Paraneoplastic Syndromes Flashcards
(24 cards)
describe paraneoplastic syndrome
- remote effects of neoplastic disease usually due to tumor’s production of small molecules released into circulation causing effects at sites distant to tumor
- significant morbidity and mortality (as bad or worse than cancer itself)
- potentially complicate therapy but useful markers of disease
how does hypercalcemia cause PU/PD?
- increased calcium causes nephrogenic diabetes insipidus which leads to renal dysfunction
-nephrogenic DI: brain is making too much ADH (central) or kidneys not responding (peripheral, happening here) - inability to concentrate urine (PU)
- decreased renal blood filtration and GFR due to severe vasoconstriction
- degeneration, calcification, and necrosis of the urinary epithelium
describe the ddx for hypercalcemia (HOGS IN YARD) and which are most common in dogs
H: hyperparathyroidism
O: osteolysis (diffuse bone breakdown, not like as seen with primary bone tumor)
G: granulomatous disease
S: spurious
I: iatrogenic or idiopathic
N: neoplasia
Y: young
A: addison’s
R: renal disease:
D: vitamin D toxicity
most common in dogs: neoplasia!!!!!!!!!!
describe hypercalcemia of malignancy
- cancer = MOST COMMON CAUSE IN DOGS
-lymphoma!! #1 most common
-apocrine gland carcinoma of the anal sac!!
-multiple myeloma!!
-also: thyroid carcinoma, thymoma, squamous cell carcinoma, mammary gland tumors
how does cancer cause hypercalcemia?
- ectopic production of PTHrP
-most common!
-binds PTH receptors = release of calcium to body - ectopic production of PTH
- extensive boney lysis
- tumor production of PGE1/2
- tumor production of osteoclast-activating factor (OAF)
- rarely calcitriol or growth factors
describe diagnostics for hypercalcemia of malignancy
- confirm hypercalcemia with an ionized calcium FIRST
- search for neoplasia
-rectal
-LN cytology: EVEN if normal size!
-CXR
-AXR/AUS
-BMA (bone marrow aspirate) - hypercalcemia of malignancy panel
describe treatment for hypercalcemia of malignancy
- ID and treat the underlying cause!!
-lymphoma: chemo
-anal sac ACA: sx incision - can be a medical emergency esp if:
-serum calcium >18mg/dL and/or azotemia - symptomatic treatment:
-IV fluids: 0.9% NaCl
-AVOID USE OF STEROIDS UNTIL LSA IS CONFIRMED OR RULED OUT (could mask dx of lymphoma)
-bisphosphonates: pamidronate
-lasix: inhibits calcium reabsorption in the ascending loop of henle
describe causes of hypoglycemia
- insulinoma
- non-islet cell tumors
-hepatocellular carcinomas/hepatomas
-leiomyosarcomas/leiomyomas
-lymphoma
-hemangiosarcoma - lab error!
-false lower if delay in processing and given time to clot before spinning down - liver failure
- hypoadrenocorticisim
- starvation
- sepsis
how does cancer cause hypoglycemia? (6)
- secretion of excess insulin
- secretion of IGF-1 and IGF-2
- utilization of glucose by the tumor
- decreased glycogenolysis or gluconeogenesis
- upregulation of insulin receptors
- increased production of somatomedins
describe hypoglycemia
- signs can occur when the BG is <45-50mg/dl
- often related to the acuteness of hypoglycemia
- compensatory mechanisms to promote glycogenolysis and gluconeogenesis
-catecholamines
-glucocorticoids
-glucagon
-growth hormone
describe diagnostics for hypoglycemia
- measure insulin:glucose
-if glucose is low, insulin levels should be low and vice versa
-insulinoma: high insulin in the face of low glucose - AXR/AUS
- CXR
describe treatment for hypoglycemia
- ID and treat underlying cause!!
- small frequent feedings = more consistent blood sugar levels throughout the day
- prednisone
- 5% dextrose? will make insulin producing cells produce more insulin so tricky
- streptozotocin: chemo drug directly toxic to islet ells
- diazoxide
- somatostatin
describe ferrets insulinoma
- signalment: 2-3 years old
- clin signs:
-same as dogs
-ptyalism and nausea
-hindlimb weakness - bio behavior: rarely metastasize
- dx: same as dogs (AUS and paired glucose:insulin)
- treatment:
-surgical removal
-prednisone
-diazoxide: inhibits insulin release, stimulates gluconeogenesis and glycogenolysis and inhibits cellular uptake of glucose
how could you explain a hyperproteinemia with a hypoalbuminemia?
hyperglobulinemia!
-globulins = antibodies produced by plasma cells
-causes epistaxis by coating platelets and making them nonfunctional
describe hyperglobulinemia
- hyperviscosity syndrome:
-blood sludging in small blood vessels
-related to Ig type, size, shape, and concentration
- IgM > IgA > IgG - clinical signs:
-bleeding diathesis/predisposition
-retinopathies
-neurologic signs
-CHF - ddx:
-monoclonal: from the same plasma cells = indicates neoplastic process
-polyclonal: from a bunch of different plasma cells = more inflammatory or infectious process
-run a serum protein electrophoresis to figure out
how does hypergammaglobulinemia cause nephrotoxicity?
- bence-jones proteins
- tumor infiltration
- hypercalcemia
- amyloidosis
- decreased perfusion
describe monoclonal gammopathy
- increased production of monoclonal Ig
- causes:
-multiple myeloma!! (IgG or IgA)
-macroglobulinemia (IgM)
-lymphoproliferative disorders (B cell LSA)
-specific infectious diseases (ehrlichia, FIP)
-benign monoclonal gammopathy
describe multiple myeloma incidence and signalment
- <1% of all malignant neoplasma
-8% of all hematopoietic tumors
-3.6% of all prmary and secondary tumors affecting bone - affects older dogs (8-9 years old)
-GSD overrepresented
-no sex predilection - biologic behavior:
-systemic disease
-pathology arises from: increase in circulating immunoglobulins, organ infiltration of neoplastic cells, or both - sequelae:
-hyperviscosity syndrome
-renal disease
-bone disease
-hyeprcalcemia
-immunodeficiency
-cytopenias
-cardiac failure
describe clinical presentation of multiple myeloma
- manifestations of sequelae:
-epistaxis
-PU/PD
-retinal hemorrhage, detachment, blindness
-seizures
-ataxia, bone pain, lameness
-organomegaly - diagnostics: requires at least 2 of:
-bone maarrow plasmacytosis (>20%)
-osteolytic bone lesions
-monoclonal gammopathy
-bence-jones proteinuria
describe hypertrophic osteopathy
- periosteal proliferation shafts of long bones
- shifting leg lameness and warm, swollen limbs
- primary lung tumors, others
- treat underlying cause!!
describe anemia and cancer
- multiple possible cancers cause anemia:
-lymphoma
-HSA
-MCT
-sertoli cell tumors
-others
2, mechanisms include:
-anemia of chronic disease
-immune-mediated destruction
-blood loss
-myelophthisis
-hyperestrogenism
-pure red cell aplasia (FeLV)
- treatment:
-varies with etiology; ID and treat underlying cause
-blood transfusions
-AVOID USE OF STEROIDS UNTIL LSA IS CONFIRMED OR RULED OUT
-iron supplementation
describe thrombocytopenia and cancer
- multiple cancers:
-lymphoma
-HSA
-MCT
-sertoli cell - chemo induced
- mechanisms:
-immune mediated destruction
-sequestration
-myelopthisis/decreased production
-consumption: DIC
-utilization
-hyperestroginism - treatment:
-same as anemia
describe erythrocytosis and cancer
- uncommon
- causes include:
-increased epo production by tumor
-indirect increase in epo production due to renal hypoxia - associated with:
-renal tumors
-LSA
-liver tumors
-TVT - differentiate from polycythemia vera!
describe myasthenia gravis and cancer
thymoma
