Basic Principles of Cytological Examination

Question 1

What do you expect from cytology and its limitations? (7)

Answer 1

• Can be an effective tool for the diagnosis of neoplasia (non-invasive sample acquisition, low cost, short turnaround time) + inflammation.
• Outcome of the cytological examination will depend on the quality of the submitted smears (cellularity, cell preservation, representative sample e.g. lesion).
• Not possible to appreciate tissue architecture which may be important for a reliable diagnosis - may be more than one process going.
• Presence of concurrent disease processes (e.g. inflammation + neoplasia, necrosis + neoplasia) is reducing the degree of confidence in the cytological interpretation.
• Different processes which can appear indistinguishable on cytology (e.g. fibroplasia (benign, response to tissue damage) and low-grade spindle cell neoplasia).
• Well-differentiated neoplasms may appear indistinguishable from normal tissue on cytology.
• Presence or absence of cytological criteria of malignancy is not necessarily an indication of the potential future biological behaviour of a neoplasm e.g. mammary tumours - don’t know if malignant or benign.

Question 2

Material examined (cytology report) =

Answer 2

•E.g. “Three smears from a s/c mass located in the lumbar area are examined”.

Question 3

Cytological description (cytology report) = (5)

Answer 3

Observations and descriptions:
•Cellularity and cell preservation (diagnostic quality).
•Background (e.g. proteinaceous, amount of blood, foreign material, etc.).
•Cell population/s present (tissue-derived cells, inflammatory cells).
•Detailed description of the cells of interest - cytological criteria of malignancy and degree of each change (mild, moderate, marked).
•Presence of organisms.

Question 4

Interpretation (cytological report) = (3)

Answer 4

• E.g. carcinoma - frequently use moderators such as “consistent with”, “suspicious of” to indicate the degree of uncertainty).
• Diagnosis.
• E.g. Malignant tumour w/ epithelial origin.

Question 5

Comment (cytological report) = (4)

Answer 5

• Give further information e.g. prognosis.
• Explain why diagnosis was made (subjective opinion).
• What is compromising the degree of certainty.
• Frequently propose further testing to assist diagnosis.

Question 6

Cytology = (7)

Answer 6

• Examination of individual cells.
• No information on tissue architecture, tissue/lymphatic invasiveness, etc.
• High intracellular (e.g. nuclear, nucleolar) detail.
• Small organisms (e.g. bacteria) are more easily identified even in low numbers.
• Fast turnaround times.
• Lower cost.
• Non-invasive sample collection.

Question 7

Histopathology = (7)

Answer 7

• Examination of tissue sections.
• Good preservation of tissue architecture, more reliable for assessing the potential future behaviour of many tumours.
• Low intracellular detail.
• Small organisms (e.g. bacteria) are difficult to identify if present in.
• Slower turnaround times.
• Higher cost.
• More invasive sample collection.

Question 8

What are Immunohistochemistry (IHC) and immunocytochemistry (ICC)? (Slide 5)

Answer 8

•The use of colour-labelled antibodies to identify certain cell markers on histopathology slides (immunohistochemistry), or cytology smears (immunocytochemistry).

Question 9

What can the use of antibodies help us do? (3)

Answer 9

• Identify the exact cell type where this is not clear on routine staining (e.g. round cell tumours) - surface/inside cells. •Recognise a sub-group within a cell type (e.g. differentiate T-lymphocytes (positive for CD3 antibodies) and B-lymphocytes (positive for CD21 antibodies) within a lymphoid cell population).
• Identify certain properties of tissues (e.g. cell proliferation markers such as Ki-67 in mast cell tumours - low or high grade)