Pathology of Hemolymphatics Flashcards
<p>Where in the body does hematopoiesis occur?</p>
<p>bone marrow, liver, spleen</p>
What is hematopoiesis?
the proliferation and orderly differentiation of hematoloogic cell lineages from pleuripotent stem cells and progenitors
What are some positive regulators of hematopoesis?
erythropoietin, thrombopoietin, and cytokines (GM-CSF)
What are some negative regualtors of hematopoiesis?
inflammation, hormones, drugs, toxins, and infectious agents
What are the steps of erythroid maturation?
rubriblast to prorubricyte to rubricyte to metarubricyte
What are the steps of myeloid maturation?
myeloblast to promyelocyte to myelocyte to metamyelocyte to seg and band
What is physiologic hyperplasia?
the increased demand for RBCs, granulocytes, and platelets
What are some peripheral manifestations in bone marrow?
leukocytosis, regenerative anemia, and extramedullary hematopoiesis
What is leukocytosis?
increased white blood cell count
What are the causes for hypoplasia, aplasia, and atrophy in bone marrow?
decreased demand, increased destruction, and genetic
What are some causes/processes for increased destruction of bone marrow?
immune-mediated, infiltrative disease, paraneoplastic, and exogenous
What is an example of an infiltrative disease that causes increased destriction to bone marrow?
myelophthisis - replacement of BM by non-native issue/cells leading to pancytopenia
What are some examples of paraneoplastic syndromes?
anemia, neutropenia, thrombocytopenia
What type of exogenous agents cause increased destruction in bone marrow?
infectious (parvovirus, FeLv, FIV, EIA, Ehrlichia) and chemical (antimicrobials, chemotherapeutics, phenylbutazone, bracken fern, and estrogen)
What are some categories of bone marrow neoplasias?
lymphoproliferative disease, myeloproliferative disease, and metastatic
What are some examples of neoplasias that arise from lymphoproliferative disease?
lymphoma, leukemia, plasma cell tumor, multiple myeloma
What are some examples of neoplasias that arise from myeloproliferative disorders?
progenitor-derived neoplasms with bone marrow and hematologic involvement
What causes serous atrophy of fat?
any animal that is undergoing a negative energy balance for a long amount of time (starvation or cancer related)
What is myelofibrosis?
when bone marrow stroma and parenchyma is replaced by fibrous connective tissue
What is the structure of the thymus?
multilobular with capsule, cortex, and medulla
What is the function of the thymus?
it is the site of T cell production and maturation
What lymphatics are associated with the thymys?
only efferent
What does the cortex of the thymus do?
produces immunocompetent naïve T-cells which are then sent to the medulla
What are epithelial reticular cells?
isolates of naïve T cells from antigen exposure
What do tingible-body macrophages do?
break down deleted T-cells
What does the medulla of the thymus contain?
immunocompetent naïve T-cells
What are Hassall’s corpuscles?
confined epithelial cells
What can cause hypoplasia of the thymus?
SCID in arabian foals and mice
What does SCID stand for?
severe combined immunodeficiency
What causes SCID in arabian foals?
there is a defect in DNA protein kinase (premature stop codon)
What is the pathogenesis of hypoplasia of the thymus?
enzyme defect to inadequate gene rearrangement to no T or B receptor to apoptosis of lymphocyte precursors to few functional T and B cells to poor adaptive immune response to death by 5 months of age
What does thymic atrophy occur in response to?
environmental toxin or systemic disease
What is thymic atrophy not to be confused with?
involution
What is thymitis?
inflammation of the thymus
What does circovirus infection in pigs cause?
pyogranulomatous thymitis
What is a thymoma composed of?
neoplastic thymic epithelial cells and non-neoplastic T-lymphocytes
Where are thymomas typically located?
in the cranioventral thorax and may impinge on nearby structures (esophagus, trachea, and vessels)
Do thymomas typically occur to older or younger animals?
older animals
Where are thymic lymphomas located?
in the mediastinum
Microscopically, what do thymic lymphomas look like?
sheets of neoplastic lymphocytes
What is the structure of the spleen?
capsule, smooth muscle trabecula, vessels, and NO lymphatics
What is the flow of blood through the spleen?
trabecular artery to central artery (PALS) to penicillar artery to sheathed arteriole (macrophages) to capillary to sinuses (red pulp)
What is the red pulp made up of?
sinuses and splenic cords
What are the sinuses of the red pulp?
discontinuous endothelium
What are the splenic cords of the red pulp?
reticular fibers and macrophages, T and B cells, plasma cells, and extramedullar hematopoiesis
What is the white pulp of the spleen made up of?
peri-arteriial lymphatic sheaths, lymhoid nodules, and marginal zone
What are peri-arterial lymphatic sheets?
T-cells around central arteries
What are lymphoid nodules in the spleen?
B-cell areas adjacent to PALS; may contain germinal centers
What is the marginal zone of the spleen?
it is located external to lymphoid nodules and PALS and is the interface with red pulp
What is the marginal zone of the spleen made up of?
T and B cells, plasma cells, macrophages, and dendritic cells
What are the functions of the spleen?
filtration, immunologic, hematopoiesis, and storage
What is the purpose of filtration in the spleen?
erythrocyte removal and removal of particulates
What does the spleen store?
blood, iron, and recycling
How does the spleen respond to injury (8)?
inflammation, hyperplasia, hematopoiesis, lymphoid atrophy, necrosis, hemorrhage, hemosiderosis, and neoplasia
What is diffuse enlargement of the spleen known as?
splenomegaly
What causes splenomegaly?
congestion, extramedullary hematopoiesi, and amyloidosis
What are some types of congestion that lead to splenomegaly?
CHF, torsion, epticemia, viremia, and barbituates
What are some types of extramedullary hematopoiesis processes that cause splenomegaly?
AIHA and anaplasmosis
What causes nodules in the spleen?
abscesses, granulomas, hematoma, and neoplasia
What can cause splenic contraction/atrophy?
hemorrhage/hypovolemia and lymphoid atrophy
What are hemosiderotic plaques?
small plaques that form on the surface of the spleen made up of hemosiderin and bilirubin
What are splenic explants?
accessory spleens
What do primary splenic neoplasias arise from?
cell populations that normally exist in the speen: lymphocytes, macrophages, endothelial cells, and smooth muscle
What is the path of flow of the lymphatic system?
interstitial fluid to afferent lymphatics to subcapsular space of draining lymph node to interaction with immune cells to efferent lymphatics to other nodes to the thoracic duct to subclavian veins to the cranial vena cava
What are the functions of the lymphatic system?
lymph drainage, innate and adaptive immunity, and transport of fat and fat-soluble vitamins via lacteals
What causes hypoplasia of the lymph nodes?
SCID
What causes atrophy of lymph nodes?
lymphoid depletion
What causes lymphadenomegaly?
lymphoid/reactive hyperplasia, inflammation, primary neoplasia, and secondary neoplasia
What is inflammation of the lymph node called?
lymphadenitis
What is a primary neoplasia of the lymph node?
lymphosarcoma
What are some secondary neoplasias that affect the lymph nodes?
carcinoma, round cell tumors, and sarcomas
What exudate is associeated with lymphadenitis?
suppurative, eosinophilic, pyogranulomatous, and granulomatous
Lymphadenitis is a common response to infection by what?
bacteria, fungi, viruses
What is an example of a bacteria that causes lymphadenitis in horse?
streptococcus equi ssp. Equi
What is an example of a virus that causes lymphadenitis in swine?
procine circovirus (causes granulomatous lymphadenitis)
What is an example of a bacteria that causes lymphadenitis in sheep?
corynebacterium pseudotuberculosis; caseous lymphadenitis
What is lymphoma (like specifically what is it)?
neoplastic proliferation of lymphocytes
What causes lymphoma?
sporadic or viral-associated or other
What is large cell lymphoma caused by?
lymphoblastic (immature) cells
What is small cell lymphoma caused by?
indolent (mature) cells
What are the lymphoid immunophenptypes?
T cell, B cell, plasma cells, and multiple myelomas
What paraneoplastic syndromes are associated with lymphoma?
cytopenias, anemia, and hypercalcemia
Canine lymphoma is the most common of canine ________.
malignancies
80percent of canine lymphomas are of what type?
multicentrac - generalized lymphadenopathy
20-40 percent of other canine lymphomas are associated with what clinical signs?
weight loss, anorexia, fever, hepato-/splenomegaly
Where are the 20-40percent of canine lymphomas that arent multicentric located?
thymic, cutaneous, epidermotropic, and ocular
What type of cells are most of the canine lymphomas made up of?
B-cells (60-80percent )
Are most canine lymphomas large cell or small cell?
large cell
Are most feline lymphomas large cell are small cell?
large cell
What is the ratio of B-cell to T-cell types of lymphoma in cats?
fifty fifty
FeLv associated lymphomas typically occur to what age of cats?
4-6 year olds
FeLv associated lymphomas typically localize where?
mediastinum or spine
Non-FeLv associated lymphomas typically occur in what age of cats?
older cats
Non-FeLv associated lymphomas are typically localized where?
GI/abdominal: 70percent intestinal, 30percent liver, spleen and kidney
other sites: nasal, CNS, ocular, cutaneous
What is Marek’s disease?
T-cell lymphosarcoma of 2-5 month old chickens
What is Marek’s disease caused by?
oncogenic herpesvirus
How is Marek’s disease transmitted?
horizontal transmission via infected feather follicle dander
Where does Marek’s disease localized?
liver, brain, peripheral nerves, and other organs
What is lymphoid leukosis?
B-cell lymphosarcoma of chickens greater than 4 months old
What is lymphoid leukosis caused by?
avian retrovirus
Where does lymphoid leukosis localize?
Bursa of Fabricius, liver, spleen, ovary, and other organs
What is the most comon form of bovine lymphoma?
adult form
What is the adult form of bovine lymphoma caused by?
bovine leukemia virus - a retrovirus
Where does bovine lymphosarcoma typically manifest?
HURLS
What does HURLS stand for?
heart, uterus, renal and retrilobular, lymph nodes, stomach, and spinal
At what age does the adolescent form of bovine lymphoma occur?
6-30 months of age
Where does adolescent bovine lymphoma localize?
in the thymus and bone marrow
When does juvenile bovine lymphoma infect cattle?
in calves under 6 months old
What type of lymphoma is associated with juvenile lymphoma?
multicentric often with organ involvement
What is MALT?
mucosal associated lymphoid tissue
What organs are part of MALT?
tonsils, Peyer’s patches, gut associated lymphoid tissue, bronchial-associated lymphoid tissue, rectoanal mucosal-associated lymphoid tissue and others
MALT is an important part of what type of immunity?
mucosal
What pathogens can invade MALT?
bovine herpesvirus 1, salmonella, CSF, FMD, brucella abortus, Mycobacterium avium susbp. Paratuberculosis, prions
