How Was This Diagnosis Determined, and How Accurate Were the Tests?

Although you probably took many different tests leading up to your diagnosis, a tissue biopsy is normally the final determining factor. Following are some tests your doctor may recommend, and what may or may not be concluded from these tests.

• X-rays, CT scans, and MRIs - See the imaging section for more on these techniques. On conventional x-ray film, mesothelioma appears as a markedly thickened, nodular, irregular pleural-based mass which covers the pleural surface. The tumor often encompasses the involved lung, but is only rarely seen bilaterally. Chest wall, diaphragmatic, and mediastinal invasion may be seen in advanced cases. Moderate to large pleural effusion is often noted on the affected side. On CT scan, pleural thickening greater than 1 cm can be identified in over 90% of cases; thickening which extends into the interlobular fissure is seen in 85% of cases. Absence of pleural thickening does not preclude mesothelioma, and at times, the only CT finding is that of pleural effusion.
• Cytology - Testing of the pleural fluid for malignant cells is considered to have limited value in diagnosing mesothelioma. Negative or inconclusive readings account for nearly 85% of all fluid tested. Even with a positive fluid report, many doctors prefer to perform a confirming tissue biopsy as long as it does not compromise the patient's health.
• Needle Biopsy - In this test, done under local anesthetic, a large hollow needle is inserted through the skin and into the chest cavity. The needle is then rotated, and as it is taken out, tissue samples are collected. Because of the small sample size of the tissue, this type of biopsy is considered to be only 25-60% accurate in diagnosing mesothelioma. Because tumor seeding may occur along the needle tract in approximately 20% of patients, local radiation therapy may be used in conjunction with this test.
• Open biopsy - This type of biopsy is considered to be the most accurate for mesothelioma diagnosis, and is the procedure of choice because it affords the pathologist a larger tissue sample.. It is done in a hospital under general anesthetic. As with a needle biopsy, local radiation may be used because of the possibility of tumor seeding.