15b – Intro to Hematopoietic Flashcards
What does primary hematopoietic neoplasia result from?
- Clonal expansion of hematopoietic cell types
What do primary hematopoietic tumours primarily affect?
- BONE MARROW
- Blood (leukemia)
- Lymphoid tissues (lymph node, spleen, etc.)
What are the 4 common features of primary bone marrow neoplasia?
- Hypercellular marrow
- Anemia
- Thrombocytopenia +/- neutropenia
- Leukemic cells in peripheral blood
Hypercellular marrow (primary bone marrow neoplasia)
- Reflects uncontrolled proliferation of neoplastic hematopoietic cells
Anemia (primary bone marrow neoplasia)
- Non-regenerative anemia due to INEFFECTIVE ERYTHROPOIESIS
o Competition for nutrients and/or space
o Inhibitory factors may be released from neoplastic cells
Thrombocytopenia +/- neutropenia (primary bone marrow neoplasia)
- Not present in all myeloproliferative diseases
Leukemic cells in peripheral blood (primary bone marrow neoplasia)
- Immature stages of hematopoietic cells in peripheral blood
What are the 2 broad categories of hematopoietic tumours?
- Lymphoproliferative disease
- Myeloproliferative disease
Lymphoproliferative disease: ‘definition’
- Neoplastic proliferation of lymphocytes causing a spectrum of disease
o Lymphoid leukemia: bone marrow and circulation
o Lymphoma: lymph nodes/tissues/organs with relatively normal blood profile
o *can do the ‘opposite’ so hard to separate them
Lymphoproliferative disease: 3 types
- Lymphoma
- Lymphoid leukemia
- Plasma cell tumours
Lymphoid leukemia (clinical pathology)
- Malignant hematopoietic neoplasms that originate in bone marrow
- Significant numbers of neoplastic cells circulating in blood
- *lymphocytic (T or B lymphocyte) in origin
- Acute or chronic
Lymphoma (lymphosarcoma)
- *one of the MOST COMMON MALIGNANT NEOPLASMS in domestic animals
- Can be
o Sporadic
o Hereditary: porcine lymphoma
o Viral: FeLV in cats, BLV in cattle
Classifications of lymphomas: 5 different ways
- Anatomical classification
- Cellular morphology
- Immuno-phenotypes
- Biologic behaviour (low to high grade)
- Histologic pattern (diffuse vs. follicular)
Anatomical classification of lymphoma
- Multicentric
- Alimentary
- Thymic
- Cutaneous
- Misc.
- Leukemic
Multicentric
- Generalized involvement of lymph nodes, +/- liver, spleen, marrow or other organs
Alimentary
- Nodular to segmental involve of GI tract, especially intestine
Mediastinal/thymic
- Involvement of cranial mediastinum/thymus
Cutaneous
- Both epitheliotropic (T-cell) AND non-epitheliotropic (mostly B cell) forms
Miscellaneous (anatomical classification)
- Renal
- Ocular
- Cardiac
- Neural
- Etc.
leukemic lymphoma
- When lymphoma invades marrow and occurs in blood
o *hard to separate from lymphoid leukemia
Cellular morphology for classification of lymphoma
- Cell size
- Nuclear features
- Mitotic rate
- *multiple classifications based on cytologic features
Small cell lymphoma with low mitotic rate leads to
- Slow progression
- Poor response to chemotherapy
Large cell lymphoma with high mitotic rate leads to
- Rapid progression
- DO respond to chemotherapy
Immune-phenotype for classification of lymphoma
- B-cell
- T-cell
- Non B/T
B vs. T cell lymphoma
- B cell lymphomas may have better survival profiles in response to treatment compared to T cell
What are the non-specific clinical signs of lymphoma?
- Weight loss
- Loss of appetite
- *painless enlargement of 1+ lymph nodes (lymphadenopathy)
What are the clinical signs of lymphoma in the retrobulbar lymph nodes?
- Exophthalmos
What are the clinical signs of lymphoma in the thymus?
- Dyspnea
- Esophageal obstruction
What are the clinical signs of lymphoma in the alimentary?
- Diarrhea
- Obstruction or melena
What are the gross lesions of lymphoma?
- Moderately to marked enlarged lymph nodes
o Soft to firm
o Bulge on cut surface
o Homogenous pale tan to white
o Foci of necrosis or hemorrhage=common
o Often firmly attached (fibrosis) to surrounding tissue
What can lymphoma in other organs cause?
- Diffuse organomegaly
- Multiple tan nodules within organs
- Localized to generalized thickening of walls of tubular organs
o Uterus, intestine, stomach
What are the microscopic lesions of lymphoma?
- Neoplastic round cells EFFACE the normal architecture
- Uniform population of small lymphocytes with variable degree of:
o Anaplasia
o Mitosis
o Apoptosis
Canine lymphoma
- Most common canine hematopoietic neoplasia
- Usually middle aged to older animals
- 90% have normal leukogram
- 85% have multicentric lymphoma
o Lymph node involvement is common
o Medium to high grade tumours - *leukograms are usually normally
- No known cause OR viral association
Clinical signs of canine lymphoma
- Nonspecific OR absent at diagnosis
What are the other forms of canine lymphoma besides the multicentric?
- Alimentary
- Cutaneous
- Mediastinal (thymic)
- Miscellaneous
What does the alimentary form of canine lymphoma though to precede?
- Lymphoplasmacytic enteritis (IBD)
What can occasionally be seen in dogs with lymphomna?
- Hypercalcemia of malignancy
o Secretion of PTHrP by neoplastic cells
Feline lymphoma
- Most common malignant neoplasm in cats
- *leukemia an bone marrow involvement are common
- NO peripheral lymph node involvement
- SHORT clinical course
*associated with FeLV (10-20%)
What is the order of lymphoma types more likely in cats? (4 types)
- Alimentary
- Multicentric
- Thymic
- Miscellaneous
Feline lymphoma: short clinical course
- 75% affected are dead within 8 weeks of diagnosis if UNTREATED
Feline lymphoma is associated with FeLV
- 10-20% of cats with lymphoma are FeLV +
- FeLV is associated with MEDIASTINAL OR MULTICENTRIC T CELL LYMPHOMA
- Young cats!
Feline lymphoma clinical signs
- Non-specific
o Weight loss
o Anorexia
o Poor grooming habits - Referable to affected organ system
o Diarrhea
o Vomiting
o dyspnea
What are the multiple forms of bovine lymphoma?
- Enzootic bovine lymphoma
- Sporadic bovine lymphoma
Enzootic bovine lymphoma
- Adult cattle (5-8 years old)
- *bovine leukemia virus (oncogenic retrovirus)
o 30% of infected cattle: non-neoplastic persistent lymphocytosis
<5% of infected: lymphoma - *multicentric lymphoma of B cell origin
- More common in dairy cattle (management practices and average animal age)
- LIFELONG
How is bovine leukemia virus transmitted? (3)
- Arthropods
- Natural breeding
- Contaminated needles, dehorning and ear-tagging equipment
What is the target of bovine leukemia virus (BLV)?
- B-lymphocyte
- May cause lymphoma in sheep and goats
What are the 4 commonly affected sites with enzootic bovine lymphoma?
- Heart (R. atrium)
- Abomasum
- Uterus
- Vertebral canal
What are the clinical signs of enzootic bovine lymphoma?
- *Depend on organ involved
- Lymphadenopathy
- Diarrhea
- Vagal indigestion
- Congestive heart failure
- Posterior paresis/paralysis
Sporadic bovine lymphoma
- Not associated with a viral infection
- Affects young animals: 3 forms!
What are the 3 forms of sporadic bovine lymphoma?
- Calf form
- Juvenile form/thymic form
- Cutaneous form
Calf form of sporadic bovine lymphoma
- 3 to 6 months of age
- Symmetrical lymphadenopathy, often with
o Leukemia and bone marrow involvement - Kidney, liver, spleen
- *multicentric lymphoma
Juvenile form=thymic form of sporadic bovine lymphoma
- Young (<2 years) beef cattle
- Mediastinal lymphoma
What is the juvenile form/thymic form of sporadic bovine lymphoma characterized by?
- Large cranial thoracic/lower cervical masses
- Respiratory distress
- Weight loss in cattle less than 2 years of age
Cutaneous form of sporadic bovine lymphoma
- 2-3 year old cattle
- *Plagues or nodular, raised skin lesions often with ulceration
- Head, sides, perineum
- Lesions may wax and wane
- *survive 12-18 months
- DEEP ORGAN involvement indistinguishable from multicentric lymphoma
Porcine lymphoma
- Most common neoplasm of pigs
- Multicentric OR mediastinal
- Often <1 year old
- Females MORE than males
- Familial (hereditary) form
o Large white pigs
Equine lymphoma
- Lower incidence than dogs/cats
- Most common MALIGNANT neoplasm
- *multicentric is most common anatomic form
- Forms based on anatomic location
- T-cell rich, large B-cell lymphoma
- Wasting, anorexia, ventral edema, anemia, diarrhea
Equine lymphoma: forms based on anatomic location
- *Multicentric
- Cutaneous/subcutaneous
- Alimentary
- Abdominal
- Splenic
- Leukemic
In contrast to dogs, multicentric lymphoma in horses causes
- Masses in abdominal and thoracic cavity
- Also multiple subcutaneous nodules on trunk or limbs rather than GENREALIZED LYMPHADENOPATHY
