What Is Surgical Pathology?
Surgical pathology is a part of anatomic pathology, involving the study of tissue samples removed from patients during surgery. A pathologist then evaluates the sample to diagnose a disease and decide on a treatment plan. Surgical pathology can be conducted in a wide variety of organs and medical subspecialties. Surgical pathology includes assessments of the specimen by gross inspection and microscopic examination of the tissue section or the fluid sample collected from the specimen. Molecular diagnostics is a new technique of examination of tissue and cell specimens to analyze DNA (deoxyribonucleic acid) and proteins in the blood. This technology is useful in many aspects; some include finding infectious agents in body tissues, distinguishing between benign and malignant white blood cells, and detecting early genetic changes which may lead to cancer. Surgical pathology can also be used for providing second opinions.
What Are the Types of Surgical Specimens Collected?
Pathologists collect different types of surgical specimens, depending on the type of diseases and surgery:
- Tissue Biopsy - It is a procedure to remove a small piece of tissue from the affected body part, which is then analyzed in a laboratory for diagnostic purposes. A tissue biopsy can be taken during a surgical procedure or carried out as a specific procedure. Different types of tissue biopsy include endoscopic biopsy, incisional biopsy, excisional biopsy, and core biopsy or needle biopsy.
- Surgical Resection - It is a surgical method where possible, and necessary tumor tissue is removed, and the sample is taken to the laboratory for evaluation purposes. Surgical resections are mostly done in already detected malignant tumor cases.
- Cytology - It is also called cytopathology, which uses a sample of bodily tissue or fluid to examine certain types of cells for diagnostic purposes. The most common methods for collecting cytology specimens are fine needle aspiration (FNA), tests on body fluids, and scrape or brush cytology.
How Is a Specimen Prepared for Surgical Pathology?
For investigation of specimens under the microscope, the cell or tissue specimens must be made into thin slices, called sections. To make the sections of the specimen, processing should be done to make the specimen solid so that it can be cut into very thin slices.
For the tissue examination, chemical fixing of the specimen should be carried out; typically, a chemical called formaldehyde (formalin) is used along with some other chemicals. This is done to stabilize the cells for further processing, which submerges the tissue in an automated machine. During this process, it removes water in the specimen and replaces it with molten paraffin wax. After processing, the tissue sample is embedded into a wax block of paraffin to be sliced using a machine called a microtome. The paraffin-embedded tissue sample is then cut into very thin slices that are positioned onto microscopic slides. Later slides are stained with dyes called hemotoxin and eosin, which helps to visualize different parts of the cell better. This process is called histologic examination. Preparing the fixed sections can generally take many days. So the pathologist usually sends the surgical pathology report to the doctor within ten days after the surgery biopsy is performed. The fixation of the tissue sample can provide the maximum detail of the tissue sample, and these fixed slides can be used for analysis in the future if required.
Frozen Sectioning - It is another technique used by a pathologist for tissue examination when an immediate intra-operative (during surgery) pathology consult about a tissue sample is required. Frozen sectioning is usually carried out during surgery to provide a rapid diagnosis to the surgeon about abnormal tissue area and their extent while the patient is in the operative room.
To prepare frozen sections, the tissue sample is grossly examined by the pathologist to determine which part should be examined under a microscope. Then the tissue is rapidly frozen in a special solution that forms like an ice cube around the sample. Then the sample is cut into thin slices using a specialized instrument called a cryostat, stained in a series of dyes, and examined by a pathologist under a microscope. The whole process can be done in about 15 to 20 minutes. Frozen sectioning does not provide clear tissue features as obtained by the tissue embedded in the wax method. However, they are very helpful in making quick decisions during the surgery.
Cytology Specimens Processing - The processing of cytology specimens depends on the type of specimen collected. Generally, specimens are smeared on glass slides, which are called smears. The slides are then sent to the laboratory, where they are stained in different color dyes, similar to that used for biopsy samples. If the specimen is collected from the body fluids, it cannot be smeared as it is too diluted. So the cells are concentrated before staining. Later the samples are stained and examined by the pathologist.
What Is the Difference Between Clinical and Surgical Pathology?
The workflows of surgical pathology are much faster than clinical pathology as surgical pathology consultations are done under high time pressure as the patient is still being operated. So every minute counts when the patient is still on the operation table. In recent times, intraoperative surgical pathology can be performed within 20 minutes after collecting the specimen. The slide preparation time is reduced because of the frozen section procedure and quick cutting and fixing techniques.
What Is the Setback of Surgical Pathology?
The slide processing time is very crucial in surgical pathology, as it is done during intraoperative procedures. However, some factors influence the time it takes to perform an intraoperative consultation, like the lack of pathologists or the uneven distribution of pathologists within a country. These factors can lead to limitations and challenge a consultation's feasibility, which may increase the follow-up surgery chances. Moreover, when the operating room and the pathology lab are located far away, or when there is no in-house pathologist, the specimens should be taken to a pathology lab, or the pathologist is required to reach the hospital in time. This can lead to logistic challenges like storing, transportation, and delivering, which can also lengthen the overall procedure time and increase the consultation cost.
What Does the Surgical Pathology Report Contain?
Gross description:
A gross description of a surgical pathology specimen includes the color, size, shape, and weight of a tissue sample as noted by the naked eye. The report may include any visible abnormalities in the sample. The report also indicates the site from where the sample was taken, the number of samples collected, and whether lymph nodes were removed or not.
Microscopic description:
This includes the number and type of cells identified in the tissue sample, the abnormal changes in the cell, and whether these changes are notable cell features. This report also includes the location of abnormal cells in the margins or lymph nodes. The description also includes additional tests conducted on the tissue samples and their results.
Conclusion
Surgical pathology is a study of specimen collection during the surgical procedure that helps with diagnosis and treatment planning. It should be performed in a short duration of time, as a surgical pathology report must be created when the patient is still in the operating room. However, surgical pathology also faces many complications due to the lack of pathologists, inadequate hospital facilities, etc. Good pathological results can be obtained when adequate changes are made to correct the setbacks.
