Tissue for the procedure in the image must be which of the following?

• A. Frozen and unfixed
• B. Fixed
• C. Paraffin-embedded
• D. Fresh and fixed

Answer: (A)

For a rapid intraoperative assessment, tissue must be unfixed and frozen. Freezing allows the pathologist to cut very thin sections in a cryostat and stain them quickly for an immediate microscopic look during surgery. Fixation alters tissue proteins, creates cross-links, and makes rapid sectioning and interpretation unreliable, which defeats the purpose of the quick freeze technique. Paraffin embedding requires fixation, dehydration, and infiltration, processes that take hours and delay diagnosis. “Fresh and fixed” isn’t compatible, since fixation precludes the tissue being fresh for immediate freezing and sectioning. Thus, unfixed tissue that is frozen is the appropriate choice for this procedure.