Cytology

Question 0

What type of fluid samples are there?

Answer 0

bronchoalveolar lavage (BAL), transtracheal wash (TTW), pleural, peritoneal and synovial fluid, urine.

Question 1

What is cytology and what needs to be done well?

Answer 1

It is the examination and assessment of cells. It is a valuable diagnostic procedure if the smear prep is done correctly, any artefacts are not misinterpreted and the limitations compared to a biopsy are appreciated. e.g. cell architecture lost.

Question 2

What should fluid sample be placed in?

Answer 2

BAL/TTW, pleural, peritoneal and synovial fluid in EDTA tube (cytology) and a sterile tube ( for microbiology).
Preservation for smears- cytospin 50:50 fluid sample.
Urine in a universal sterile container, if cytology is required put in an EDTA tube.

Question 3

What are the two type of preparation techniques involved for testing urine?

Answer 3

Wet prep- will detect RBCs, WBCs, crystals, fats, bacteria etc.
Dried smears- from the EDTA sample are made for cytology if inflammation or abnormal cells are suspected as the wet prep is not suitable for this.

Question 4

What are touch imprints and what are they used for?

Answer 4

they are suitable for rapid diagnosis of some external lesions and excised tissues which may subsequently be examined by histopathology. Fresh blood and moisture is blotted off and then multiple impressions on a slide are made on a slide.

Question 5

What are scrapings used for?

Answer 5

collect more cells than touch imprints and is used for parasitology (demodex mite), the scalpel is used perpendicular to the skin. For conjunctiva- use a blunt spatula.

Question 6

What is a fine needle aspirate?

Answer 6

Suitable for cutaneous masses, internal masses and organs, lymph nodes etc. It avoids superficial contamination and will collect samples from deep in the tissue but there is a risk of missing the lesion all together.

Question 7

What can swabs be used for in cytology?

Answer 7

Used for tissues that cannot be easily reached e.g. vagina or fistulous tracts. They should be moistened in 0.9% NaCl, roll the swab don not slide it over the slide.

Question 8

What do techniques of smear preparation depend on an what are the two different types of preparation?

Answer 8

The cellularity and viscosity of the sample and presence of particulate material. Squash preparation and blood smear technique.

Question 9

What is squash preparation and what is it used for?

Answer 9

They are suitable for FNAs, viscous fluid samples, centrifuge samples, sample with flecks of cellular material and bone marrow aspirates. The sample is placed in the middle of the slide and spread with another slide that is at right angles to the other slide.

Question 10

How is a blood smear technique performed?

Answer 10

The sample is placed at one end of the slide, the spreader is just brought into contact with the drop and the spreader slide is then moved smoothly towards the opposite end of the slide.

Question 11

What are the stains used for cytology?

Answer 11

Diff-Quik- general cytology
Gram -ve bacteria (classified into g+ve and g-ve)
Ziehl-Neelsen- acid-fast bacteria e.g. mycobacteria

Question 12

What are the four steps for general assessment of cytology slides?

Answer 12

1) use low power and look over the whole smear for large structures.
2) then go to x20 and x40 to look at structures that may be missed under oil at x100.
3) To look in more detail, move to the x100 oil immersion gel.
4) The diagnosis may be made by a few cells at the edge- look all over the smear.

Question 13

What do we try to determine when looking at cytology?

Answer 13

1) the type of cells present
2) the degree of abnormality
3) the nature of the processes present.

Question 14

What are the three main categories of cell we look for in cytology?

Answer 14

1) epithelial- squamous, basal, glandular cells
2) mesenchymal- mainly CT: fibroblasts, osteoblasts.
3) round cell- lymphocytes, plasma cells etc.

Question 15

What are the cytological criteria for epithelial cells?

Answer 15

Large cell size, round to polygonal, high cellularity, lots of clusters.

Question 16

What are the cytological criteria for mesenchymal cells?

Answer 16

They are small to medium, spindle/stellate shaped, low cellularity and sometimes clumps.

Question 17

What are the cytological criteria of round cells?

Answer 17

Small to medium cells, round cell shape and usually high cellularity with no clumps.

Question 18

What differences do we look for in normal/hyperplastic tissue?

Answer 18

e.g. benign prostatic hyperplasia can show mild changes e.g. mild anisocytosis and slightly variable nucleus to cytoplasm (N:C) ratio.

Question 19

What does a cyst look like under the microscope?

Answer 19

It contains fluid and few cells. The fluid is low in protein (pale pink background). There are often reactive macrophages predominating. There may be evidence of haemorrhage (erythrocytes being engulfed) and blue/black haemosiderin granules in the macrophage cytoplasm- secondary inflammation. Can see plump mesenchymal cell.

Question 20

How do you classify inflammation?

Answer 20

By the number of inflammatory cells present.
Purulent- >85% neutrophils
Acute- >70% are neutrophils
Subacute- 50-70% neutrophils, 30-50% macrophages
Chronic- >50% macrophages
Granulomatous- predominance of macrophages and lymphocytes. Variable neutrophils and giant cells.
Eonsinophilic- predominance of eosinophils, >10%.

Question 21

What do you suspect if a neutrophil nuclei is swollen?

Answer 21

Suspect sepsis even if bacteria aren’t able to be seen.

Question 22

What does response to tissue injury look like under the microscope?

Answer 22

haemorrhage, fluid, fibrosis, necrotic material and inflammation. There are likely to be macrophages, possibly dark haemosiderin granules or showing erythrophagocytosis. Plump elongated fibroblasts are seen and necrosis creates a dirty background.

Question 23

What does hyperplasia look like?

Answer 23

may look normal or have higher N:C ratio and cytoplasmic basophilia may be increased.

Question 24

What does dysplasia look like?

Answer 24

It can mimic neoplasia and results from asynchronous maturation of different part of the cell e.g. immature nucleus in a mature cell.
neoplasia can look like dysplastic change- be careful.

Question 25

What criteria are used to determine whole cell malignancy?

Answer 25

Pleomarphism, anisocytosis, macrocytosis, hypercellularity (decreased cell adherence), disordered alignment of cells.

Question 26

What are the criteria of malignancy for the nucleus?

Answer 26

Anisokaryosis (variation in nuclear size), Macrokaryosis (diameter >10um), increased nucleus:cytoplasm ration (>1:2), multinucleation, increased mitotic figures, abnormal mitosis, atypical chromatin pattern, nuclear moulding.

Question 27

What are artefacts?

Answer 27

Nuclear streaking due to too much pressure when making the smear, haemorrhage due to sample collection (presence of platelets rather than erythrophagocytosis= present before sample collection), ultrasound and lubricant gel will go bright pink, starch from gloves will cause granules.