Biopsies are small samples of tissue taken from a mass or tumor that are examined under a microscope to make a diagnosis. Biopsies are used most often to determine whether cancer cells are present, although certain infections and other diseases can be diagnosed as well. A specific type of biopsy procedure called the frozen section was developed in order to make a rapid diagnosis of a mass during surgery. The December 28, 2005, issue of JAMA includes an article about the origins of the frozen section technique.

Frozen section procedure
During the frozen section procedure, the surgeon removes a portion of the tissue mass. This biopsy is then given to a pathologist (a doctor who examines tissues and uses laboratory tests to make a diagnosis). The pathologist freezes the tissue in a cryostat machine, cuts it with a microtome, and then stains it with various dyes so that it can be examined under the microscope. The procedure usually takes only minutes.
https://jamanetwork.com/journals/jama/fullarticle/202100

https://en.wikipedia.org/wiki/Frozen_section_procedure
Procedure
Tissue embedded within OCT, mounted on a chuck in a cryostat and ready for section production
The key instrument for cryosection is the cryostat, which is essentially a microtome inside a freezer. The microtome can be compared to a very accurate "deli" slicer, capable of slicing sections as thin as 1 micrometre. The usual histology slice is cut at 5 to 10 micrometres. The surgical specimen is placed on a metal tissue disc which is then secured in a chuck and frozen rapidly to about –20 to –30 °C. The specimen is embedded in a gel like medium called OCT and consisting of poly ethylene glycol and polyvinyl alcohol; this compound is known by many names and when frozen has the same density as frozen tissue. At this temperature, most tissues become rock-hard. Usually a lower temperature is required for fat or lipid rich tissue. Each tissue has a preferred temperature for processing. Subsequently it is cut frozen with the microtome portion of the cryostat, the section is picked up on a glass slide and stained (usually with hematoxylin and eosin, the H&E stain). The preparation of the sample is much more rapid than with traditional histology technique (around 10 minutes vs 16 hours). However, the technical quality of the sections is much lower. The entire laboratory can occupy a space less than 9-square-foot (0.84 m2), and minimal ventilation is required compared to a standard wax embedded specimen laboratory.

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Note added at 3 hrs (2018-08-15 21:55:10 GMT)
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https://www.cancer.gov/about-cancer/diagnosis-staging/diagno...

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Note added at 4 days (2018-08-20 10:07:56 GMT) Post-grading
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