Exam 3 - Polycythemia, Splenic Disorders, & Lymphadenopathies Flashcards
what is relative polycythemia?
artificial increase in Hct but a normal RBC count – increase in Hct from loss of plasma volume
seen with dehydration & exudative wounds (burns), may seen increased Na, TS, & pre-renal azotemia
what is absolute polycythemia?
true increase in Hct/PCV – classified as primary or secondary
what values define polycythemia in dogs? cats?
dogs – PCV >55%, hemoglobin > 18 g/dL
cats - >50%, hemoglobin > 14 g/dL
how is primary polycythemia defined?
bone marrow is producing too much – NOT driven by EPO
how is secondary polycythemia defined?
driven by increased EPO – either appropriate or inappropriate
what are the end target organs in polycythemia & how are they affected?
CNS – ataxia, mentation changes, & seizures
ocular - +/- retinal hemorrhage, retinal detachment, blindness
nasal – epistaxis
what does ‘sludgy’ blood indicate?
hyperviscosity
what clinical signs are associated with polycythemia?
sludgy blood, hypercoagulability, PU/PD, & caudal cyanosis (right to left shunt)
what is the purpose of phlebotomy in patients with polycythemia?
removing a certain % of blood volume to decrease hyperviscosity
what is the target PCVs when performing a phlebotomy?
dogs – 55%
cats – 50%
goal is to remove 10-20 ml/kg
T/F: phlebotomy may not be ideal for all cases, but it should be performed in patients exhibiting clinical signs of polycythemia
true
what is the mechanism of primary absolute polycythemia?
marrow is producing too much erythrocyte lineage
peripheral EPO levels are low
bone marrow shows same as if EPO levels are high
can’t use bone marrow to differentiate primary from secondary
T/F: bone marrow examination can be used to differentiate primary from secondary polycythemia
false - not ideal
what is the mechanism of appropriate secondary polycythemia?
primary trigger – body needs more PaO2 (hypoxemia), such as pulmonary disease, increased altitude, or right to left cardiac shunting
T/F: for appropriate secondary polycythemia, the most important therapy long-term is phlebotomy
false – find the underlying cause & treat that
what is the mechanism of inappropriate secondary polycythemia?
secondary source of EPO being produced independent of O2 need – normal PaO2 – diseases such as renal EPO producing tumor, or rare other tumors such as nasal
how is secondary inappropriate polycythemia treated?
must find mass & if possible, & remove
what diagnostics are typically used for polycythemia?
thoracic & abdominal imaging – tumor hunt!!!
history/clinical signs are very important!!!
PaO2 levels, history of respiratory or cardiac disease
EPO levels are ideal – but very hard to do & often unavailable
what is the therapy used for polycythemia?
find the underlying cause!!!!
phlebotomize as necessary & pharmacologic management
what is the mechanism of action of hydroxyurea for patients with polycythemia?
erythropoiesis suppressant
why is clopidogrel used for patients with polycythemia?
anti-coagulant
what are the 3 general functions of the spleen?
- immune system – main defense against intracellular & cell surface pathogens affecting RBC/WBC, cleans up expired RBC
- reservoir – platelets, lymphocytes, & RBCs, extramedullary hematopoiesis
- iron metabolism
what happens with splenic contraction?
increases RBC – can see with bone marrow failure, anemia, & contraction can increase PCV substantially
why is the spleen important for iron metabolism?
storage, metabolism, & delivery of iron to the bone marrow
splenectomized patients have low iron – but other cells eventually take over this process
what specific organisms do we care about in relation to the spleen?
babesia, mycoplasma, & rickettsial bugs
what 4 non-neoplastic splenic diseases are covered?
- splenomegaly – not always pathologic, can see with sedation
- infectious – fungal, exfoliates well
- hypersplenism – rare benign disorder
- splenic torsion in dogs – surgical emergency, more common in deep chested breeds
what is the most common non-neoplastic splenic disease?
splenomegaly
what is the most common neoplastic splenic disorder?
hemangiosarcoma - often cavitated, aspiration not high yield
what are the most common locations of hemangiosarcoma tumors?
right atrium, liver, & spleen
how is hemangiosarcoma treated?
recommended splenectomy
what is hypersplenism?
rare, benign disorder
sequestration of RBC (associated with increased RBC turnover)
no medical management
what is the classic appearance of splenic lymphoma?
chicken wire or leopard spot appearance
how is lymphoma of the spleen diagnosed?
FNA of liver or spleen is typically high yield
how are mast cell tumors of the spleen diagnosed?
FNA of liver or spleen is typically high yield
what dog breeds are predisposed to histiocytic sarcomas?
bernese mountain dogs & flat coated retrievers
what are some contraindications to splenic aspiration?
suspect hemangiosarcoma/hemangioma
thrombocytopenia < 60,000 or coagulopathy suspected
what 4 diseases are covered for neoplastic splenic disorders?
- hemangiosarcoma
- lymphoma
- mast cell tumor
- histiocytic sarcoma
what are some clinical signs associated with splenic disease?
if severe – collapse, anorexia, fluid wave, vomiting, pale MM, hemoabdomen
what is the usual cause of a hemoabdomen?
ruptured splenic or hepatic mass
how is hemoabdomen diagnosed?
abdominocentesis/pericardiocentesis
blood that has pooled in the abdominal cavity or around the pericardium should NOT clot because the clotting factors are used up. what does it mean if you have blood clots?
active bleeding present or you hit an organ – liver, spleen, or heart
what is the minimum database for splenic disease?
CBC - +/- anemia, thrombocytopenia due to sequestration
chemistry – WNL or increased globulins
what may be seen on ultrasound on an animal with splenic disease?
splenomegaly, mottled or abnormal echotexture, masses, or splenic lymphadenopathy
what may be seen on radiographs on an animal with splenic disease?
metastasis, heart base mass
what is the premise of NuQ testing for splenic disease?
screens for increased amounts of DNA nucleosomes – NuQ increased a lot with malignancy
good chance between differentiating between benign vs. malignant splenic masses & lymphoma
when would you run a NuQ test?
screen breeds at risk, splenic mass prior to surgery if the owner is on the fence
what is the therapy for hypersplenism & splenic torsion?
surgery
what is the therapy for splenic neoplasia?
remove mass ideally – if infiltrated other organs, may need to FNA to look for disseminated disease - lymphoma, MCT, & histiocytic sarcoma
if EMHA or infectious splenic disease is present, how do you diagnose it? what about therapy?
diagnose via FNA, EIA< or serology
IMHA cases – treat IMHA
some refractory cases require splenectomy
T/F: you can’t differentiate between benign & malignant neoplasia of the spleen using ultrasound alone
true - must do histopath
what are the etiologies of reactive/benign lymphadenopathy & malignant lymphadenopathy?
- reactive/benign – anything antigenic to the immune system, infectious diseases causing a reactive lymphadenopathy or infection in the lymph node
- malignancies – primary neoplasia such as lymphoma or mast cell tumor, or metastasis
hilar lymphadenopathy is often indicative of what?
very indicative of fungal disease
what should you do if there is sternal lymphadenopathy?
sternal lymph nodes drain the abdomen – so only if it’s enlarged, look at the abdomen
if you see sub lumbar lymphadenopathy, what is this often indicative of?
prostatic disease or neoplasia
how can you differentiate between reactive & neoplastic lymph nodes on FNAs?
normal lymph node has mostly small lymphocytes
neoplastic nodes – look for mitotic figures & other criteria or malignancy
FNAs of neoplastic nodes can be diagnostic for what round cell tumor types?
lymphoma, nasal adenocarcinoma, melanoma, & mast cell tumor
what are the criteria of malignancy for FNAs of lymph nodes?
- anisocytosis
- anisokaryosis
- mitotic figures
- increased N:C ratio
- vacuolization
- multinucleated cells
what 2 atypical agents cause disease in dogs & cats causing large, sometimes hemorrhagic & purulent discharge from lymph nodes that is zoonotic & requires a biopsy to diagnose?
mycobacterium & cornyebacterium tuberculosis
why use flow cytometry for lymph node aspirates?
differentiate between reactive & neoplastic nodes – ship immediately!!!
T/F: lymphoma is often very easy to diagnose if lymphadenopathy is present
true
T/F: NuQ vet cancer test is helpful in screening at risk breeds for lymphoma
true
T/F: certain atypical bacterial infections can cause marked lymphadenopathy, and may require certain precautions & biopsy
true
where should you palpate in an animal with lymphadenopathy? why?
axillary & sub-inguinal are abnormal to be able to palpate!!!!
lymphadenopathy is non-specific but gives you clues
