Why are samples taken in research?
Biopsy: taking a tissue sample
Biopsy - what is it?
As a rule, a biopsy is an option if the doctor has felt or seen an increase in tissue. Or a marker in the blood has changed noticeably. A focus of the disease may also be visible after an imaging examination, which raises questions. In many cases, only examination of the tissue obtained under the microscope will clarify whether the focus is a benign growth or a malignant cancer. Parts of the suspicious area or the entire change are removed using different methods.
If certain clinical pictures are suspected, several biopsies can be taken from one organ. An example of this are punch biopsies of the prostate.
What can be biopsied?
Biopsies can affect almost any organ. Here are some types of biopsy as an example, each with a typical reason for the procedure:
- Skin biopsy: abnormal birthmark
- Muscle biopsy: if the muscle disease is unclear
- Lymph node biopsy: if the magnification is unclear with suspicion of malignancy
- Bone marrow biopsy: for disorders of blood formation
- Brain biopsy: suspected brain tumor or focus of inflammation
- Thyroid biopsy: ultrasound detected lump
- Lung biopsy: an unclear round focus discovered by an imaging examination
- Breast biopsy: if there is a lump in the breast
- Stomach biopsy: changes in the mucous membrane visible in the gastroscopy
- Liver biopsy: if the liver disease is unclear and suggests that the liver tissue has been remodeled
- Kidney biopsy: after a kidney transplant to check for rejection reactions
- Small intestine biopsy: suspected celiac disease
- Intestinal biopsy: visible growth of the mucous membrane during a colonoscopy
- Bladder biopsy: an abnormality detected by mirroring the bladder
- Prostate biopsy: clarification of a suspected tumor
- Uterine scraping: in the event of a menstrual disorder
Classification according to the extent of the biopsy
If the doctor cuts or pricks into a focus of the disease and only removes part of the tissue, he speaks of an incisional biopsy (incision = incision). For example, if a so-called soft tissue sarcoma (malignant tumor) is suspected, surgeons often perform an incisional biopsy on the arms or legs. The same applies to muscle biopsies, in which only a small proportion of fibers is removed as carefully as possible.
The complete removal of a focus of the disease is an excisional biopsy (excision = section).
Excisional biopsies are, for example, the removal of a polyp in the intestine by means of a colonoscopy and the complete removal of a mole or an enlarged lymph node. In the case of a so-called conization, the doctor also removes a cone of tissue from the cervix with complete precancerous stages and early tumor stages.
Depending on the instrument the doctor uses to perform the biopsy, there are different names for the biopsies. The doctor often checks biopsies performed with a needle with a simultaneous imaging method, for example ultrasound.
These instruments are used:
Fine needle biopsy (FNB)
The doctor punctures suspicious lumps with a syringe and a needle that is up to 0.75 millimeters thick. Due to the very thin needle, this sampling can be compared to taking blood and, in contrast to a punch biopsy, anesthesia can usually be dispensed with. Through the attached syringe, the doctor creates negative pressure, as if taking a blood sample, and extracts individual cells from the target area. With a fine needle, the following organs are often punctured from the outside using ultrasound control:
During an endoscopy (mirroring the organs from the inside), an ultrasound can also be performed and, under this control, a biopsy of the following organs can be made from the inside:
The needles used in a punch biopsy are up to 2.2 millimeters thick. This usually requires a local anesthetic. The examiner can use a punch biopsy to obtain tissue cylinders from which the laboratory doctor later makes thin sections and examines them under the microscope. Doctors use punch biopsies for these organs, among others:
- Mammary gland
High speed punch biopsy
Doctors use this sophisticated technique to treat lumps in the female breast that are visible on ultrasound. The punch needle consists of a solid needle with a two centimeter long side recess and a ground hollow needle that surrounds the solid needle. With a releasable mechanism, the solid needle shoots into the knot first, and tissue from the knot falls into the recess. Then the hollow needle shoots forward and separates the tissue in the recess.
The special thing about the vacuum biopsy is the up to 4 millimeter thick "windowed" hollow needle with a lateral opening. As soon as the needle is in the target area, the doctor applies suction, which sucks tissue into the needle through the opening on the side. A rotating knife then cuts the tissue inside the needle. Doctors use the vacuum biopsy, for example
- the mammary gland
- and the prostate
Biopsy by surgery
If you have cancer, it is often important to remove and examine the nearest lymph nodes in the lymphatic drainage area. The laboratory then uses a microscope to determine whether cancer cells have already established themselves there. The doctor completely removes these lymph nodes as part of an operation (also called lymph node extirpation). In almost all tumor operations there are now guidelines as to how many lymph nodes must be removed from which adjacent areas at least so that the so-called tumor stage can be determined and thus the further therapy can be determined (for example, this often decides whether chemotherapy has to follow the operation ). Breast cancer has a special lymph node (sometimes several that have this function), the sentinel lymph node. It lies in the armpit of the affected side and can be marked with dye before the operation and then punctured. Or during the operation, the marked lump is completely removed and sent to the pathologist for a quick examination. If the sentinel lymph node is not affected, the axillary lymph nodes usually do not need to be removed during the operation. This not only saves time, it also saves the patient unnecessary additional surgery and pain.
The doctor uses biopsy forceps with two handles. By squeezing the handles, the doctor snaps off tissue with the tip of the forceps. Special biopsy forceps can also be passed through an endoscope and take tissue samples deep in the body. There are forceps biopsies, for example, in the area
- the lungs
- of the stomach
- and the intestines.
During curettage, the doctor uses sharp-edged scrapers, so-called curettes. He uses it to remove the mucous membrane or skin. Examples are the scraping of the uterus and the collection of skin samples in the case of fungal diseases of the skin.
Cell smear or brush cytology
Particularly fine brushes or small spatulas are used here for the extraction of individual cells in very narrow spaces. For example, as part of early cancer detection, the doctor can extract cells from the mucous membrane of the cervix. Or material is obtained from very thin ducts, as can be the case, for example, with an endoscopic examination of the pancreas or bile ducts. These cells are then transferred to a slide. Sometimes, however, these examinations are also unsuccessful, as only very little material is removed and you can only see under the microscope whether there are any changed cells.
Examination of the biopsy
A specialized laboratory examines the tissue sample after it has been removed. If it is a larger piece of tissue, the specialist in tissue examinations, the so-called pathologist, first cuts it into fine layers and stains them. Then he looks at the layers under the microscope. The type of cells gives him clues as to which organ the sample comes from. He can also see whether the tissue is benign or malignant, i.e. cancer. If it is cancer, the examination can usually also show whether the tumor has arisen at this point, whether it is a metastasis of a tumor from a completely different region of the body.
Depending on how much the cancer cells differ from the original tissue and which section of the tumor was affected, the pathologist can also make a statement about the properties of the tumor, for example how aggressively it grows into other tissue.
Molecular biological tests can also show in some types of cancer whether the cells have certain receptors that make them vulnerable to anti-cancer drugs.
Biopsies are usually minimal and low-risk procedures. Minor bleeding or bruising can occur at the location of the collection. To rule out infections from the biopsy, doctors sometimes give patients an antibiotic as a precautionary measure. Other possible dangers depend on the location of the biopsy and whether an anesthetic (short anesthetic) was required.
In the vast majority of tumor types, studies have shown that there is no risk of individual tumor cells being carried over by the biopsy. An example of an exception is soft tissue sarcoma. With them, it is necessary to take precautionary measures: During a biopsy, the actual puncture needle is withdrawn through an enveloping guide needle so that individual tumor cells cannot get stuck in the puncture canal. In addition, the doctors choose the puncture canal in such a way that they can remove it if necessary during a subsequent operation on the tumor.
1. German Cancer Research Center Cancer Information Service: Biopsy: This is how tissue samples are taken. Online: www.krebsinformationsdienst.de/untersprüfung/biopsie.php Breast cancer surgery Online: https://www.krebsinformationsdienst.de/tumorarten/brustkrebs/operation.php#inhalt17 (accessed on May 14, 2019)
2. BAO Bundesverband für Ambulantesoperieren eV: - Tissue removal from the cervix (conization) Online: https://www.operieren.de/content/e3224/e10/e886/e898/e935/ - Removal of skin and soft tissue tumors Online: https: //www.operieren.de/e3224/e10/e451/e456/e537/ - muscle biopsy online: https://www.operieren.de/e3224/e10/e451/e456/e9469/ (accessed on 14.05.2019)
3. Prostate Help Germany: Is a biopsy really necessary? Online: https://prostata-hilfe-deutschland.de/biopsie-real-notwendig/ (accessed on May 14, 2019)
4. Schenk, Maren: HPV-Related Carcinomas and Genital Warts: Ways to Effective Prevention 115 (43): A-1948 / B-1627 / C-1612
5. Role of endoscopy in primary sclerosing cholangitis: European Society of Gastrointestinal Endoscopy (ESGE) and European Association for the Study of the Liver (EASL) Clinical Guideline.
J Hepatol. 2017 Apr 13. pii: S0168-8278 (17) 30108-3. doi: 10.1016 / j.jhep.2017.02.013.
6. German Society for Senology: Sentinel-Node-Biopsy in breast cancer Interdisciplinary agreed consensus of the German Society for Senology for quality-assured application in clinical routine. Online: https://www.senologie.org/fileadmin/media/documents/pdf/konsensuspapier_sentinel.pdf (accessed on May 14, 2019)
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