural pouches
supprative/purulent material- guttural pouch empyema- inspissated material- chondroid formation
What agent causes caseous lymphadenitis?
What is the pathogeneis?
How does it appear grossly and histologically?
Corynebacterium pseudotuberculosis- chronic supprative lymphadenitis in sheep and goats, ulcerative lymphangitis in horses and cattle
Pathogenesis-
usually enters via contamination of shear wounds
Drains to regional lymph nodes- superficial more than internal
Gross- enlargment of LN, as lesion progresses- characteristic concentric laminations
Histo- chronic supprative (neutrophils) inflammation, caseous necrosis and fibrosis
With time systemic involvment with abscesses in internal organs
What are the two types of granulomatous lymphadenitis, how do they appear differently grossly?
What are some aetiologies?
How do they appear histologically?
Nodular granulomatous lymphadenitis- focal or multifocal, often white-yellow nodules +/- caseous necrosis/mineralisation
Diffuse granulomatous lymphadenitis- enlarged, pale, dry, firm lymph nodes, loss of architecture
NGL- Myobacterium bovis (TB), Johne’s disease, migrating larvae
DGL- porcine circovirus type 2, cryptococcus neoformans
Histo- macrophages, multinucleated giant cells, lymphocytes, plasma cells, fibrosis, necrosis +/- mineralisation
The following images where taken from a PM of a Dairy Cow
Grossly describe the appearance of the organ
may be hard with image size but- describe histology
What stain is used in the bottom left corner and what does it idenfity?
Therefore what is the aetiology?
Gross- LN, enlargment with multifocal to coalescing yellow-tan gritty nodules
Histo- granulomatous with central necrosis and mineralisation surrounded by epithelioid macrophages and multinucleated giant cells
Ziehl-Neelsen stain- acid fast bacilli within macrophages
Bovine tuberculosis- TB
can disseminate to organs
A pig had a PM after poor growth, its mesenteric lymph nodes where identified as abnormal
Grossly- diffuse enlargment
Histologically- granulomatous infilatration of the node with large botryoid intracytoplasmic viral inclusions
What is the name of this disease?
What is the agent?
Postweaning multisystemic wasting syndrome (PMWS)
Caused by porcine circovirus type 2
What is benign reactive hyperplasia?
How does it appear grossly and histologically?
Benign reactive hyperplasia-
Immunological reaction- response to antigen presentation or circulating interleukin levels
Causes lymph node enlargment, can be localised or generalised
Gross- moderate enlargment or the node, may bulge on cut setction
Histology-
Proliferation of lymphoid follicles with prominent germinal centres
Increased T cells in paracortex, increased plasma cells in the medullary cords
What metastasises are common in lymph nodes?
How can tumour malignancy be staged?
Secondary- carcinomas, melanomas, mast cell tumours
variable effacement of normal architecture
Stage 0- regional node normal
Stage 1- regional node enlarged, freely moveable
Stage 2- enlarged and fixed
What are the two primary neoplastic diseases of the hematopoietic system, what are examples of both?
Lymphoproliferative disease- lymphoma, lymphoid leukaemia, plasma cell tumour
Myeloproloferative disease- histiocytic neoplasia, myeloid leukaemia, mast cell tumour
What are the neoplastic disorders of lymphocytes?
What can cause the diseases?
Neoplastic lymphoctes- T and B cells
Lymphoid leukaemia- neoplastic lymphocytes in bone marrow/blood
Lymphoma- neoplastic lymphocytes in tissues/organs
one of most common malignant tumour in domestic animals
Both can lead to eachother
Viral infection- cats, cattle, mice, chickens
Hereditary- porcine
What are the different methods of classification of lymphoma?
Anatomical- multicentric, alimentary, thymic, cutaenous, leukaemic
Biologic- low grade, intermediate, high grade (aggressive)
Cellular morphology- cell size, nuclear features, mitotic rate
Immunophenotype- B-cell, T cell, non B/T cell
Classification advanced in humans due to prognastic factors
What are the clinical signs of lymphoma?
Vary!
Non-specific signs- weight loss and loss of apetite
Painless swelling of 1+ lymph nodes
Other signs depending on anatomical location
Retrobulbar- exophthalmos
Thymic- dyspnoea, oesophageal obstruction
Lymphoma can form in different locations describe the gross appearance of the following organs:
Spleen
Kidney
Lymph nodes
Spleen-
Organomegaly- diffuse organ enlargment
Kidney- multiple tan-white to pink nodules within organs
Lymph nodes- enlarged- soft to firm, bulge on cut surface, homogenous, pale tan, foci of necrosis or haemorrhages are common, often firmly attached to surrounding tissue
What dogs are more likely to be infected with canine lymphoma?
Where can the lymphomas be found?
What is myelophthisis?
Middle aged to older dogs
Thymic, renal, splenic, bone marrow, cutaneous, alimentary
Myelophthisis- complete replacement of haematopoietic tissue in the bone marrow by neoplasia/fibrosis/other
What is the most common malignant neoplasm of cats?
Where are the most common neoplasm locations?
What disease is it associated with?
Feline lymphoma
Alimentary > multicentric > thymic > miscellaneous
leukaemis and bone marrow involvment are common
Associated with FeLV
What are the two forms of bovine lymphoma?
What disease is associated with one form?
How is it transmitted?
What cattle are more commonly affected?
What are the commonly affected sites?
Can be Enzootic on sporadic
Bovine leukosis virus- some have persistent lymphocytosis, 3% lymphosarcoma
Transmitted- direct contact, natural bleeding, needles, ear-tg equipment
Adult cattle, especially dairy cattle- multicentric lymphoma of B cell origin
Commonly affected sites of bovine leukosis virus- lymph node, right atrium, abomasum, spinal canal, uterus, kidney
What are the 3 forms of sporadic bovine lymphoma?
Calf form-
<6 mo, symmetrical lymphadenopathy and leukaemia
Terminally- bone marrow involement, sometimes organs
Juvenile form- thymic form
Yearling beef cattle, mediastinal masses
Cutaneous form
2-3 year old cattle
Plaque like to nodular round raised lesions, waxing and waning
Survive 12-18 months, eventual systemis involvment
What is the most common neoplasm in pigs, where is it found, what is predisposed?
What are the different forms of equine lymphoma?
Porcine lymphoma- multicentric
Often <1 year, females increases, hereditary- large white
Seperate forms of equine lymphoma- based on topography
Subcutaneous- females, alimentary, abdominal, splenic, multicentric
What is histiocytic sarcoma?
What breeds are predisposed?
How can they present differently?
How do they appear histologically?
Malignant neoplasia of macrophage or dendritic cells
Breeds- Burnese, Rottweiler, flat coat retriever
Solitary- surrounding joints, subcut, lymph nodes, spleen, liver
Multiple- disseminated histiocytic sarcoma- malignant histiocytosis
aggressive multisystemic disease- spleen, bone marrow, lymph nodes
Histo- masses/diffusely infiltrated composed of atypical histiocytes
What dogs sometimes have siderotic plaques?
How do they appear grossly and histologically?
Older dogs, senile change
Gross- grey/white to yellow, firm encrustation on the splenic capsule, usually in margins
Histology- often contains golden brown pigment, blue-purple mineralisation
What are your DDxs for this spleen picture?
What is needed for diagnosis?
What are the likely sequalae?
Haematoma, haemangioma, haemangiosarcoma
Histology to show its a haematoma
Sequelae- splenic rupture, haemoabdomen, hypovolaemic shock
Chronic granulomatous splenitis can be nodular or diffuse
What causes nodular splenitis in a chicken?
What causes diffuse granulomatous splenitis in a dog?
Nodular- myobacterium avium in a chicken
Diffuse- histoplasma capsulatum
Describe the gross appearance of splenic haemangiosarcoma
How does it appear histologically?
What are the possible sequelae?
Single to multiple discrete to coalescing masses, often drark red
+/- metastases
Histologically- blood filled vascular spaces lines by anaplastic epithelial cells
Sequelae- splenic rupture, haemoabdomen, peritoneal seeding, metastasis
On this image of a lymph node label the following structures:
- Lymphoid follicle
- Germinal centre
- Capsule
- Outer cortex
- Inner cortex
- Medullary cords
- Medullary sinus
What a beautiful diagram
On this image label:
- White pulp
- Red pulp
- Splenic follicle
- Germinal centre
On this image label the following:
- Cortex
- Medulla
- Thymic vasculature
Give a gross description of this organ
Organ- spleen
Diffuse distribution, splenomegaly, Tan colour, soft consistency
Image shows a low power histological image of a 10 year old female, Lab spleen- with chronic severe otitis
What are arrows indicating?
What material might this be?
Accumulations of amorphus eosinophilic material
Amyloid
Incidental finding of rottweiler
Give a gross description
Spleen
Multi focal raised nodules extending into parenchymyma, 1-3cm diameter spherical, yellowish-white
What is abnormal about this high power slide of a spleen
Describe specific features of atypical cells
DDXs?
Diffuse effacement of the spleen by a neoplastic poulation
Round large cell shapes, some irregular shaped, with large and variable nucleus size and high mitosis
DDXs- round cell tumour: lymphoma, histiocytic sarcoma
Give a gross description of this spleen
Any ideas?
Spleen
Multifocal to coalescing nodules upto 5cm diameter, spherical, dark red, soft texture
Haemangiosarcoma, haemangioma, haematoma
What kinds of cells and structures are present?
MD?
Vascular spaces from endothelial cells with blood
MD- haemangiosarcoma
Give a gross description?
Lymph node
Diffuse, irregular nodules, enlarges, pale tan firm
Image shows abnormal high power lymph node
Describe:
Cells size and shape
Nuclear size and shape
Nuclear staining intensity
Mitoses
Diagnosis?
Cell size- large lymphoid cells
Nucleus- large, round to irregular, some indentations of nucelar membranes
Staining- palely basophillic
Frequent mitosis
Diagnosis- lymphoma
