HIS Frozen Sections

Question 1

What is the CAP accreditation standard time for cryotomy?

Answer 1

20 minutes

Question 2

4 major applications of cryotomy

Answer 2

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

Question 3

Cryotomy in intra-operative consultations

Answer 3

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

Question 4

Enzyme histochemistry in cryotomy

Answer 4

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

Question 5

Immunofluorescent techniques in cryotomy

Answer 5

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

Question 6

Lipid stains in cryotomy

Answer 6

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

Question 7

Describe procedure of cyrotomy

Answer 7

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

Question 8

How can freezing artefact be minimized ?

Answer 8

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

Question 9

Cryostat temp for highly cellular tissue

Answer 9

Warmer temps (-10 to -15°C)

Question 10

Cryostat temp for open and connective tissue (including adipose)

Answer 10

Colder temps (-20 to -30°C)

Question 11

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

Answer 11

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

Question 12

Intra-operative tissues are stained using…

Answer 12

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

Question 13

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

Answer 13

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

Question 14

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

Answer 14

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

Question 15

Tissue Chattering

Answer 15

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

Question 16

Troubleshoot Tissue Chattering

Answer 16

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

Question 17

Tissue Shattering

Answer 17

cryostat temperature is too cold

Question 18

Shattering is common in which tissue ?

Answer 18

Lymph nodes

Question 19

Troubleshoot Tissue Shattering

Answer 19

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

Question 20

Tissue Compression

Answer 20

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

Question 21

Troubleshoot Tissue Compression

Answer 21

• re-cool block on ice
• use a new blade

Question 22

Tissue Scores

Answer 22

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

Question 23

Troubleshoot Scores

Answer 23

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

Question 24

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

Answer 24

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

Question 25

Describe End-of-day Cryostat maintenance

Answer 25

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

Question 26

Describe periodic cryostat maintenace

Answer 26

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