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Diagnosing mesothelioma begins with your first visit to the doctor after you notice symptoms. Typically, the process begins with a routine physical exam and a discussion of medical history with a general practitioner. The next steps include imaging the lungs and pleura to look for potential tumors. Imaging is usually followed by biopsies to confirm the presence of tumors and cancer cells.
A biopsy is an important step, not only in diagnosing mesothelioma, but also in staging it. When biopsy cells are examined, a pathologist may be able to determine not only if the cells are cancerous, but also what type of cancer is present. Sometimes diagnosing mesothelioma can be difficult because it so rare. Other times not enough cells are removed from an original biopsy for the pathologist to give a firm diagnosis. In those cases, they will repeat the biopsy.
What is a Biopsy?
A biopsy is the examination of a fluid or tissue sample for the purpose of diagnosing a condition. Medical professionals also use biopsies to find the source of an illness and determine its extent. A biopsy can confirm the presence of cancerous cells, reveal the types of cancer cells, and show how if and far the cancer has spread depending on where the biopsy is taken from.
A tissue or fluid sample is extracted with a needle, with open surgery, or with an endoscope. A pathologist examines the samples under a microscope to learn about the tissue, cells, and fluid.
The Importance of Biopsies in Diagnosis
A biopsy is one part of a complete diagnosis for mesothelioma. It is the most accurate way to confirm someone actually has mesothelioma. An imaging test can tell a doctor that there is some type of tumor in the pleura or other area of the body. However, imaging cannot confirm suspected tissues are malignant or determine the specific type of cancer. Biopsies also determine the extent of the cancer. All of this information helps the patient and medical team develop the best possible treatment plan.
Image Guided Biopsies
Patients with suspected cancer will first undergo imaging studies, which will help guide doctors to the best location to biopsy. Most often, this includes a biopsy guided by additional imaging, to be sure the needed is going into the correct area. This can be done via ultrasound or CT guidance. Given the nature of mesothelioma, this is usually done with a CT guided biopsy performed in an outpatient area in a hospital setting. The doctor is able to use the images to directly see where the needle is taking a biopsy.
Fluid and Needle Biopsies
Testing fluid that builds up during mesothelioma can be a useful part of the diagnosis. When pleural mesothelioma is suspected, fluid is taken from the pleural cavity for testing. This procedure is called a thoracentesis. A paracentesis removes fluid from the abdomen to test for peritoneal mesothelioma. A pericardiocentesis removes fluid from the sac around the heart to test for pericardial mesothelioma. These are done by ultrasound or CT guidance depending on the situation.
Although not as common, some superficial biopsies may be performed if there are lesions visible to the eye. These are not considered invasive. This procedure can typically be performed in a doctor’s office with local anesthetic. A small needle is inserted through the skin to the area of fluid buildup. Then a small amount of fluid is removed for testing. The fluid is examined under a microscope to look for cancer cells. In addition to fluid, a tissue sample may also be taken.
An endoscope is a thin, flexible tube used to examine inside the body. The endoscope has a light as well as a lens or a camera that allows the doctor to see deep into the body. Although procedure is relatively noninvasive and does not require a large incision or open surgery, it does require it to be done in a monitored space. This can be in a diagnostic space, similar to where people have outpatient colonoscopies, for example. Or in the operating room if general anesthesia is required.
Because most cases of mesothelioma are pleural, biopsies for mesothelioma may require a thoracoscopy. This is a type of endoscopy that is inserted into the chest to examine the pleura and suspected tumors. During the procedure, a biopsy of the pleura is removed. This provides more tissue for the pathologist to examine to confirm the diagnosis or provide additional information. Although less invasive than open surgery, an endoscope biopsy like this still requires the patient be under general anesthesia.
Less invasive and lower risk techniques for biopsies are always used first. However, sometimes they are not enough to diagnose mesothelioma. As a last resort, doctors will conduct open surgery. Open surgery uses an incision to remove a significant amount of tissues. Video assisted thoracic surgery (VATS) is a minimally invasive approach and uses small incisions and a camera to obtain a biopsy. A thoracotomy is a larger incision along the chest and performed during complex surgeries. A laparotomy is the same procedure through the abdomen and is used for diagnosing peritoneal mesothelioma.
Incisional and Excisional Biopsies
Biopsies for mesothelioma are also sometimes classified as incisional or excisional. For an incisional biopsy, only a small amount of tissue is removed from a tumor. These are done when the tumor is easily accessible. An excisional biopsy refers to the entire removal of a tumor. If possible, doctors will remove an entire mass, both for testing and as a part of treatment. This procedure is like killing two birds with one stone. It allows for a biopsy of the tumor and negates the need for later surgical removal.
There are many types of biopsies. The type you may undergo for mesothelioma diagnosis depends on individual factors. Your medical team will decide which biopsies are necessary for accurate diagnosis. From there they will set you on a path to treatment.
Page Medically Reviewed and Edited by Anne Courtney, AOCNP, DNP
Anne Courtney has a Doctor of Nursing Practice degree and is an Advanced Oncology Certified Nurse Practitioner. She has years of oncology experience working with patients with malignant mesothelioma, as well as other types of cancer. Dr. Courtney currently works at University of Texas LIVESTRONG Cancer Institutes.