Cytology: FNAC and concentration techniques

28 Kerala PSC Lab Technician Gr II practice questions on Cytology: FNAC and concentration techniques, part of Pathology. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

1. Question 1 · Easy

   How is a cell block made in cytology?

   1. ASpinning cells directly onto a slide
   2. BGrowing the cells in a culture flask
   3. CProcessing the fluid sediment like tissue
   4. DFreezing fresh tissue in a cryostat

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   Answer: C · Processing the fluid sediment like tissue

   The sediment of a centrifuged fluid or a needle rinse is fixed, held together (for example with plasma and thrombin or agar) and processed into paraffin like a small biopsy. Many sections can then be cut for H&E, special stains and immunohistochemistry. A cell block also shows small groups of cells in their natural arrangement. It adds to, but does not replace, the smears.

   • A: Spinning cells onto a slide is cytocentrifugation.
   • B: Cell culture is used in cytogenetics, not to make cell blocks.
   • D: Freezing fresh tissue in a cryostat gives a frozen section.

2. Question 2 · Hard

   A cytology protocol calls for spinning fluids at 600 g. The rotor radius is 10 cm. Using RCF = 1.118 × 10⁻⁵ × r (cm) × rpm², about what speed should be set?

   1. AAbout 2,300 rpm
   2. BAbout 23,200 rpm
   3. CAbout 1,640 rpm
   4. DAbout 730 rpm

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   Answer: A · About 2,300 rpm

   rpm² = RCF ÷ (1.118 × 10⁻⁵ × r) = 600 ÷ (1.118 × 10⁻⁵ × 10) = 600 ÷ 0.0001118 ≈ 5,370,000, so rpm ≈ 2,317, about 2,300 rpm. Entering the radius as 100 (mm) gives about 730 rpm, the diameter (20 cm) about 1,640 rpm, and meters (0.1) about 23,200 rpm. Protocols state g rather than rpm because rotors differ in radius. Too high a force packs and distorts the cells.

   • B: Entering the radius in meters (0.1) gives about 23,200 rpm.
   • C: Using the 20 cm diameter instead of the radius gives about 1,640 rpm.
   • D: Entering the radius as 100 (mm) instead of 10 cm gives about 730 rpm.

3. Question 3 · Medium

   A cytocentrifuge differs from ordinary centrifugation of a fluid in that it:

   1. ADeposits cells directly onto a slide
   2. BSeparates cells on a density gradient
   3. CMakes cell blocks for paraffin sections
   4. DSpins at ultracentrifuge speeds

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   Answer: A · Deposits cells directly onto a slide

   In a cytocentrifuge the fluid sits in a chamber clamped to a slide with a filter card between them. At low speed the cells settle onto a small circle of the slide while the fluid soaks into the card. This gives a thin layer of well-preserved cells from small, sparse samples such as CSF. Ordinary centrifugation gives a pellet that must then be smeared by hand.

   • B: Density gradients separate blood cells; a cytocentrifuge does not use them.
   • C: Cell blocks are made from a pellet processed like tissue.
   • D: Cytocentrifuges run at low speed to protect the cells.

4. Question 4 · Easy

   The needle commonly used for fine needle aspiration of a palpable lump is about:

   1. A14-16 gauge
   2. B22-25 gauge
   3. C18-19 gauge
   4. D10-12 gauge

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   Answer: B · 22-25 gauge

   FNAC uses fine needles, usually 22-25 gauge, on a 10 or 20 mL syringe, often in a syringe holder. A fine needle causes little pain and bleeding, rarely needs anesthesia and carries very little risk of seeding tumor along the track. The finest needles are used for vascular organs such as the thyroid. Wider needles are used for core biopsy, which removes a cylinder of tissue.

   • A: 14-16 gauge needles are used for core needle biopsy.
   • C: 18-19 gauge needles are wide and give bloody samples.
   • D: 10-12 gauge needles are far too wide for aspiration cytology.

5. Question 5 · Easy

   FNAC of a lump has several advantages over a surgical biopsy. Which is NOT one of them?

   1. AIt rarely needs any anesthesia
   2. BIt is cheap and easily repeated
   3. CIt shows tissue invasion clearly
   4. DIt is quick and done in the OPD

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   Answer: C · It shows tissue invasion clearly

   FNAC samples loose cells, not intact tissue, so it cannot show architecture or capsular and vascular invasion. For this reason it cannot separate a follicular adenoma of the thyroid from a follicular carcinoma. Its advantages are speed, low cost, safety and easy repetition in the outpatient department. When invasion decides the diagnosis, a biopsy is needed.

   • A: Fine needles seldom need local anesthesia.
   • B: Low cost and easy repetition are real advantages.
   • D: Being quick and done in the outpatient department is a real advantage.

6. Question 6 · Medium

   The main advantage of membrane filtration in cytology is that it:

   1. ARecovers almost all cells from sparse fluids
   2. BWorks best on heavily bloodstained fluids
   3. CGives the clearest background of all methods
   4. DNeeds no staining of the filter afterwards

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7. Question 7 · Medium

   FNAC with suction of a vascular thyroid swelling in a 30-year-old woman yields only blood. Which technique is best for the repeat attempt?

   1. AStronger and longer suction
   2. BSuction with the needle held still
   3. CA wider 16-gauge needle with suction
   4. DNeedle alone without suction

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8. Question 8 · Medium

   In FNAC, suction is released before the needle is withdrawn from the lesion so that:

   1. AThe aspirate stays in the needle
   2. BThe needle does not bend as it exits
   3. CThe patient feels less pain at the end
   4. DAir can enter and lift the cells out

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9. Question 9 · Hard

   While a bloody pleural fluid is drawn through a membrane filter, flow stops after only a few mL. What is the best next step?

   1. ARaise the vacuum to force the fluid through
   2. BLet the filter dry and continue later
   3. CCentrifuge the fluid and smear the sediment
   4. DChange to a filter with smaller pores

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10. Question 10 · Easy

    A 62-year-old man has a lesion deep in the liver that cannot be felt. FNAC of it is done:

    1. AOnly at open surgical biopsy
    2. BBy blind insertion at a marked point
    3. CBy palpation, as for any lump
    4. DUnder ultrasound or CT guidance

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11. Question 11 · Medium

    During FNAC of a breast lump in a 35-year-old woman, one smear is quickly stained and examined before she leaves. The main purpose is to:

    1. AGive the patient her final report
    2. BDecide the stain for other smears
    3. CGrade the tumor for the surgeon
    4. DCheck that the sample is adequate

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12. Question 12 · Easy

    What is the most common complication of FNAC of a superficial lump?

    1. APneumothorax
    2. BSpread of infection
    3. CLocal bruising (hematoma)
    4. DTumor seeding along the track

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13. Question 13 · Easy

    Which stain is used on air-dried FNAC smears?

    1. AMay-Grünwald-Giemsa
    2. BPapanicolaou stain
    3. CPeriodic acid-Schiff
    4. DHematoxylin and eosin

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14. Question 14 · Easy

    What is the main purpose of a syringe holder (pistol grip) in FNAC?

    1. AGives a stronger vacuum than a plain syringe
    2. BKeeps the aspirate sterile for culture
    3. CLets one hand fix the lump while the other aspirates
    4. DMakes the needle cut a solid core of tissue

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15. Question 15 · Medium

    Pleural fluid from a 70-year-old woman arrives with a large fibrin clot at the bottom of the bottle. How should the clot be handled?

    1. AFix it and process it as a cell block
    2. BBreak it up by shaking the bottle hard
    3. CFreeze it and cut a frozen section
    4. DDiscard it and smear only the fluid

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16. Question 16 · Hard

    FNAC of matted cervical lymph nodes in a 24-year-old man yields thick, cheesy, white material. Besides routine smears, what is the most useful step?

    1. AFix all of the material in Bouin's fluid
    2. BRepeat the aspiration with a 16-gauge needle
    3. CStain a smear by Ziehl-Neelsen for AFB
    4. DReport it as inadequate and discard it

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17. Question 17 · Medium

    Why are a few units of heparin often added to the bottle when a large volume of ascitic fluid is collected for cytology?

    1. ATo lyse red cells in a bloody tap
    2. BTo stop clots forming that trap cells
    3. CTo fix the cells during transport
    4. DTo preserve the fluid without cooling

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18. Question 18 · Hard

    Urine for cytology is to be spun in a centrifuge whose rotor radius is 12 cm, at 2,000 rpm. Using RCF = 1.118 × 10⁻⁵ × r (cm) × rpm², about what RCF is achieved?

    1. A1,073 × g
    2. B268 × g
    3. C5,366 × g
    4. D537 × g

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19. Question 19 · Easy

    A pleural fluid for cytology reaches the laboratory late in the evening and cannot be processed until the next morning. How should it be kept?

    1. AIn the incubator at 37°C
    2. BIn a refrigerator at about 4°C
    3. CAt room temperature in sunlight
    4. DIn a freezer at -20°C

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20. Question 20 · Medium

    A Pap-stained FNAC smear shows swollen cells with pale, smudged nuclei and no chromatin detail, while the next smear is good. The most likely cause is:

    1. AAir-drying before fixation
    2. BToo thin a smear
    3. COverstaining in haematoxylin
    4. DFixation in 95% alcohol

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21. Question 21 · Easy

    For routine smears from the sediment of a serous fluid, the fluid is commonly centrifuged at about:

    1. A1,500-2,000 rpm for 10 minutes
    2. B10,000 rpm for 60 minutes
    3. C500 rpm for 2 minutes
    4. D5,000 rpm for 30 minutes

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22. Question 22 · Hard

    A pleural fluid has a cell count of 20,000/µL. Cytospin slides made from 200 µL of the undiluted fluid show a thick central button of overlapping, distorted cells that cannot be assessed. What is the best correction?

    1. ADilute the fluid with saline before spinning
    2. BLoad a larger volume of the same fluid
    3. CSpin at a higher speed for longer
    4. DFix the fluid in alcohol before spinning

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23. Question 23 · Medium

    In the plasma-thrombin method of preparing a cell block, thrombin is added to the sediment with plasma in order to:

    1. AFix the cells before processing
    2. BForm a clot that holds the cells together
    3. CDigest the mucus around the cells
    4. DLyse the red cells in the sediment

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24. Question 24 · Easy

    What is the main advantage of making a cell block from an effusion sediment?

    1. AFaster report than a direct smear
    2. BNo need for fixation of the sediment
    3. CBetter nuclear detail than a Pap smear
    4. DMany sections for special stains and IHC

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25. Question 25 · Medium

    In FNAC smears, long streaks of stretched nuclear material (crush artefact) are mainly caused by:

    1. AHeavy pressure while spreading the drop
    2. BUsing a needle of fine gauge
    3. CToo little material on the slide
    4. DDelay in fixation of the smear

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