Pathology of the Hematopoietic System, Pt. 2 Flashcards
What is multiple myeloma? What does it tend to cause?
malignant tumor of plasma cell origin arising from the bone marrow
neoplastic (clonal) plasma cells secrete immunoglobin leading to hypergammaglobinemia
What are the 3 specific diagnostic criteria of multiple myeloma?
- neoplastic plasma cells in the bone marrow
- lytic bone lesions seen on radiographs
- presence of clonal immunoglobulin paraproteins in the serum (monoclonal gammopathy) or urine (Bence-Jones protein)
How does multiple myeloma present grossly? Histologically?
GROSS: pale pink to dark red gelatinous masses replace bone marrow, typically with multiple masses
HISTO: sheets of neoplastic plasma cells
What is the anatomy of lymph nodes like? What cells are present at each place?
- outer cortex follicles contain B cells
- inner cortex paracortex contain T cells
- medulla mostly contains B cells and macrophages
What are the 2 major functions of lymph nodes?
- filtration of lymph
- launch immune response
How does lymph flow through a lymph node? In what species is this different?
afferent lymphatics —> subcapsular sinuses —> trabecular sinuses —> medullary sinuses —> efferent lymphatics —> thoracic duct
reverse in pigs - cortex = inner; medulla = outer
What are the 3 major reaction patterns seen in lymph nodes?
- SMALL LN - lymphoid atrophy, LN degeneration, LN hypoplasia
- ENLARGED LN - lymphoid hyperplasia +/- drainage, lymphadenitis, metastatic neoplasia, primary neoplasia (lymphoma)
- DISCOLORATION/PIGMENT
What type of reaction is lymphoid hyperplasia? What does this entail?
immunological reaction = response to some type of antigen
lymph nodes are working to drain the site of local infection or vaccination
Lymphoid hyperplasia:
enlarged follicles causing increased lymphocyte production
Lymphoid hyperplasia, histology:
germinal center is prominent
What 4 bacteria commonly cause suppurative lymphadenitis?
- Streptococcus equi subsp. equi (horse)
- Streptococcus porcinus (pig)
- Corynebacterium pseudotuberculosis (sheep, goats)
- Trueperella pyogenes (cattle, sheep)
What 3 microorganisms cause granulomatous lymphadenitis?
- BACTERIA: Mycobacterium bovis, Mycobacterium avium subsp. paratuberculosis (ruminants); Rhodococcus equi (horse)
- VIRUSES: porcine circovirus 2, feline infectious peritonitis
- FUNGI: Blastomyces dermatitidis, Cryptococcus neoformans, Histoplasma capsulatum
Equine retropharyngeal LN:
- MDx: suppurative lymphadenitis
- etiology: Streptococcus equi subsp. equi
- condition: Strangles
What is bastard strangles?
metastatic strangles where the Streptococcus equi subsp. equi is able to hematogenously migrate to internal organs
(fibrinous deposits on lung)
Ovine LN:
- MDx: caseous lymphadenitis
- etiology: Corynebacterium pseudotuberculosis
- AKA: onion skin
Bovine mesenteric LN:
- MDx: granulomatous lymphadenitis
- etiology: Mycobacterium bovis
What is Rhodococcus equi? What are the 2 most common forms of its disease?
common, facultative intracellular Gram-positive bacterium that typically infects foals 1-6 months
- RESPIRATORY: pyogranulomatous bronchopneumonia
- ENTERIC: ulcerative enterocolitis, caseous/granulomatous lymphadenitis
What primary and metastatic neoplasias are commonly found in the lymph nodes?
PRIMARY: lymphoma, plasma cell tumor, histiocytic neoplasms
METASTATIC: carcinomas, melanomas, mast cell tumors
Metastatic oral melanoma, dog:
pigmented, white tissue expands lymph nodes
What is hemosiderosis?
brownish discoloration observed in lymph nodes draining areas of hemorrhage
What causes anthracosis? When is this a common finding?
carbon particles retained in macrophages, mainly located in the medullary cords, causing the medulla of lymph nodes to appear black
common in bronchial lymph nodes of dogs and humans living in polluted urban areas
Anthracosis, cow:
histopathology necessary to differentiate draining pigment from melanoma
What is the structure of the red pulp of the spleen? What 3 functions does it have?
sinusoids/vascular spaces and splenic cord
- filters blood - removes foreign materials (phagocytosis)
- RBC storage
- hematopoiesis (EMH)
Where in the white pulp is each white blood cell found? What is the overall function of the white pulp?
T CELLS = periarterial lymphatic sheaths (PALS)
B CELLS = lymphoid nodules
MACROPHAGES = marginal zone
- immune response
What are the 2 major reaction patterns seen in the spleen?
- diffuse splenomegaly - bloody vs. meaty
- nodular spleen - bloody vs. meaty
(meaty = cells!)
What are 3 causes of diffuse splenomegaly with a bloody consistency (bloody spleen)?
- congestions - torsion, barbiturate euthanasia
- septicemia - anthrax
- acute hemolytic anemia