Frozen section procedure
Encyclopedia
The frozen section procedure is a pathological
laboratory
procedure to perform rapid microscopic
analysis of a specimen. It is used most often in oncological surgery. The technical name for this procedure is cryosection.
The quality of the slides produced by frozen section is of lower quality than formalin fixed, wax embedded tissue processing. While diagnosis can be rendered in many cases, fixed tissue processing is preferred in many conditions for more accurate diagnosis.
The intraoperative consultation is the name given to the whole intervention by the pathologist
, which includes not only frozen section but also gross
evaluation of the specimen, examination of cytology
preparations taken on the specimen (e.g. touch imprints), and aliquoting of the specimen for special studies (e.g. molecular pathology techniques, flow cytometry). The report given by the pathologist is usually limited to a "benign" or "malignant" diagnosis, and communicated to the surgeon operating via intercom. When operating on a previously confirmed malignancy, the main purpose of the pathologist is to inform the surgeon if the surgical margin is clear of residual cancer, or if residual cancer is present at the surgical margin. The method of processing is usually done with the bread loafing
technique. But margin controlled surgery (CCPDMA
) can be performed using a variety of tissue cutting and mounting methods, including mohs surgery
.
, 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 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 (0.83612736 m²), and minimal ventilation is required compared to a standard wax embedded specimen laboratory.
in 1905. Wilson developed the technique from earlier reports at the request of Dr William Mayo
, surgeon and one of the founders of the Mayo Clinic
. Earlier reports by Dr Thomas S. Cullen at Johns Hopkins Hospital
in Baltimore
also involved frozen section, but only after formalin fixation, and pathologist Dr William Welch, also at Hopkins, experimented with Cullen's procedure but without clinical consequences. Hence, Wilson is generally credited with truly pioneering the procedure (Gal & Cagle, 2005).
Anatomical pathology
Anatomical pathology or Anatomic pathology is a medical specialty that is concerned with the diagnosis of disease based on the gross, microscopic, chemical, immunologic and molecular examination of organs, tissues, and whole bodies...
laboratory
Medical laboratory
A medical laboratory or clinical laboratory is a laboratory where tests are done on clinical specimens in order to get information about the health of a patient as pertaining to the diagnosis, treatment, and prevention of disease.-Departments:...
procedure to perform rapid microscopic
Microscope
A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...
analysis of a specimen. It is used most often in oncological surgery. The technical name for this procedure is cryosection.
The quality of the slides produced by frozen section is of lower quality than formalin fixed, wax embedded tissue processing. While diagnosis can be rendered in many cases, fixed tissue processing is preferred in many conditions for more accurate diagnosis.
The intraoperative consultation is the name given to the whole intervention by the pathologist
Pathology
Pathology is the precise study and diagnosis of disease. The word pathology is from Ancient Greek , pathos, "feeling, suffering"; and , -logia, "the study of". Pathologization, to pathologize, refers to the process of defining a condition or behavior as pathological, e.g. pathological gambling....
, which includes not only frozen section but also gross
Gross examination
Gross examination or "grossing" is the process by which pathology specimens are inspected with the bare eye to obtain diagnostic information, while being processed for further microscopic examination....
evaluation of the specimen, examination of cytology
Cytopathology
Cytopathology is a branch of pathology that studies and diagnoses diseases on the cellular level. The discipline was founded by Rudolf Virchow in 1858. A common application of cytopathology is the Pap smear, used as a screening tool, to detect precancerous cervical lesions and prevent cervical...
preparations taken on the specimen (e.g. touch imprints), and aliquoting of the specimen for special studies (e.g. molecular pathology techniques, flow cytometry). The report given by the pathologist is usually limited to a "benign" or "malignant" diagnosis, and communicated to the surgeon operating via intercom. When operating on a previously confirmed malignancy, the main purpose of the pathologist is to inform the surgeon if the surgical margin is clear of residual cancer, or if residual cancer is present at the surgical margin. The method of processing is usually done with the bread loafing
Bread loafing
Bread loafing is a common method of processing surgical specimen for histopathology. The process involves cutting the specimen into 3 or more sections. The cut sections are mounted by embedding in paraffin or frozen medium. The cut edge is then thinly sliced with a microtome or a cryostat...
technique. But margin controlled surgery (CCPDMA
CCPDMA
CCPDMA is the acronym for "complete circumferential peripheral and deep margin assessment". It is the preferred method for the removal of certain cancers, especially skin cancers.A classical example of CCPDMA is Mohs surgery...
) can be performed using a variety of tissue cutting and mounting methods, including mohs surgery
Mohs surgery
Mohs surgery, also known as chemosurgery, created by a general surgeon, Dr. Frederic E. Mohs, is microscopically controlled surgery used to treat common types of skin cancer. It is one of the many methods of obtaining complete margin control during removal of a skin cancer using frozen section...
.
Procedure
The key instrument for cryosection is the cryostatCryostat
A cryostat is a device used to maintain cold cryogenic temperatures. Low temperatures may be maintained within a cryostat by using various refrigeration methods, most commonly using cryogenic fluid bath such as liquid helium. Hence it is usually assembled into a vessel, similar in construction...
, which is essentially a microtome
Microtome
A microtome is a sectioning instrument that allows for the cutting of extremely thin slices of material, known as sections. Microtomes are an important device in microscopy preparation, allowing for the preparation of samples for observation under transmitted light or electron radiation...
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 consisting of poly ethylene glycol
Ethylene glycol
Ethylene glycol is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colorless, syrupy, sweet-tasting liquid...
and polyvinyl alcohol
Polyvinyl alcohol
Polyvinyl alcohol is a water-soluble synthetic polymer .-Properties:...
; 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
Eosin
Eosin is a fluorescent red dye resulting from the action of bromine on fluorescein. It can be used to stain cytoplasm, collagen and muscle fibers for examination under the microscope. Structures that stain readily with eosin are termed eosinophilic....
, the H&E stain
H&E stain
H&E stain, HE stain or hematoxylin and eosin stain is a popular staining method in histology. It is the most widely used stain in medical diagnosis; for example when a pathologist looks at a biopsy of a suspected cancer, the histological section is likely to be stained with H&E and termed H&E...
). The preparation of the sample is much more rapid than with traditional histology
Histology
Histology is the study of the microscopic anatomy of cells and tissues of plants and animals. It is performed by examining cells and tissues commonly by sectioning and staining; followed by examination under a light microscope or electron microscope...
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 (0.83612736 m²), and minimal ventilation is required compared to a standard wax embedded specimen laboratory.
Uses
The principal use of the frozen section procedure is the examination of tissue while surgery is taking place. This may be for various reasons:- In the performance of Mohs surgeryMohs surgeryMohs surgery, also known as chemosurgery, created by a general surgeon, Dr. Frederic E. Mohs, is microscopically controlled surgery used to treat common types of skin cancer. It is one of the many methods of obtaining complete margin control during removal of a skin cancer using frozen section...
- a simple method for 100% margin control of a surgical specimen. - If a tumor appears to have metastasizedMetastasisMetastasis, or metastatic disease , is the spread of a disease from one organ or part to another non-adjacent organ or part. It was previously thought that only malignant tumor cells and infections have the capacity to metastasize; however, this is being reconsidered due to new research...
, a sample of the suspected metastasis is sent for cryosection to confirm its identity. This will help the surgeon decide whether there is any point in continuing the operation. Usually, aggressive surgery is performed only if there is a chance to cure the patient. If the tumor has metastasized, surgery is usually not curative, and the surgeon will choose a more conservative surgery, or no resection at all. - If a tumor has been resected but it is unclear whether the surgical marginSurgical marginSurgical margin, also known as tumor free margin, free margin, normal skin margin, and normal tissue margin, usually refers to the visible normal tissue or skin margin that is removed with the surgical excision of a tumor, growth, or malignancy.-Definition:Surgical margin in a surgery reports...
is free of tumor, an intraoperative consultation is requested to assess the need to make a further resection for clear margins. - In a sentinel node procedure, a sentinel node containing tumor tissue prompts a further lymph node dissection, while a benign node will avoid such a procedure.
- If surgery is explorative, rapid examination of a lesion might help identify the possible cause of a patient's symptoms. It is important to note, however, that the pathologist is very limited by the poor technical quality of the frozen sections. A final diagnosis is rarely offered intraoperatively.
- Rarely, cryosections are used to detect the presence of substances lost in the traditional histology technique, for example lipids. They can also be used to detect some antigens masked by formalin.
- The cryostat is available in a small portable device weighing less than 80 lb (36.3 kg), to a large stationary device 500 lb (226.8 kg) or more. The entire histologic laboratory can be carried in one portable box, making frozen section histology a possible tool in primitive medicine.
History
The frozen section procedure as practiced today in medical laboratories is based on the description by Dr Louis B. WilsonLouis B. Wilson
Louis B. Wilson, M.D. was the chief of pathology at Mayo Clinic from 1905 to 1937. Wilson is most famous for initiating the routine use of the frozen section procedure for rapid intraoperative diagnosis....
in 1905. Wilson developed the technique from earlier reports at the request of Dr William Mayo
William Mayo
William Mayo is the name of:* William B. Mayo , former chief engineer of the Ford Motor Company* Two co-founders of the Mayo Clinic:** William Worrall Mayo **William James Mayo...
, surgeon and one of the founders of the Mayo Clinic
Mayo Clinic
Mayo Clinic is a not-for-profit medical practice and medical research group specializing in treating difficult patients . Patients are referred to Mayo Clinic from across the U.S. and the world, and it is known for innovative and effective treatments. Mayo Clinic is known for being at the top of...
. Earlier reports by Dr Thomas S. Cullen at Johns Hopkins Hospital
Johns Hopkins Hospital
The Johns Hopkins Hospital is the teaching hospital and biomedical research facility of Johns Hopkins University School of Medicine, located in Baltimore, Maryland . It was founded using money from a bequest by philanthropist Johns Hopkins...
in Baltimore
Baltimore
Baltimore is the largest independent city in the United States and the largest city and cultural center of the US state of Maryland. The city is located in central Maryland along the tidal portion of the Patapsco River, an arm of the Chesapeake Bay. Baltimore is sometimes referred to as Baltimore...
also involved frozen section, but only after formalin fixation, and pathologist Dr William Welch, also at Hopkins, experimented with Cullen's procedure but without clinical consequences. Hence, Wilson is generally credited with truly pioneering the procedure (Gal & Cagle, 2005).
External links
- JAMA patient page on frozen section procedure
- Description of the frozen section procedure