Symptoms of Mesothelioma

The diagnostic path involves a series of steps, including the accurate collection of data relative to the medical and occupational history of the patient (anamnesis), a visit with a physician and the implementation of instrumental exams. The latter include both imaging techniques and more or less invasive surgical interventions, vital not only for diagnostic purposes but also because they can offer valuable information on the extension and exact nature of the tumor.

Collection of anamnesis and objective examination
At this stage, the physician’s goal is to discover possible symptoms and risk factors. He/she will ask the patient questions about his/her profession, lifestyle habits, clinical history and his/her current health condition. The objective examination (otherwise called the general “visit”) offers information on the possible signs of the illness. A subject affected by pleural mesothelioma might show the presence of a pleural effusion, while an ascites or a palpable abdominal mass may be signs of a peritoneal mesothelioma.

Imaging techniques
Among the most popular techniques used are regular x-rays, CAT scans (computerized axial tomography) and NMRs (nuclear magnetic resonance)

Chest X-rays can offer information about pathological alterations caused by exposure to asbestos, already in the process of becoming a tumor. Chest X-rays can, for example, detect the presence of a pleural effusion, areas of calcification, irregular thickening of the pleurae, and thinning of the fissure between the pulmonary lobes.

CAT scans and NMRs offer a series of detailed images of selected areas of the body. They allow for the detection of masses, their extension and relation to surrounding structures. A CAT scan can also be performed in conjunction with a so-called contrast medium; a substance that injected in a patient’s vein, distributes itself in the tissues, allowing for a higher quality of imaging and increased accuracy. Imaging techniques are therefore essential in both the diagnostic and subsequent staging phase. Nevertheless, they do not offer information on the histological characteristics of a tumor, which are sometimes the only way to differentiate various types of tumors. For example, a diagnostic doubt could arise between a mesothelioma, a pulmonary carcinoma or a sarcoma. Diagnostic certainty is only obtained through a biopsy or a surgical exploration.

Invasive procedures
In order to confirm the diagnosis of MMe, it is necessary to conduct a biopsy, or in the case of a pleural effusion or ascites, to take and examine a small fluid sample.

In patients with a pleural effusion, a sample of such fluid can be obtained through thoracocentesis, a technique whereby a needle is inserted through the chest into the pleural space, and a sample of fluid is collected. The sample is then sent to the lab where it undergoes cytological tests to determine its histological composition and the possible presence of tumorous cells. Similarly, if there is suspicion of a peritoneal mesothelioma, it is possible to collect and analyze the ascitic fluid. Nonetheless, this test has limitations, because it cannot discriminate between cell types (epithelial, sarcomatous, or mixed) of the tumor and very often it shows false negatives. This is why, if there are no contraindications, a physician will prescribe a biopsy. Thoracoscopy is a small surgical procedure that allows for the collection of pleural tissue samples. The surgeon performs a small incision on the chest wall and inserts a thin tube with a micro-video camera at the end, which is connected to a video system. This allows the surgeon to view the tumor and to collect a sample. Laparoscopy is the abdominal equivalent to thoracoscopy, and is performed to observe a lesion caused by peritoneal mesothelioma and to collect samples. Thoracotomy and laparotomy are for sampling larger tissue samples. These surgical procedures require the opening up of the chest and abdomen, and at times it is possible to remove the entire tumorous mass.

Another procedure used is mediastinoscopy. A thin tube with a video camera is inserted at the neck and it is pushed down below the sternum toward the chest. This method allows the surgeon not only to perform a biopsy, but also to analyze the lymph nodes of the mediastinum. Although mediastinal lymph nodes are rarely involved, this test is useful in establishing if the disease is still localized or if it has already spread to other areas. When necessary, it can also be useful in discriminating a mesothelioma from lung cancer. Patients affected by pleural mesothelioma can be prescribed a bronchoscopy, a procedure where a flexible tube is inserted through the mouth and pushed down the trachea and the bronchi, allowing for the detection of masses along the airways, which may require biopsies.

Once removed, the tissue sample is viewed under the microscope. Nevertheless this step does not offer enough information to formulate a diagnosis. In fact, when viewed on a microscope, mesothelioma can show characteristics very similar to many other types of tumor. Sometimes it is very hard to distinguish between a pleural mesothelioma and lung cancer, or between a peritoneal mesothelioma and ovarian cancer.

To be able to distinguish MMe from other tumorous forms, specific laboratory tests are conducted on biopsied tissue. Many of these tests aim at recognizing specific markers expressed by MMe cells through histochemical and immunohistochemical techniques. In addition, the use of a scanning electron microscope has a complementary purpose, as it allows images to be enlarged up to 100 times more than the common microscope.