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MLSCI 350 > 4: Frozen Sections > Flashcards

4: Frozen Sections Flashcards

1
Q

What is the CAP accreditation standard time for cryotomy?

A

20 minutes

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2
Q

4 major applications of cryotomy

A
  1. Intra-operative consultations
  2. Enzyme histochemistry
  3. Immunofluorescent techniques
  4. Lipid stains
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3
Q

Cryotomy in intra-operative consultations

A

during surgery, physician can request Histo lab to identify an unexpected finding or confirm that a biopsy margin is negative for cancer before closing the patient

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4
Q

Enzyme histochemistry in cryotomy

A

Freezing tissue prevents:
1. Degradation after being removed from blood supply
2. Enzyme activity being reduced from chemical fixation

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5
Q

Immunofluorescent techniques in cryotomy

A
  • Labile antigens are preserved from being denatured by chemical fixation
  • Antibodies with fluorescent labels can be used
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6
Q

Lipid stains in cryotomy

A
  • Preserves lipids that would be removed by solvents in tissue processing
  • Neutral lipids (fat) can be visualized
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7
Q

Describe procedure of cyrotomy

A
  1. Rapid freezing of tissue
  2. Typically set cryostat at -20°C
  3. Freeze tissue on FSC
  4. Cut sections one by one onto slides
  5. Fix briefly in formalin* or alcohol
  6. Leave to dry or rinse in water immediately before staining
  7. Intra-operative = stain with H&E or Diff-Quik (commericial Romanowsky stain)
  8. After pathologist permission, tissue is thawed and fixed in formalin
  9. After overnight processing, tissue is cut and compared to frozen section
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8
Q

How can freezing artefact be minimized ?

A
  • Freeze tissue as rapidly as possible = smaller crystals
  • Use heat extractors, dry ice, or isopentane cooled with liquid nitrogen
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9
Q

Cryostat temp for highly cellular tissue

A

Warmer temps (-10 to -15°C)

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10
Q

Cryostat temp for open and connective tissue (including adipose)

A

Colder temperatures (-20 to -30°C)

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11
Q

T or F: Sections are cut one at a time, rather than forming a ribbon

A

TRUE; Sections are cut one at a time, rather than forming a ribbon

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12
Q

Intra-operative tissues are stained using…

A

H&E or Diff-Quik (commercial Romanowsky dye)

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13
Q

Why must frozen sections be compared with thawed sections the following day ?

A

Frozen (fresh) sections are inferior in quality compared to fixed tissue

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14
Q

Why must PPE be worn when using a cryostat ? (N95, mask, gloves, goggles, gown)

A

Frozen tissue has not been processed with fixatives/ solvents = potentially infectious

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15
Q

Tissue Chattering

A
  • Regular pattern of horizontal lines = “Venetian blind”
  • Tissue/ block is too cold
  • Cryotome component is loose
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16
Q

Trouble Tissue Chattering

A
  • warm surface of block directly
  • tighten all levers and clamps of cryotome
17
Q

Tissue Shattering

A

cryostat temperature is too cold

18
Q

Shattering is common in which tissue ?

A

Lymph nodes

19
Q

Troubleshoot Tissue Shattering

A

Use heat from gloved thumb to quickly soften the surface of block

20
Q

Tissue Compression

A
  • section becomes smaller than face of block bc tissue collapsed onto edge of bade when cutting
  • block is too warm
  • blade is dull
21
Q

Troubleshoot Tissue Compression

A
  • re-cool block on ice
  • use a new blade
22
Q

Tissue Scores

A
  • vertical lines (PERPENDICULAR to blade) on section
  • due to blade defect OR calcification on block
23
Q

Troubleshoot Scores

A
  • reposition/ use a new blade
  • if scores persist = tissue is calcified = inform pathologist
24
Q

Why would tissue debris float around in the cryostat ? How is this corrected ?

A

Due to static electricity
- Humidify room or wipe down interior with alcohol

25
Q

Describe End-of-day Cryostat maintenance

A
  • disinfect with 70% alcohol at end of day
  • ensure automatic defrost cycle is turned on
26
Q

Describe periodic cryostat maintenace

A
  • Defrost and decontaminate using Oxivir/ CaviCide
  • UV-light disinfection
  • Automatic defrost cycles
  • Vacuum cooling coils on the back/ sides of cryostat

MLSCI 350 (6 decks)

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