Topic 4 - Frozen Sectioning

What are the four major applications for frozen sectioning?

I/O consultations, enzyme histochemistry, immunofluorescent technique, lipid staining

Why do I/O consults need frozen tissue?

If the surgeon wants to identify an unexpected finding or confirm biopsy margin is negative

why does enzyme histochemistry need frozen tissue?

It helps preserve enzyme activity since it is reduced after chemical fixation and when removed from the blood supply

Why do immunofluorescent techniques need frozen tissue?

Chemical fixation will denature/alter antigens of interest. Aldehyde also creates autofluorescence

Why do lipid stains require frozen sections?

They usually get dissolved during processing and frozen sections do not get processed

What is the CAP accreditation standard time for frozen sectioning?

20 minutes

What is freezing artifact?

When frozen tissue contains large holes and distorted morphology from large crystals forming during slow freezing

How can we avoid freezing artifact?

Tissue must be frozen quickly

What is the cryostat temperature for general purpose cutting?

-20C

What is the cryostat temperature for dense, cellular tissue?

-10C to -15C

What is the cryostat temperature for adipose tissue?

-25C to -30C

What is Frozen Sectioning Compound?

Viscous liquid that quickly freezes to support the tissue

What is used to briefly fix the frozen section?

Formalin or alcohol

Why do we thaw the frozen tissue and process it overnight?

As a quality check since we cannot use frozen sections as a diagnosis

What is chatter?

Horizontal lines (venetian blinds) in the tissue due to block being too cold or loose component

What is shattering?

Fragmentation due to cold cryostat temperature

What is compression?

When the section is smaller than the face of the block due to warm block or dull blade

What are lines/scores?

Macroscopic element with vertical lines in the tissue due to blade defect or calcification

Which disinfectant should be used for the cryostat?

70% ethanol

What should be used to decontaminate the cryostat?

Oxivir or Cavicide

What are the three ways we can freeze tissue?

In the cryostat, by dry ice, or nitrogen cooled isopentane

What temperature should heart, lung, skin, pancreas, and cervix be frozen at?

-16 to -20C

What temperature should brain, liver, thyroid, and lymph nodes be frozen at?

-7 to -13C