A biopsy involves extracting a small tissue sample from the suspected area to examine it closely under a microscope.
How are cancer cells detected?
Cancer cells look quite different from normal cells. They are often more primitive-looking and have oddly-shaped nuclei compared to a normal cell. Doctors can sometimes tell, from biopsies, where in the body a cancer has started.
Types of biopsies
Excisional Biopsy
This procedure involves the removal of an entire organ or lump. It has become less common since the development of fine needle aspirations; however it is still used for some types of tumors such as enlarged lymph nodes and breast lumps for a more accurate diagnosis.
Some organs such as the spleen are dangerous to cut into without complete removal, so excisional biopsies are also preferred in such cases.
Incisional Biopsy
This procedure involves only a partial surgical removal of a lump. It is most often used for tumors of the soft tissues like muscle, fat, and connective tissue to distinguish benign conditions from malignant soft tissue tumors, which are called sarcomas.
Endoscopic Biopsy
Likely the most commonly-performed type of biopsy, this procedure is done through a fiber optic endoscope that the doctor inserts into the body either through a natural body orifice or a small surgical incision. The endoscopist can directly visualize an abnormal area on the lining of the organ in question and pinch off tiny bits of tissue with forceps attached to a long cable that runs through the endoscope.
Colposcopic Biopsy
This is a gynecologic procedure that is typically used to evaluate patients who have abnormal areas on the cervix of the uterus, as shown by an abnormal Pap smear
Fine Needle Aspiration-FNA
This procedure is an extremely simple - it uses a technique where a needle no wider than that used to give routine injections is inserted into a tumor to draw up tens of thousands of cells. These cells are smeared on a slide and examined under a microscope by the pathologist to get a diagnosis within minutes.
Tumors of deep, hard-to-reach organs (pancreas, lung, and liver) are especially good candidates for FNA, as the only other way to sample them is through major surgery. Thyroid tumors are also excellent candidates for FNA, as a radiologist can perform it with the help of an ultrasound or CT scan. The procedure requires no anesthesia.
Punch Biopsy
This technique is typically used by dermatologists to sample skin rashes and small masses. After a local anesthetic is injected a biopsy punch, which is 3 or 4 mm in diameter, is used to cut out a piece of skin. The hole is typically closed with a stitch and heals with minimal scarring.
Bone Marrow Biopsy
In cases of abnormal blood count (such as unexplained anemia), high white cell count, and low platelet count, it is necessary to examine the cells of the bone marrow. The sample is usually taken from bone on either side of the pelvis.