The processing of tissue from a mesothelioma biopsy
Tissue removed by biopsy is usually placed into a container with formalin or other preservative. The container is tagged with the name and other necessary details of the patient. When the pathologist receives it, he first observes it with the naked eye and makes a gross description by noting its size, weight and color. He decides which parts of the biopsy should be examined first. The tissue has to be compared with normal cells and identified. For this, the tissue is prepared for examination under a microscope.
Frozen section techniques are used when the surgeon needs a diagnosis while the patient is still in surgery under anesthesia. To do this, the removed tissue is frozen at once and cut into thin layers. It is then placed on a slide and stained with dyes to get a very clear view of the nucleus, cytoplasm and other contents of the cell. This is usually not necessary or helpful for diagnosing mesothelioma.
Permanent section usually takes a few days. The processed tissue is embedded in a paraffin block. After the block hardens, very thin slices of the tissue are cut and mounted on a slide. The tissue on each slide can be stained with different dyes for examination.
The pathologist looks at the slides under a microscope and looks for a number of things that demonstrate that the tissue is cancerous. These include structures inside each cell as well as the way the cells have grown together.
Mesothelioma is very difficult to diagnose. The pathologist will use special procedures, such as immunohistochemical stains, and DNA microarray analysis to help aid in the diagnosis. He or she will also look at the cells under an electron microscope which reveals much more of the tiny details in the cell.
There are a number of other specialized tests used to make the diagnosis of mesothelioma. If the pathologist cannot be sure, he can send the slides to an expert pathologist who has diagnosed many cases of mesothelioma.
Mesothelioma will also be classified by type, either epithelioid, sarcomatoid, or mixed.
After all the required information is obtained, the pathologist will write a report.
Dr. Kaplan