Let's start with brain tumors. Dr. Anton Titov, MD. Sometimes brain tumors are diagnosed clinically. Neurosurgeons usually remove the tumor. Then the material from the tumor gets into your hands. Brain tumor biopsy gets to the pathologist. Could you please walk us through this. How do you diagnose brain tumors? Dr. Anton Titov, MD. How do you establish brain tumor molecular diagnosis? Dr. Sebastian Brandner, MD. Neurosurgeon sends us tumor material. Everything else they expect us to solve for them. We help not only them. We also help the oncologists, the neurologists, and the patient. After we receive the tumor sample material, it is being fixed in a fixative. This tumor material is processed. It becomes something that we can cut into very thin slices. So that results in the slides like this. It's a small glass slide. Dr. Sebastian Brandner, MD. You can see here. Then the specimens are "mounted" in the center of the slide. It goes to another procedure. We dye the cells with a dye. So the nuclei, the cytoplasm, the neuron processes look distinctive under the microscope. After that, the actual diagnostic procedure starts. So we look through the microscope first. We identify what type of brain tumor it is. Dr. Anton Titov, MD. Is it intrinsic brain humor? Or is it extrinsic brain tumor? Such as meningioma or metastasis. Or is it something entirely different? Is it inflammation? Sometimes we get material from the spine. It is actually not a brain tumor as such. We then have to send tumor to other specialists. Because it's often soft tissue tumors. Now, back to the brain tumors. Under the microscope we make the first decision. The first decision is this. What type of brain tumor is it? Dr. Sebastian Brandner, MD. That clearly defines and determines what we do next. We then order a number of stains that tell us a little bit more about the nature of the tumor. So we already know it. Is this glioma? But we want to know a little bit more details. Dr. Anton Titov, MD. What type of glioma is it? What subtype? So we order the second round of special stains. Today it is all done on a machine. These special stains are called immunohistochemistry or immunohistochemical staining. A day later they arrive again on our microscope desk. We discuss them. We will look at them. That gives us a fairly clear idea what we are dealing with. I would say, it is the very first step. We are just looking at the stained slide. That we do with all the brain tumor biopsies. In our hands, 60 - 70% of those brain biopsies require the second step. It is the immunostaining. it’s important for intrinsic brain tumors. They are gliomas and many other types of tumors. After that we have a very good idea about nearly all brain tumors. But probably 10% of tumors require additional diagnostic tests. Especially gliomas. Dr. Sebastian Brandner, MD. So we look further. Because you want to find the precise diagnosis. We want to really go into detail. So that is the last step. It's called "molecular diagnostics". So this is done entirely differently. That leaves the domain of pathology. It goes into molecular biology. Tissues of the tumor are taken off from the blocks, off the slides. Then brain tumor tissue is prepared. We can extract the nucleic acids, the DNA. This material is then subjected to molecular pathology tests, We usually do a quantitative PCR. And in rare cases we also do a DNA microarray type of investigations. So this last step. Dr. Sebastian Brandner, MD. It is probably done in 1% of the tumors. Sometimes all the other tests are not giving us sufficient clarity of the brain tumor diagnosis. We need sufficient details of information. All that brain tumor diagnostic information is then put into a report. This report is typed up on a computer. The computer is connected to database. Dr. Anton Titov, MD. The database is then feeding back that information to the clinical teams. We authorize the report electronically to be released. It goes straight away to the hospital's clinicians. Dr. Sebastian Brandner, MD. They can review brain tumor diagnosis report. But that's not the end of the diagnostic process. Precise brain tumor diagnosis starts with microscopic examination of stained brain tumor tissue. Is it a metastatic or primary brain tumor? Is it meningioma or glioma? Brain tumor diagnosis expert explains.