There are not many who have not heard of biopsy. Some seem to add a tinge of fear to the word, especially for people whose near and dear ones has to undergo it. For a common man, biopsy is a test for determining cancer and as soon as they are ordered to get a biopsy done, some kind of tremble that they have got cancer. ‘Bio’ means living and ‘opsy’ means viewing. Thus biopsy could be said as ‘testing living tissues and determining if any disease exists or the level of the disease. The earliest biopsy techniques are said to be developed by Abulcasis in the 11th century. It was the invention of Microscope that transformed the technique of biopsy to the current heights. The term’s way in to medical dictionary began with Ernest Besnier - the French dermatologist - coining the term biopsy.
We know human body is made up of several trillion cells. Each part of the body has cells which are specialized and adapted to carry out definitive functions of that part of the body. The mechanisms and behavior of these cells and changes if any are analysed with a microscope to find out any abnormalities and if it is affected by a disease.
Biopsy – What and Why?
A biopsy is taking and analyzing a specimen of tissues of a body part which is suspected to have a disease. Let’s take a look at some of the circumstances that necessitates a biopsy.
Biopsy is done for functions such as determining if a new lump in the breast is cancer, checking if the swelling of the neck is because of TB, etc. For patients who have bleeding per rectum especially in old aged, a tissue specimen is taken from the colon by doing a colonoscopy examination and biopsy is carried out to determine whether it is due to hemorrhoids, cancer, or something else.
Scan, blood tests, or clinical examination are used in the preliminary methods to determine a disease. However, for 100% confirmation a biopsy is mostly necessary. For example, intestinal cancers, thyroid tumors, etc. Even though most of the skin diseases can be determined just by checking the skin, the accuracy of this can be done through a biopsy - Psoriasis is one example of this. Commonly used other type of biopsies include nerve and muscle biopsies.
Biopsy enables not just determining the disease, but also the nature of the disease. Only then appropriate treatment modalities can be given. Hence, biopsy is most often necessitated.
Pathologists are able to gauge the nature and intensity of the disease with a biopsy. As per this report, treating doctor can determine the best possible treatment regimen for the patients and also predict to an extent its response in controlling the disease. This will help them in keeping the relatives appropriately informed. Especially in cancer treatment, this provides many benefits.
Biopsy enables to specify the disease and exclude others. If you take the swelling of the neck, it could be due to a viral fever, due to infection of the throat, a symptom of TB, due to leukemia, due to cancer of some other organ, etc. It takes a single biopsy to determine the exact cause of the swelling.
Biopsy – How?
Mainly two methods are used to diagnose a disease through biopsy. Cytopathology – wherein the particular cells are individually analysed for its nature, change in architecture and end in a conclusion. The second is Histopathology, in which tissue is taken as a whole and evaluate.
Based on the part of body tested, there are different methods for cytology examination. FNAC or Fine Needle Aspiration Cytology is a familiar one for many. With this, cells from a lump or swelling is taken with a small needle and analysed. Many patients would have seen tissues being aspirated with a needle from the lump in breast or swelling in the thyroid gland and taken in a glass slide. Cervical cancer is also diagnosed many times with a Pap smear – which again is a cytological biopsy. For this, a device resembling an ice cream scoop is used to scrub the cells, which is put on glass slide along with special colors - Papanicolaou Stain (shortened as Pap smear) – and analysed through a microscope. This enables viewing the nucleus, cytoplasm, and other parts of the cell clearly and making the diagnosis.
The advantages of cytological examination include the easiness of doing it, the short time for making a diagnosis (1-2 days), and lower cost. Hence, doctors consider cytological examination as a first step of examination in most of the cases. However, the limitations in determining treatment modalities with cytological examination make histopathological examination a necessity.
Surgically removed or wide bore needle aspirated samples from disease suspected body parts are taken for analysis in this form of biopsy technique. Various methods are available for this. For example, if a lump is affecting the intestine, the lump with some normal tissues on both ends of the lump is taken and analysed – this is called resection biopsy. If a small part of a nonhealing ulcer is cut and taken for analysis, it is called wedge biopsy. If a lump is removed entirely and examined, it is excision biopsy. When only a part of it is removed, it is called incision biopsy. Core biopsy is using a large needle to pierce the lump and take small parts for examination.
Radiological techniques such as CT or ultrasound scans are used for assisting doctors for taking biopsy examination of lumps or diseased areas which are difficult to access. For example small lumps in the thyroid glands which cannot be identified on normal palpation require ultrasound-guided FNAC. Similarly in CT guided biopsy, by seing the lesion via CT scan a sample can be taken from organs such as lungs or brain.
The specimens collected are sent to the pathology lab in a bottle filled with formalin (10% formaldehyde) with patient details.
These specimens are taken through various stages of analysis by expert pathologists. The sample tissues are taken from the formalin and cut in to small pieces which are shifted to small plastic cassettes and packed with paraffin wax. Now it is a tissue block. Using a Microtom, this block is sliced in to sheets of 5 microns (each micron is a thousandth of a millimeter). Each sheet is taken in a glass slide and stained with colored liquids like Eosin and Hematoxylin. Analysing this with a microscope a diagnosis is made.
Even though this examination process takes at least a week, the diagnosis is reliable. For diseases like cancer, this is very important.
The benefit of histopathological examination is not just disease diagnosis. If it is cancer, the type (carcinoma, sarcoma, melanoma, lymphoma, etc.), the grade (low grade/high grade or grade 1, 2, 3, 4), tissue differentiation (well, moderate or poor), whether the cancer has invaded into vascular or perineural areas, whether the surgery is complete (negative resection margins), etc. are determined through this examination. These factors influence the future treatment modalities significantly.
Now you know that biopsy is not just for diagnosing cancer. Right from acne to hemorrhoids, baldness to corns and calluses, TB to arthritis – the cause for any disease can be determined with a biopsy. The use of special stains and the advent of Immunohistochemistry has accelerated disease diagnosis through biopsy. It is a field where high professional skills, expertise, technological assistance and extreme efforts are required.