Clinical Pathology: Intro to Cytology, Cytology of Effusions Flashcards
What are the indications for cytology?
Characterise a detected abnormality-
mass/infiltrative lesion, organomegaly, ulcerative/exudative lesion, cavity or joint effusion
Staging of cancer- LN or internal organ metastasis
Diagnostic work-up of a patient with fever of unknown origin, hypercalcemia, monoclonal gammopathy
Bone marrow aspiration for investigation on non-regenerative anaemia, thrombocytopenia, bicytopenia, pancytopenia
What are the expectations for cytology?
- Highly dependent on the quality of the sample submitted
- Mostly the only option for fluids, the best option for BM and round cell tumours
- Detect inflammation and suspect or detect infection
- Detect neoplasia in most cases
- Differentiate between benign and malignant lesions and identity tumour type in many cases
What are histology and cytology?
What are the pros and cons of each?
What are the limitations of cytology?
Histology- the study of disease through evaluations of tissue sections
Cytology- the study of disease through the evaluations of cells
Pros v Cons
Cytology- less invasive, less time, lower cost, in house, excellent cellular assessment, can assess fluids
Histology- can use immunostains, most representative and shows tissue architecture
Cytology limitations-
Sometimes difficult to achieve a final diagnosis on a cytology sample even for an experienced clinical pathologist as a tissue architecture cannot be assessed
It May not be representative or inadequate quality
We can look as slides straight away but may need external lab
What are the sources of cells usef for cytology?
How are cells collected?
Sources-
tissue- palpable lesion, internal organs, LN, BM
Fluids- body fluids- abdominal/thoracic effusions, joint fluid, cerebrospinal fluid, lavage and wash fluids
Body fluids/discharges
Collection-
Fine needle biopsy- sampling or aspiration
Touch imprints or scrapes
Swabs
Aspiration of body fluids- cavitary, synovial, bile, urine
Administration and collection of body fluids- tracheal was, BAL
How can a cytology sample be improved?
Increase cellular yield-
take several aspirates, several smears
stain one to determine if cellular/representitive
submit all slides
Increase diagnostic quality-
apply a light tough to prevent smashing of cells
too thin, too thick
Minimise haemodilution- be quick and use non-aspiration first
How are cytology slides prepared?
Depends on whats being sampled
Masses and organs- squash
Biopsies- imprint
Fluids- smear
How are cytology slides processed?
Describe the approach to the cytology slide
Can be stained in house for quick evaluation
Recommend for checking the quality/cellularity of the sample
For surgical emergencies
Approach-
be consistent- always use the same order
be thorough- scan the entire slide and all stained slides
don’t jump straight to high power
What should be assessed by the naked eye, low power and high and very high power?
Nakey eye- labelling, staining and distribution assessment
Low power- 4-10x
A quick scan for quality, cell preservation and distribution (chose the sweet spot)
Scan for the big stuff (larvae, fungi, eggs)
Preliminary identification of cell types and their arrangement
Assess background
Artefacts- ruptured cells, poorly stained, formalin, ultrasound gel
High power- 40x, 50x
more accurate identification of cell types
Inflammatory, tissue cells or matrix
Classify inflammation- the type to help determine the aetiology
Identify cell tissue- normal or abnormal
Very high power- further characterisation of nuclear-cytoplasmic detail
Better ID od microorganisms
What are the following types of inflammation?
A- Histiocytic
B- Pyogranulomatous
C- Eosinophilic
D- Lympho-plasmacytic
E- Neutrophilic (suppurative)
What are examples of cavitatory fluid?
What is their purpose of them?
What are they composed of?
Peritoneal, pleural and pericardial cavity fluids- lined by mesothelium
Contain scant serous fluid that facilitates movement
An ultrafiltrate of blood- low cellularity, low total protein
Small animals have too little fluid to be sampled
What does the volume of fluid in body cavities depend upon
What is an effusion?
Depends on the equilibrium between:
The hydrostatic pressure of blood
Oncotic pressure of blood
Permeability of vessels
Effusion-
Any accumulation of fluid in a body cavity, indicative of a pathological process
How are effusions analysed?
Gross appearance- colour, turbidity
Odour
Cell counts and total protein
Microscopic examination
Biochemistry depending on case
How are effusions classified?
What is transudate and exudate?
Classified based on protein, cell count and cytology
Transudate- effusions are usually caused by imbalances of hydrostatic and/or oncotic pressure
Exudate- effusion is usually caused by increased vascular permeability due to inflammation
Classified based on aetiology and composition-
Haemorrhagic, Chylous, Pseudochylous, Neoplastic
What are haemorrhagic effusions caused by?
Heavily blood stained
Caused by true cavity haemorrhage-
vessel disruption, bleeding tumour, coagulopathy, trauma, lung lobe torsion
The fluid does not clot, and supernatant often does not haemolyse
Microscropy- erythrophagocytosis, no platelets
Iatrogenic blood contamination-
Initially clear then bloody/vice-versa
Should form clot, supernatant clear, can see platelets
Splenic tap
How is abdominal haemorrhage investigated with cytology?
Coagulation profile/haematology
Ultrasound abdomen to check for masses
Look for neoplastic cells
What is chyle?
Chylomicron-rich lymph
Chylomicrons-
TG- rich lipoproteins absorbed from the intestine
Transport of dietary lipid
Enter lymphatics, then blood via thoracic duct
Big so make fluid opaque- milky
How do chylous effusions appear?
What is the protein amount?
What is their cell count?
What causes them?
Milky fluid- white opaque
Protein often >25g/l
Cell count variable- cytology mainly lymphocytes but can be mixed, neutrophils increase with chronicity
Formed due to lymphatic drainage impairment of lymphatic leakage
Causes-
Heart disease
Trauma/surgery
Neoplasia
Idiopathic
Chyloabdomen- rare
What is pseudochyle?
Looks similar grossly to chyle
Not high in triglycerides
White colour due to cell debris, protein and cholesterol
Uncommon
How do (low protein) transudates appear?
How much protein is in them?
What cells are present?
What causes them?
Clear, colourless
Protein <25g/l
Cell count low- <1.5x10^9
Few, mainly monocytes and macrophages
Duse to decreased oncotic pressure to due to low serum protein
Causes-
Severe hypoalbuminaemia- protein-losing enteropathy/nephropathy, liver disease
Portal hypertension
Over hydration
Cardiac failure
Thrombi in major vessles
What is modified transudate?
How does it appear?
How much protein?
What is the cytology?
What causes it?
Modified- more protein and cells than pure but less then exudate
Colourless to amber/pink- clear
Protein >25g/l cell count <5 x 10^9
Cytology- low cellularity, mixed populations of cells, more neutrophils than a transudate
Caused by increased hydrostatic pressure
Increased IV hydrostatic pressure in liver or lung
CHF
Thrombi or neoplasia
Non-exfoliating neoplasia
Lung lobe/splenic torsion
Occasionally FIP
How do exudates appear and how are they characterised?
Turbid
Yellow/brown/bloody
High nucleated cell count
High protein
Mostly neutrophils- inflammation
Due to increased vessel permeability
Septic or non septic
How do septic and non-septic exudates appear?
What causes septic and non-septic?
Septic- intracellular organisms (not always visible), absence of organisms does not rule out sepsis, often degenerate neutrophils
Non-septic- non-degenerate neutrophils, lower number of hypersegmented neutrophils and pyknotic cells
Causes of septic-
penetrating wound, foreign body, GI perforation, Haematogenous route
less commonly- gall bladder rupture, pancreatitis, rupture of pyo, abscess in liver
Causes of non-septic
Ruptured gall bladder/urinary bladder, necrotic tumour, pancreatitis, FIP
How does FIP exudate differ?
What causes bile peritonitis?
How can a ruptured bladder be diagnosed?
FIP-
virus- vasculitis
yellow sticky fluid, high protein (froths), moderate cellularity
Globulin: albumin ratio A:G low in FIP (>0.8 not FIP)
Mainly neutrophils
Bile peritonitis-
ruptured gall bladder/duct- trauma/obstruction
Fluid often green ± secondary infection
Neutrophils, macrophages, bilirubin higher then plasma
Ruptured Bladder-
conc creatine > conc creatine plasma
starts as transudate- urine it irritant- becomes exudate
Why do neoplasms cause effusions?
What are the pitfalls?
- Compression of blood vessels and lymphatics
- Increased vessel permeability
- Inflammation
- Necrosis
- Haemorrhage
- Cell exfoliation
- Lymphoma, adenocarcinoma, mesothelioma
Pitfalls-
mesothelial cells found in all effusions
Shed off pleura/peritoneum
Become reactive
Look like tumor cells
How do reactive mesothelial cells of the pleura appear?
Eosinophilic fringe or brush border
May be multinucleated
May contain prominent multiple nucleoli or variable shapes or sizes
May phagocytose cells and particulate matter
What are the indications for arthrocentesis?
- Joint disease of unknown aetiology
- Disease in multiple joints
- Suspected infectious arthritis
- Pyrexia of unknown origin
- Monitoring therapeutic response
How does synovial fluid normally appear and how can it vary?
- Normal- pale yellow
- Inflammation- yellow turbid
- Haemarthrosis- uniformly bloody
- Contamination- clear then bloody
Normal- clear, pale yellow, very viscous, hypocellular, protein background
Trauma- grossly red, low viscosity due to effusion, red cells, some neutrophils
Osteoarthritis- cellularity normal or mildly increased, predominantly mononuclear, can see osteoclasts
Inflammatory arthropathy- viscosity reduced, cellularity increased, increased cells- degen neutrophils,
Septic arthritis- usually monoarticular, penetrating wound, haematogenous spread, often we do not see bacteria
How should synovial fluid sampled be handled?
Make smear immediately
Note viscocity
Collect into EDTA and sterile plain tube
Always send fresh smear with sample
What further investigations can be done for transudate and modified transudate?
Transudate-
Biochem- plasma serum
Urinalysis
Imaging
Look for GI/Renal disease
Modified transudate-
Auscultation, echocardiography
Liver enzymes, bile acids
Drain and re-Xray (mass/tumour)
