Lung biopsy is a medical procedure performed to obtain a small piece of lung tissue for examination under a microscope. Biopsy examinations are usually performed by pathologists, who are doctors with special training in tissue abnormalities and other signs of disease.
Lung biopsies are useful, first of all, in confirming a diagnosis of cancer, especially if malignant cells are detected in the patient's sputum. A lung biopsy may be ordered to examine other abnormalities that appear on chest x rays, such as lumps (nodules). It is also helpful in diagnosing symptoms such as coughing up bloody sputum, wheezing in the chest, or difficult breathing. In addition to evaluating lung tumors and their associated symptoms, lung biopsies can be used in the diagnosis of lung infections, especially tuberculosis, drug reactions, and such chronic diseases of the lung as sarcoidosis.
A lung biopsy can be used for treatment as well as diagnosis. Bronchoscopy, which is a type of lung biopsy performed with a long slender instrument called a bronchoscope, can be used to clear a patient's air passages of secretions and to remove blockages from the airways.
As with any other biopsy, lung biopsies should not be performed on patients who have problems with blood clotting because of low platelet counts. Platelets are small blood cells that play a role in the blood clotting process. If the patient has a platelet count lower than 50,000/cubic mm, he or she can be given a platelet transfusion as a temporary relief measure, and a biopsy can then be performed.
The lungs are a pair of cone-shaped organs that lie in the chest cavity. An area known as the mediastinum separates the right and the left lungs from each other. The heart, the windpipe (trachea), the lymph nodes, and the tube that brings the food to the stomach (the esophagus) lie in this mediastinal cavity. Lung biopsies may involve entering the mediastinum, as well as the lungs themselves.
Types of lung biopsies
Lung biopsies can be performed using a variety of techniques. A bronchoscopy is ordered if a patch that looks suspicious on the x ray seems to be located deep in the chest. If the area lies close to the chest wall, a needle biopsy is often done. If both these methods fail to diagnose the problem, an open surgical biopsy may be carried out. If there are indications that the lung cancer has spread to the lymph nodes in the mediastinum, a mediastinoscopy is performed.
NEEDLE BIOPSY. When a needle biopsy is to be done, the patient will be given a sedative about an hour before the procedure, to help relaxation. The patient sits in a chair with arms folded on a table in front of him or her. X rays are then taken to identify the location of the suspicious areas. Small metal markers are placed on the overlying skin to mark the biopsy site. The skin is thoroughly cleansed with an antiseptic solution, and a local anesthetic is injected to numb the area.
The doctor then makes a small cut (incision) about half an inch in length. The patient is asked to take a deep breath and hold it while the doctor inserts the special biopsy needle through the incision into the lung. When enough tissue has been obtained, the needle is withdrawn. Pressure is applied at the biopsy site and a sterile bandage is placed over the cut. The entire procedure takes between 30 and 45 minutes.
The patient may feel a brief sharp pain or some pressure as the biopsy needle is inserted. Most patients, however, do not experience severe pain.
OPEN BIOPSY. Open biopsies are performed in a hospital under general anesthesia. As with needle biopsies, patients are given sedatives before the procedure. An intravenous line is placed in the arm to give medications or fluids as necessary. A hollow tube, called an endotracheal tube, is passed through the throat, into the airway leading to the lungs. It is used to convey the general anesthetic.
Once the patient is under the influence of the anesthesia, the surgeon makes an incision over the lung area. Some lung tissue is removed and the cut closed with stitches. The entire procedure usually takes about an hour. A chest tube is sometimes placed with one end inside the lung and the other end protruding through the closed incision. Chest tube placement is done to prevent the lungs from collapsing by removing the air from the lungs. The tube is removed a few days after the biopsy.
A chest x ray is done following an open biopsy, to check for lung collapse. The patient may experience some grogginess for a few hours after the procedure. He or she may also experience tiredness and muscle aches for a day or two, because of the general anesthesia. The throat may be sore because of the placement of the hollow endotracheal tube. The patient may also have some pain or discomfort at the incision site, which can be relieved by medication.
MEDIASTINOSCOPY. The preparation for a mediastinoscopy is similar to that for an open biopsy. The patient is sedated and prepared for general anesthesia. The neck and the chest will be cleansed with an antiseptic solution.
After the patient has been put to sleep, an incision about two or three inches long is made at the base of the neck. A thin, hollow, lighted tube, called a mediastinoscope, is inserted through the cut into the space between the right and the left lungs. The doctor examines the space thoroughly and removes any lymph nodes or tissues that look abnormal. The mediastinoscope is then removed, and the incision stitched up and bandaged. A mediastinoscopy takes about an hour.
Before scheduling any lung biopsy, the doctor will check to see if the patient is taking any prescription medications, if he or she has any medication allergies, and if there is a history of bleeding problems. Blood tests may be performed before the procedure to check for clotting problems and blood type, in case a transfusion becomes necessary.
If an open biopsy or a mediastinoscopy is being performed, the patient will be asked to sign a consent form. Since these procedures are done under general anesthesia, the patient will be asked to refrain from eating or drinking anything for at least 12 hours before the biopsy.
Following a needle biopsy, the patient is allowed to rest comfortably. He or she will be checked by a nurse at two-hour intervals. If there are no complications after four hours, the patient can go home. Patients are advised to rest at home for a day or two before resuming regular activities, and to avoid strenuous activities for a week after the biopsy.
Open biopsy or mediastinoscopy
After an open biopsy or a mediastinoscopy, patients are taken to a recovery room for observation. If no other complications develop, they are taken back to the hospital room. Stitches are usually removed after seven to 14 days.
If the patient has extreme pain, light-headedness, difficulty breathing, or develops a blue tinge to the skin after an open biopsy, the doctor should be notified immediately. The sputum may be slightly bloody for a day or two after the procedure. If, however, the bleeding is heavy or persistent, it should be brought to the attention of the doctor.
Needle biopsy is a less risky procedure than an open biopsy, because it does not involve general anesthesia. Very rarely, the lung may collapse because of air that leaks in through the hole made by the biopsy needle. If the lung collapses, a tube will have to be inserted into the chest to remove the air. Some coughing up of blood occurs in 5% of needle biopsies. Prolonged bleeding or infection may also occur, although these are very rare.
Possible complications of an open biopsy include infection or lung collapse. Death occurs in about 1 in 3000 cases. If the patient has very severe breathing problems before the biopsy, breathing may be slightly impaired following the operation. If the person's lungs were functioning normally before the biopsy, the chances of any respiratory problems are very small.
Complications due to mediastinoscopy are rare; death occurs in fewer than 1 in 3000 cases. More common complications include lung collapse or bleeding caused by damage to the blood vessels near the heart. Injury to the esophagus or voice box (larynx) may sometimes occur. If the nerves leading to the larynx are injured, the patient may be left with a permanently hoarse voice. All of these complications are very rare.
Normal results of a needle biopsy and an open biopsy include the absence of any evidence of infection in the lungs. No lumps or nodules will be detected in the lungs and the cells will not show any cancerous abnormalities. Normal results from the mediastinoscopy will show the lymph nodes to be free of cancer.
Abnormal results may be associated with diseases other than cancer. Nodules in the lungs may be due to active infections such as tuberculosis, or may be scars from a previous infection. The lung cells on microscopic examination do not resemble normal cells, and show certain abnormalities that point to cancer. In a third of biopsies using a mediastinoscope, the lymph nodes that are biopsied prove to be cancerous. Abnormal results should always be considered in the context of the patient's medical history, physical examination, and other tests such as sputum examination, chest x rays, etc. before a final diagnosis is made.
Bronchoscopy — A medical test that enables the doctor to see the breathing passages and the lungs through a hollow, lighted tube.
Endotracheal tube — A hollow tube that is inserted into the windpipe to administer anesthesia.
Lymph nodes — Small, bean-shaped structures scattered along the lymphatic vessels which serve as filters. Lymph nodes retain any bacteria or cancer cells that are traveling through the system.
Mediastinoscopy — A medical procedure that allows the doctor to see the organs in the mediastinal space using a thin, lighted, hollow tube (a mediastinoscope).
Mediastinum — The area between the lungs, bounded by the spine, breastbone, and diaphragm.
Sputum — Mucus or phlegm that is coughed up from the passageways (bronchial tubes) in the lungs.
American Cancer Society. 1599 Clifton Rd., NE, Atlanta, GA 30329-4251. (800) 227-2345. http://www.cancer.org.
American Lung Association. 1740 Broadway, New York, NY 10019. (800) 586-4872. http://www.lungusa.org.
Cancer Research Institute. 681 Fifth Ave., New York, N.Y. 10022. (800) 992-2623. http://www.cancerresearch.org.
National Cancer Institute. Building 31, Room 10A31, 31 Center Drive, MSC 2580, Bethesda, MD 20892-2580. (800) 422-6237. http://www.nci.nih.gov.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.