Peritoneal Mesothelioma

Malignant peritoneal mesothelioma is an extremely rare cancer. Only 100 to 500 cases are diagnosed in the US each year, making up less than 30% of all mesothelioma cases. Peritoneal mesothelioma is a cancer affecting the abdominal lining, or peritoneum (paira-tin-e-um), which is why is is sometimes referred to as abdominal mesothelioma. This membrane supports and covers the organs of the abdomen.

The peritoneum is made of two parts, the visceral and parietal peritoneum. The visceral peritoneum covers the internal organs and makes up most of the outer layer of the intestinal tract. Covering the abdominal cavity is the parietal peritoneum. Cells in these linings secrete a fluid which allows organs to move against one another. For instance, as the intestines move food through the body. The cells of the mesothelium are designed to create fluid, but the cancer can cause them to overproduce, creating a build up of excess fluid in the abdominal cavity…..

diagnosisBecause pleural mesothelioma is more common and often spreads to the peritoneal cavity, it is important to etermine if pleural mesothelioma is the primary cancer.

Although there’s no definitive explanation, it is widely believed that asbestos causes peritoneal mesothelioma in one of two ways. First, asbestos fibers may be ingested, and when in the intestinal tract, the fibers may work themselves into the peritoneal cavity and peritoneum. Second, they may be inhaled and transported through the lymph node system to the peritoneal cavity.

If you are wondering “do I have peritoneal mesothelioma?” you should seek the guidance of your physician immediately; like many cancers, early detection is very important. Malignant peritoneal mesothelioma symptoms may not appear until 20 to 30 years after the first exposure to asbestos. Symptoms are usually not specific to peritoneal mesothelioma, and most often accompany other, less serious medical issues. This may make diagnosing peritoneal mesothelioma more difficult. If you have a history of asbestos exposure, your should have regular check ups with your doctor and an awareness of peritoneal mesothelioma symptoms.

Ascites is the abnormal collection of fluid in the abdomen; when it is caused by cancer, it is referred to as malignant ascites. A cancer diagnosis is only made in about 10% of ascites cases, and of that 10%, peritoneal mesotheioma makes up only a very small percentage. Ascites can be quite uncomfortable, causing swelling of the abdomen, weight gain, indigestion, nausia, and swelling of the feet and ankles.

Fluid retention usually causes swelling; solid tumor masses may be responsible for pain. Despite the accumulated fluid, which often increases waist size, a patient’s appetite may be aversely affected by peritoneal mesothelioma resulting in weight loss.  Bowel obstruction: A blockage in the small or large intestine is a rare, and often late-occuring, symptom of peritoneal mesothelioma. Anemia:  A reduction in the number of red blood cells to below normal; this forces the heart and other organs to work harder to get oxygen where it’s needed. Fever: Infection is the most common cause of fever in cancer patients, but tumor cells can also produce fever-causing agents. A bowel obstruction may also cause fever.

Symptoms of peritoneal mesothelioma are not necessarily unique to the disease, so diagnosing peritoneal mesothelioma requires more than an observation of symptoms. Most symptoms associated with abdominal mesothelioma accompany other, often less serious, medical conditions. Most peritoneal mesothelioma diagnoses are made when the malignancy is in an advantage stage and diagnosis, alone, takes on average four months1.

The first step in diagnosing peritoneal mesothelioma is a physical exam and patient history. If your doctor does not ask about your work history and potential mesothelioma risk factors, let him or her know about your asbestos exposure. A history of asbestos exposure is an important clue for your physician or diagnostician and neglecting to mention this could delay diagnosis.

Following a physical exam and a patient’s description of their symptoms, the next step in diagnosing peritoneal mesothelioma is usually to get some type of imaging of the abdomen. An x-ray, CT (or CAT) scan, or MRI may be performed. Although mesothelioma cannot be definitively diagnosed by visual confirmation, tumors may be visible, or an excess of serous fluid may be seen. The three primary types of peritoneal mesothelioma tumor development seen are:

The most common of peritoneal mesothelioma presentations, one large or several small but similarly located peritoneal masses are seen.“Wet”Associated with ascites and swelling, no solid masses but small nodules and plaques are visible in this type of peritoneal mesothelioma.“Mixed”A combination of both “wet” and “dry” types of peritoneal mesothelioma.

In cases where fluid has accumilated in the abdomen, paracentesis may be performed; a needle is inserted into the peritoneal cavity to drain the excess fluid from the abdomen. Usually, cytologic testing on this ascetic (peritoneal) fluid (where specialists examine the fluid for abnormal cells) is not considered effective to diagnose peritoneal mesothelioma.

The next step in effectively diagnosing peritoneal mesothelioma is the collection of a biopsy. A biopsy is required so that the tissues and cells in question can be examined at a microscopic level. A fine-needle aspiration biopsy is usually performed at first because they are minorly invasive and quite safe. Immunohistochemical staining of the biopsy is regularly performed on collected samples. Sometimes referred to casually as “immunos,” these tests use special substances that color proteins and markers that indicate cancerous cells.

Sometimes further testing is required to make a definitive diagnosis, whether because the initial biopsy testing was inconclusive or a fine-needle biopsy could not be taken because of the location of the tumor and/or fluid pockets. If this is the case, the next step performed is often a peritoneoscopy. During this procedure, a local anesthetic is administered and a small incision allows the doctor looks inside the abdomen with a special tool called a peritoneoscope.

During the peritoneoscopy, a larger biopsy sample may be collected for testing. Finally, if more tissue is required for testing, diagnositic surgery or “open” biopsy may be required.

Diagnosing peritoneal mesothelioma is very difficult, and cases of peritoneal mesothelioma misdiagnosed or undiagnosed are unfortunately not uncommon. It is important to share your case history of work experience (especially in shipyards and at construction sites) and asbestos exposure potential with your physicians if you feel mesothelioma is a risk. Asbestos fibres can also be carried into the home on clothing, inadvertently exposing the deadly fibres, and the risk of mesothelioma, to family members.

In addition to determing a diagnosis, many diagnostic test also help determine the stage the cancer is in, providing a better idea of a patient’s prognosis. The chance of recovery depends on the size of the cancer, where the cancer is, how far the cancer has spread, how the cancer cells look under the microscope, how the cancer responds to treatment, and the patient’s age. Peritoneal mesothelioma is usually diagnosed when it has had time to advance; as with most types of cancer, early diagnosis is an excellent first step in fighting the disease.