Cytology & Effusions Flashcards
What are the 3 major types of samples used for cytology?
- FNA (22G needle and 5cc syringe) and impression smears
- washes - prostatic, transtracheal
- fluids - peritoneal, pericardial, pleural, synovial, CSF, bronchoalveolar lavage, urine
What are the pros to running cytology?
- minimally invasive
- fast, simple, inexpensive
- better cellular detail than histopathology
- can observe infectious organisms
What are some cons to running cytology?
- cannot evaluate tissue architecture
- poorly exfoliating lesions, like sarcomas, are difficult to observe
- can rupture cells
- can’t always be used to make a diagnosis
- difficult to differentiate reactive mesenchymal cells from neoplastic cells
What are the 3 major components of a cytological evaluation?
- overall cellularity - high vs. low (low cellularity samples make interpretation difficult)
- cell components/types - uniform populations vs. mixed
- background components - blood, proteinaceous material, organisms
(best to send organ aspirates and bone marrows to pathologists)
What is the first approach to evaluating a cytology sample?
scan the slide at low magnification (10x) and find cellular area where cells are well spread out and intact
- where the appearance of nuclei and cytoplasm of individual cells can be evaluated
What is done on cytology evaluations at high magnification (50x, 100x oil)?
characterizing cells - normally found in the location of the sample?
- types of inflammatory cells
- organisms presence
- non-inflammatory cells: epithelial, mesenchymal, round
- do non-inflammatory cells exhibit criteria of malignancy
How are inflammatory lesions classified?
- suppurative = neutrophils
- mononuclear = lymphocytes, plasma cells, macrophages
- histiocytic/granulomatous = macrophages
- pyogranulomatous = neutrophils + macrophages
- eosinophilic
- lymphoplasmacytic = lymphocytes + plasma cells
- mixed
What is evaluated on suppurative inflammation?
neutrophil morphology —> degeneracy (larger than normal with distended vacuolated cytoplasm and a slightly swollen enlarged nucleus)
- if yes, search for bacteria
What infectious cause of suppurative inflammation? What if an eosinophilic component is also seen?
bacterial infection —> especially if there are degenerate neutrophils (septic suppurative)
parasitic or allergic component to inflammatory response
What are 4 possible non-inflammatory causes of suppurative inflammation?
- severe irritants/chemicals - uroperitoneum, bile peritonitis
- immune-mediated inflammation
- trauma
- ruptured follicular/epidermal cysts
What are 3 infectious causes of histiocytic/granulomatous inflammation?
MACROPHAGES
- protozoa - Leishmania, Toxoplasma
- atypical bacteria - Mycobacteria, Nocardia, Actinomyces
- fungi - Histoplasma, Blastomyces, Cryptococcus, Coccidioides
When is fungal infection especially indicated with histiocytic/granulomatous inflammation?
if epithelioid macrophages and/or multinucleated giant cells are found
What are 3 non-infectious causes of histiocytic/granulomatous inflammation?
- foreign bodies/materials - plants (grass awns), vaccine adjuvants
- acral lick dermatitis (lick granuloma)
- late stage chronic/resolving inflammation
What makes up pyogranulomatous inflammation? What are the 3 most common causes?
50-70% neutrophils, 30-50% mononuclear cells (macrophages, multinucleated giant cells, lymphocytes, plasma cells, mast cells)
- foreign body
- fungal infections
- chronic/resolving suppurative inflammation
What are 2 infectious causes of eosinophilic inflammation?
- parasites: Dracunculiasis, Demodicosis, Dirofilaria, Dermatophytes
- oomycosis and algal organisms: Pythium, Prototheca
What is commonly also seen with non-infectious eosinophilic inflammation? What are 3 common causes?
mast cells and basophils
- eosinophilic plaque/granuloma
- flea bite or food allergies, atopy
- arthropod bite reaction
What are the 3 categories of neoplasia? Why is cytological criteria evaluated?
- epithelial
- mesenchymal
- round
detects criteria of malignancy to determine if the neoplasia is benign or malignant (NOT reliable for round cell tumors)
What are the 6 criteria for malignancy?
- anisocytosis - variation in cell size between cells of the same origin
- anisokaryosis - variation in nuclear size
- immature chromatin
- multinucleation
- abnormal mitotic figures
- nucleolar changes - enlarged, prominent, multiple, variably shaped nucleoli
What are the 3 main characteristics of epithelial cell tumors?
- tightly cohesive clusters
- polygonal to round
- distinct intercellular junctions
What are the 6 categories of round cell tumors?
- plasma cell
- histiocytoma
- lymphoma
- transmissible venereal tumors
- mast cell tumors
- melanoma
What are the 4 major characteristics of round cell tumors?
- exfoliate well, samples are highly cellular
- round shape/borders
- can be in clusters or individually distributed
- criteria of malignancy are not reliable
What are the 3 major characteristics of mesenchymal tumors?
- exfoliate poorly, better suited for histopathology
- distributed both in clusters and individually
- wispy, attenuated to stellate, abundant cytoplasm
What are the 4 basic parts to fluid analysis?
- color, clarity
- cell count
- total protein
- cytological evaluation - differential cell count, cell morphology, organisms
additional tests may be indicated
How should fluids be collected? What if they’re being cultured? How are they sent out?
in an EDTA (purple top) tube to prevent clotting
collect a separate aliquot from into a red top tube, since EDTA is bacteriostatic and can cause false negatives
since the fluid will likely not be process within 2 hours, make direct smears and send a purple top AND a red top tube to the lab
How does color of the fluid give indications of etiology? What does turbidity indicate?
- clear to pale yellow = normal
- red = iatrogenic or true hemorrhage
- yellow to dark green = bile
- bright yellow = urine
increased cellularity, bacteria, fibrin, lipids, ingesta from GI rupture or accidental enterocentesis
What are the 2 ways that protein counts are done on fludis?
- refractometry: peritoneal, pericardial, pleural, synovial
- biochemical: CSF
What are the 2 major cell counts done on fluids?
- total nucleated cell count via automated hematology analyzer
- WBC differential count obtained by counting leukocytes on a stained cytology slide
How are effusions classified? What are the 3 types?
total nucleated cell count and protein concentration
- pure transudate = < 2.5 g/dL protein, < 1500 TNCC/µL
- exudate = > 2.5 g/dL protein, > 5000 TNCC/µL
- modified transudate = somewhere in between
How do true hemorrhage and blood contamination in effusions compare?
TRUE HEMORRHAGE = erythrophagocytosis (macrophages contain RBCs), hemosiderin-laden macrophages, supurnatent will be pink, yellow, or orange (unless acute), PCV and protein close to peripheral blood values
CONTAMINATION = platelets, absence of erythrophagocytosis, protein and cell counts will be less than peripheral blood, clear supernatant
True hemorrhage, effusion:
What are traumatic and non-traumatic causes of hemorrhagic effusions?
TRAUMATIC = blunt or penetrating trauma (HBC, gunshot wounds)
NON-TRAUMATIC = malignant neoplasia (HSA), hematoma, organ torsion, rodenticide toxicosis, coagulopathies
What is seen in chylous effusion? What causes it? What levels are measured and compared to serum for diagnosis?
- small lymphocytes with acute with incrasing numbers of neutrophils and macrophages over time
- chylomicrons —> white-pink, opaque, no clearing with centrifugation
modified transudate from leakage of thoracic duct or other lymphatics
triglyceride level in effusion will be 2-3x that in the serum
What are some causes of chylous effusion in the pleural cavity?
- cardiovascular disease
- neoplasia (lymphoma, thymoma)
- heartworm disease
- diaphragmatic disease
- lung lobe torsion
- fungal granulomas
- idiopathic
What are some causes of chylous effusion in the peritoneal cavity?
- cardiovascular disease
- FIP
- neoplasia
- steatitis
- biliary cirrhosis
- lymphatic rupture or leakage
How are biochemical tests used on fluids?
confirm or differentiate between causes of an effusion by comparing the fluid analyte level to the serum or plasma
What 2 biochemical analytes are used to diagnose septic effusions?
- GLUCOSE: fluid glucose will be less than serum glucose because bacteria consume glucose to survive
- LACTATE: fluid lactate will be higher than blood concentrations (product of respiration)
What biochemical analytes are used to diagnose chylous, bilious, and uroperitoneal effusions?
CHYLOUS - triglycerides in fluid > 3x serum triglycerides
BILIOUS - fluid bilirubin > serum bilirubin
UROPERITONEUM - fluid creatinine and potassium > 2x serum levels
