Biopsy is a procedure in which a sample of tissue/ cells is taken from the body, processed in a laboratory and then examined under a microscope. There are different types of biopsies which can be performed.
The most common indication for a biopsy is to determine whether tissue or a tumor is malignant (cancerous) or not. It can also be helpful in detecting certain infections or inflammation.
Who Performs Biopsy?
Biopsy is usually performed by a surgeon, physician or interventional radiologist. Some biopsies like fine needle aspiration biopsy and bone marrow biopsy can be performed by pathologists.
Indications and sites of biopsy
The most common indication of a biopsy is to determine whether a lesion is benign or malignant.
Besides, it is also indicated in a host of other conditions having inflammatory or infectious etiology, especially when there is uncertainty of diagnosis.
It is useful in patients with cirrhosis and hepatitis to establish the cause and to assess the degree of inflammatory activity and extent of fibrosis.
It can be obtained either through laproscopy or open surgery or percutaneously under ultrasound guidance (Menghini method)
Biopsy along with immunofluorescence microscopy is used to diagnose a host of kidney lesions like nephritic and nephrotic syndrome, glomerulonephritis, pyelonephritis, etc. It can be carried out percutaneously or during open surgery.
It can be obtained through FNAB, core needle biopsy, transbronchial biopsy (using a bronchoscope) or thoracoscopy.
With the help of endoscopes, the entire gastrointestinal tract can be visualized and samples can be taken for biopsy. Polyps, ulcerative lesions or any other abnormal appearing area can be biopsied.
Malignancies, inflammatory bowel disease, gastroesophageal reflux disease, etc can be diagnosed on biopsy.
A sample of outer layer of bony tissue is removed to diagnose bone lesions including cancer, infections and other undiagnosed bone lesions.
Bone Marrow Aspiration and Biopsy
It is used to diagnose blood cell disorders like anemias, leukemias and platelet disorders in conjunction with peripheral blood film findings.
They are also used for staging procedure in case of lymphomas and malignancies. It is usually done from posterior superior iliac spine. First of all aspiration is carried out followed by taking out a core of trabecular bone using a biopsy needle (Jamshidi needle).
Female Genital System
These can be in the form of endometrial currettings, endometrial biopsy, cervical biopsy, etc. It can help to diagnose a variety of menstrual disorders, inflammatory, precancerous and cancerous conditions.
Male Genital System
Besides tumors and infections, testicular biopsy plays an important role in assessing male infertility.
Most commonly transuretheral resection of prostate is performed. It can also be carried out through transrectal or transperineal route.
They are subjected to biopsy to determine signs of rejection or to check for recurrence of original disease.
Lesions of breast, lymphnode, muscle, skin, nerves, brain, etc can be subjected to biopsy for a definitive diagnosis.
Processing of Biopsy Material and Reporting
After retrieval, the sample of cells or tissue is preserved immediately in adequate 10% formalin or other appropriate fixative. This is then sent to a pathology laboratory where it is processed and representative, extremely thin slice of tissue material is obtained on glass slides.
Slides thus prepared are then treated with suitable dyes which differentially stain the nucleus and cytoplasm of the cells allowing the cellular details to be seen clearly.
These slides are then meticulously examined by a pathologist under a microscope.
The pathologist looks for any abnormal findings including the presence or absence of cancer (benign vs malignant lesion).
In case of cancer, its exact nature, classification, histological typing, grading and extent of spread including involvement of nerves or blood vessels are noted.
The status of margins which is defined as the distance between surgically resected margin and the tumor tissue is also determined. This is important to assess the possibility of recurrence and to decide whether further surgery or wider excision needs to be done.
- Positive margin (cancer cells present at the margin) indicates that the entire tumor has not been removed.
- A negative margin or clear margin (no tumor cells present at the margin) indicates that no residual tumor tissue is present in the vicinity and no further surgery is required.
- A close margin indicates that tumor cells are present very close to the resected margin – approximately 1 or 2 millimeters.
In some cases, additional tests like immunohistochemistry or cytogenetics may also be carried out along with routine testing on biopsy material. These provide additional information including receptor status and subtyping which play a role in determining the prognosis.
The pathology report thus prepared is then sent to the treating physician.
Time taken for biopsy reporting
A biopsy report usually takes 5-7 days to be prepared. If a particular case requires additional testing, more days are required for reporting. Bone biopsy requires a longer time since the bony tissue has to be decalcified prior to processing and sectioning.
What is Frozen Section Procedure in Biopsy?
Frozen section is a procedure in which microscopic analysis of the tissue is carried out rapidly within a few minutes after it is removed. Tissue is removed during surgery and a quick diagnosis is delivered while the patient is still on the operating table.
It is of use in surgeries like cancer surgery where a quick decision of whether the lesion is benign or malignant will guide whether further surgery is needed or not. The quality of slides produced by this method is inferior to those of routine biopsy. In some cases, the results may be inconclusive and final report is issued only after routine processing and embedding (which takes 5-7 days).
In spite of its technical limitations, frozen section is one of the important part of cancer treatment arsenal.
Types of Biopsies
Open Surgical Biopsy
It involves an incision in the skin by a surgeon to access the suspicious area.
Depending upon the site, it may be carried out under local or general anesthesia.
It can be of two types: Excisional or incisional.
In this, the entire lump or suspicious area is removed. This is especially carried out for small lesions. Besides providing diagnostic information, this procedure also serves as a definitive treatment for cases which turn out to be benign since no further treatment is required after complete removal of such lesions.
In this only a portion or small part of tissue is removed. This is performed in cases where the lesion is quite large or not fully accessible. The main purpose of this technique is to provide diagnostic information ie, whether the lesion is malignant or not and if so what is the histological type. This information is valuable to plan further mode of treatment. Depending upon the histological type of the tumor, chemotherapy, radiotherapy or complete surgical excision of the lesion is decided upon.
Core Biopsy or Needle Biopsy or Trucut Biopsy
It is a type of incisional biopsy. In this, a small amount of cylindrical tissue is removed using a larger “core” (meaning “hollow”) needle. It is a more invasive procedure than fine needle aspiration biopsy (FNAB), as it uses a thicker needle in comparison with FNAB and is carried out under local anesthesia.
However, it is quicker and less invasive than a surgical biopsy. In some cases, the result of a core biopsy will prevent the need for surgery to take place.
In this, a trianglular wedge shaped slice of tissue is removed. A small amount of normal tissue is also included.
This involves removal of a piece of tissue which is cylindrical or cone shaped. It is usually performed to diagnose cervical cancer. It can also be used as a form of treatment if cancer is small enough to be completely removed during biopsy.
It is a technique for obtaining skin biopsy samples. A circular blade is rotated down through the epidermis and dermis, and into the subcutaneous fat, yielding a 3- to 4-mm cylindrical core of tissue sample. It is used for lesions involving the dermis and subcutaneous tissue.
It is also used for skin biopsies. In this, the skin lesion and a thin layer of surrounding skin are removed with a small blade. It is used for superficial lesions which involve the epidermis only. It is quick, simple, cost-effective and does not require surgical sutures.
In this a fine needle (22 – 24 G) is used to obtain cellular material from the swelling. It is the least invasive biopsy procedure which is carried out without local anesthesia. It can be carried out in out-patients clinics or in pathology laboratories. Since the technique involves removal of cells without preserving their histological architecture, it should ideally be classified as a cytological technique and not a true biopsy. However both the terms are used interchangeably.
Image Guided Biopsy
Biopsy is carried out under the guidance of imaging technique such as computerized tomography (CT), magnetic resonance imaging (MRI) or ultrasound. This technique allows the doctor to ensure that the needle has reached the exact site which is intended to be biopsied.
Endoscopic, laproscopic , colonoscopic, colposcopic , thoracoscopic biopsies, etc are carried out through a scope inserted in various organs.
Liquid biopsy is a newer technique which is still in experimental stage. Cells or fragments of DNA from the tumor which are circulating in the blood or body fluids are collected and analyzed to give information about the tumors. It is non-invasive, painless, convenient and can be easily repeated. It has the potential to completely change the diagnostic tools of cancer in near future.
Where are Different Types of Biopsies Performed?
Less invasive biopsies like skin biopsies, bone marrow biopsies or FNABs can be performed in out-patient clinics or doctor’s office. The procedure is done with or without local anesthesia.
More invasive biopsies are usually done in a hospital setting or an operation theatre. It almost always requires sedation, local or general anesthesia. Pain relief medicines are also given after the procedure.
Risks and Complications of Biopsy Procedure
Less invasive biopsies in which a needle is inserted carry a lower risk of complication. More invasive biopsies involving a larger incision carry minor risk of infection or bleeding.