Diagnostic Cytopathology

• Normal Constituents of a Cervical Smear

  Squamous Cells

  • Superficial
  • Intermediate
  • Parabasal
  • Metaplastic

  Columnar (Glandular) Cells

  • Endocervical cells
  • Endometrial cells

  Other normal cells

  • Blood cells (RBC, PMNL, Neutrophils, Bacteria, Spermatozoa)

   
• Advantages of FNA over other procedures:

  • Rapid diagnosis
  • Safety
  • High reliability
  • Economic efficiency
  • Minimally invasive
  • Useful for palpable masses and deep seated lesions with few side effects
• Safety of FNAs

  Minimally invasive - high safety record

  Volume of material which can be aspirated with a 22 gauge needle is 15.3mm^3

  Needle tract local seeding and dissemination of disease by lymphatics and blood stream
• Needles/Syringes

  • Disposable hypodermic needles with long bevels
  • 22-27 gauge but larger diameter needle for extremely viscous fluid i.e. 19 gauge
  • Larger bore needles collect more material from loosely structured cellular organs or lesions
  • Smaller bore needles - tissue with few epithelial cells and extensive fibrosis. They penetrate the fibrous stroma better e.g. invasive lobular carcinoma of breast
  • Slip tip disposable syringes better for ease of removing and reattaching the needle
  • Aspirations have tubing between the needle and syringe
• Rules on Using Suction

  Suction alone will only work when the targeted lesion contains fluid

  Except for fluids, the aspirate should not reach the barrel of the syringe

  Without suction reduces the amount of blood when dealing with vascular organs/lesions

  No suction:

  When using needle without suction, it is held by hub so it can be accurately positioned and easier to manipulate

  Solid tissue requires the needle tip to act as a cutting instrument. As it is moved back and forth through the tissue and tiny tissue fragments become dislodge and collect inside the needle.

   
• FNA Contraindications

  Only tumours that shouldn't have an FNA:

  • Carotid Body Tumours and Pheochromocytomas (Neuroendocrine tumour of adrenal glands)

  If FNA occurs on these, it can cause syncope and episodes of acute hypertension

  They can be diagnosed by CT for later surgery

   
• Preparation for FNA

  NATA requires at least 2 identifiers: Full Name & DOB

  On specimen bottle, forms and accompanying paperwork - slides are labelled with lab request no., patient name, specimen site, pass # - i.e. DQ1 and PAP1, then DQ2 and

  In an FNA clinic situation:

  1. Be set up for 2 patients from start
  2. Gather as much clinical info as possible. The feel of the needle going through the lesion is important in the triple test
  3. Always ask the nurse name and location of lesion on each pass delivered
  4. Do not accept the pass "as given"
• Basic Smear Technique

  Goal - allow optimal distribution of well-preserved cells & small tissue fragments on the slide

  • 1-2 droplets of material expelled onto slide
  • Pick slide up labelled end
  • Pick up a clean slide with dominant hand
  • Place top edge of slide until it touches and then covers the droplet and the 2 slides are flush
  • In one smooth rapid motion the material is spread by pulling the top slide along the entire length of the bottom slide
  • The 2 slides are kept flush throughout the smearing process to avoid scraping artefact
• Types of Fixation Required

  Direct Smears:

  • Diff Quik stain is used on air-dried material - IMMEDIATELY
  • Briefly fixed in alcohol/methanol prior to staining
  • Papanicolaou stain is on wet-fixed material - Done in Lab
  • Fixed for at least 15 minutes in alcohol

  1. Haematoxylin for nuclear detail
  2. Counterstains for cytoplasm
  3. OG6 - Keratin
  4. EA65 is better for non-gynae (EA50 for gynae)

  All stains should be filtered to prevent cross-contamination with malignant specimens

  Extracellular Substances:

  • Free mucin, Colloid & Ground substance (metachromatic stroma)
• Limitations to FNA

  Blood Clotting:

  • Procedure of aspiration should be fairly rapid to prevent
  • Distorts architecture of cells clusters obscuring microscopic detail
  • Alcohol better fixation for blood clotting

  Crush Artefact:

  • Caused by either too much pressure during smear prep or slides aren't flush with each other.
  • Lymph nodes and Small Cell Carcinoma are more likely to have these.

  False Positive Diagnoses:

  • Quality of material
  • Scant material with only a few abnormal cells
  • Improperly placed needle smears
• Problems with Breast FNAs

  Sampling Errors

  • Lack of experience
  • Wrong mass sampled
  • Fibrosis/sclerosis
  • Small lesion (<1cm)

  Interpretative Errors

  • Making a diagnosis on unsatisfactory or uninterpretable samples
  • Lack of experience
  • Pregnancy
  • Reactive lesions: inflammation, radiation, pregnancy
  • Cellular benign lesions: fibroadenoma, epitheliosis and papillomatosis
  • Well differentiated carcinoma

  Lactation Changes

   

  Ancillary Tests:

  • Triage of FNA Material:
  • IHChormone Receptor Status
  • Flow Cytometry (lymphocyte markers)
  • Electron microscopy
  • Microbiology
  • Molecular/genetic testing
  • Immunology
• Role of Scientist at FNAs

  Primary purpose is to provide an on-site assessment at an FNA to ensure that the lesion is adequately sampled

  There is a supposed pre-defined threshold of adequacy

  6 groups of 10 cells

  BUTadequacy really depends on the sample and the clinical circumstances and what ancillary testing is required

  i.e. fibrotic lesion or lipoma will not yield many cells but is really satisfactory within the clinical picture
• Risk Factors for Bladder Cancer:

  • Male >50
  • Chemical exposures:
  • Cigarette smoking
  • Dyes in rubber and textile industry
  • Chemotherapy drug
  • Radiation of the pelvis
  • Renal transplant
  • Recurrent infections with bacteria, fungi and viruses
  • Occupations - dry cleaner, paper manufacture, rope and twin maker, apparel, leather tanners