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A pathologist is a specialist who diagnoses diseases by examining biopsy samples, and the tissues and cells in them, under a microscope. Pathology is a specialty that focuses on giving the definitive diagnosis of many diseases, above all cancer. The services provided by the pathologist are generally delivered through the referring clinician. The pathologist, whom many patients never meet, has a role as something like a doctor's doctor.

The pathologist examines tissues and cells under a microscope to understand what kinds of abnormalities are present in the tissue sample. As a result of this examination, the pathologist writes a report explaining the diagnosis. The information in the report helps the clinician plan the patient's treatment.

A pathologist is a medical doctor.

Legally, every pathologist can examine every biopsy. However, given the rapidly increasing volume of knowledge, it is difficult for one pathologist to master all the details of pathology. For this reason, large hospitals have physicians who concentrate on various branches of pathology and have greater accumulated knowledge and experience. In our hospital as well, there are pathologists specialized in gastropathology, gynecopathology, nephropathology, uropathology, hematopathology, cytopathology, bone and soft tissue pathology, breast pathology, endocrine pathology, neuropathology, ear, nose and throat pathology, dermatopathology, lung pathology and oral pathology, and the samples that come to our department are evaluated by the pathologist specialized in the region the sample belongs to.

It is defined as the removal of tissue and cells so that they can be examined under a microscope. When a tissue or fluid sample is taken with a thin needle, the procedure is called a needle biopsy or fine needle aspiration. A biopsy sample is usually small, but it must also be large enough to adequately represent the existing abnormality; otherwise a reliable result may not be obtained from examining the biopsy. Sometimes the whole abnormality needs to be removed, which is often done for treatment as well as for diagnosis; in this case a much larger piece, or even an entire organ, may be sent to pathology. This type of biopsy is called an excisional biopsy.

The biopsy sample is placed in a container filled with 10% formalin solution and delivered to the pathology department; this fluid prevents the tissues from deteriorating, otherwise the samples become unsuitable for pathological examination. Biopsy samples can be stored this way at room temperature for a long time. However, although tissue stored in formalin does not deteriorate, when this period is prolonged (preferably not longer than 72 hours) the formalin may adversely affect some additional tests that may be needed later, so it is ideal for the sample to reach the pathology department as soon as possible. Afterward, in the pathology department, samples are stored at room temperature as blocks embedded in paraffin. Thin sections obtained from these blocks and placed on glass slides are stained with special dyes and become the slides that are examined under the microscope. These slides are also stored at room temperature.

By law, paraffin blocks must be stored for 10 years, slides for 20 years, and reports indefinitely. In our hospital, blocks and slides are never discarded; the reports, blocks and slides are all stored indefinitely.

No.

Yes, they do. This can happen when the patient requests it and wants to talk with their pathologist, or when the pathologist needs to obtain information about the patient and wants to talk with the patient.

Tissue samples are labeled as soon as the biopsy is taken and delivered to the pathology department labeled (so that it is clear which patient they belong to). In the pathology department, each sample is given a biopsy number and this number is written on the biopsy report.

Cancer is a condition in which abnormal cells multiply in an uncontrolled and disorderly way. There are many types of cancer belonging to every organ and tissue.

Benign is derived from a Latin word meaning mild or kindly. In theory, all benign tumors behave well and do not pose a serious danger to the patient. Benign tumors can usually be separated easily from normal tissues and can therefore be removed surgically. However, as in brain tumors, depending on the area in which they are located, even benign tumors can sometimes create problematic situations for the patient or cause death.

Malignant is derived from a Latin word meaning malevolent and is used as the opposite of benign. Malignant tumors generally do not remain within the boundaries of the tissues they originate from and invade the surrounding tissue (infiltration, invasion). In addition, malignant cells can break away from the original mass and enter the blood or lymphatic circulation, and thus can spread to other parts of the body far from the organ they originated in (distant metastasis).

Yes, in many cases cancer is easy to recognize microscopically. However, there may be situations in which a more comprehensive examination and special tests such as immunohistochemistry and molecular analyses are required for a definitive diagnosis.

In some cases, blood tests may give data that are strongly suspicious for cancer, and may almost be called diagnostic (such as PSA in prostate cancer, or the AFP level in hepatocellular cancer or some testicular cancers). However, a definitive diagnosis of cancer is only possible through pathological examination.

Evaluation of difficult-to-diagnose cases by more than one pathologist is a common situation in our department. Pathologists share problematic cases with one another. In addition, meetings called "tumor boards," in which pathologists, oncologists and surgeons come together and discuss patients with all their details, are held, and at these meetings the pathological findings are shared with all the doctors involved with the patient. A decision about the patient's diagnosis and treatment is reached at these meetings.

A pathology report is a report that states that a biopsy sample belongs to a particular patient and contains the details of the diagnosis.

The pathology report includes the following information:
• Patient information: Name and surname, age
• Name of the patient's doctor
• Date of the biopsy
• Type of tissue sampled and method of sampling
• Preliminary clinical diagnosis
• Macroscopic description: Describes the size, weight and color of the tissue and the changes visible in the tissue to the naked eye
• Microscopic description: Describes the changes observed in the tissue under the microscope
• Diagnosis: Describes the diagnosis obtained after macroscopic and microscopic examination
• Name of the pathologist and the laboratory

If a diagnosis of "cancer/neoplasia" is made after the pathological examination, the pathology report includes the following additional information.

- Tumor type and grade (characteristics that give information about how abnormal the cells look under the microscope and how quickly the tumor may grow and spread)
- Size of the tumor
- Surgical margins of the tumor
1. Positive surgical margin: the tumor continues at the surgical cut edge of the piece removed from the patient
2. Negative and intact surgical margin: there is no tumor at the surgical cut edges of the piece removed from the patient
3. Close to the surgical margin: there is no tumor at the surgical cut edges of the piece removed from the patient, but the tumor is very close to these cut edges
- Notes on the results of the additional tests used to reach the diagnosis

After a biopsy sample has been identified as cancerous, the pathologist may request additional tests in order to identify certain features that cannot be determined with the routine stain, hematoxylin and eosin (H&E). The most commonly used of these are immunohistochemical stains. Immunohistochemistry is a method in which antibodies are used to recognize certain specific antigens in cells. Immunohistochemical tests are often used

• to understand which cell the cancer/neoplasia originated from
• to distinguish between different types of cancer
• to classify cancers into their subtypes.

Another type of additional test is molecular diagnostic tests. These tests are used to detect specific, diagnostic genetic abnormalities that have been identified in cancer cells, and the results are added to the pathology report.

Tests are available to detect certain DNA abnormalities that have been identified in association with particular cancer types. Pathologists can use these tests for diagnostic purposes when necessary.

• • Fluorescence in situ hybridization (FISH): Identifies the position of certain genes. It is used to detect genetic abnormalities such as chromosomal abnormalities and translocations (the movement of a gene from one place to another), deletions (the absence of a gene) or amplifications (an increase in the number of copies of a gene).

• • Polymerase chain reaction (PCR): Based on creating many copies of specific DNA sequences with diagnostic significance and detecting them.

• • Real-time or quantitative PCR: Allows measurement of the amount of a specific DNA sequence with diagnostic significance.

• • Reverse-transcriptase polymerase chain reaction (RT-PCR): Based on creating many copies of a specific RNA sequence with diagnostic significance and detecting them.

Yes, most molecular studies can be performed on a paraffin block.

It is not suitable to perform molecular studies on tissues that undergo a process called decalcification so that sections can be cut in pathology, such as bone marrow and bone tissue, because the nucleic acids that make up DNA and RNA are broken down during this process.

Because tissue samples containing bone are very hard, they must first be softened by a process called decalcification before the sections needed for microscopic examination can be cut from them. For this reason, the pathological examination of large samples of bone tissue takes longer than that of other samples.

Yes, you can. Cases from our department's archive are given to the patient together with a copy of the pathology report. In such cases, it is preferred to make new sections from the paraffin blocks and give these to the patient, and no identification is requested in this situation. However, when this is not possible or when the original blocks and slides are requested, the blocks and slides are handed over to the patient in exchange for identification, on condition that they are returned. The reason for this is that we are obliged to keep the blocks and slides for a certain period and that these materials constitute evidence for the findings in the pathology report.

Yes, in some cases a biopsy sample taken from the patient during surgery is examined by the pathologist using special methods, and an urgent diagnosis is made. This is known as a "frozen section" or "intraoperative consultation." The surgeon waits for the pathologist's diagnosis during the operation and directs the surgery according to this diagnosis. In such cases, the pathologist, whom the patient never meets, can play a life-saving role.

Yes. Today, within the scope of targeted therapy, in order for some drugs available especially for cancer treatment to be given to the patient, the biopsy tests of these patients must include the results of certain additional tests indicating which drug they will benefit from. Since the additional tests required for these drugs must be performed on tissue, such studies are generally reported within the main pathology report (as with the C-erb-B2 level in breast cancer) or as a separate report by the pathologist.

A brain tumor, like tumors of other organs, is a mass formed in the brain by cells that grow uncontrollably. However, because the brain is the center of many critical functions, tumors arising in this organ have serious consequences. As with all tumors, the single most accurate way to diagnose a brain tumor is a biopsy. The surgeon performs the biopsy, and the pathologist makes the definitive diagnosis and states whether the tumor is benign or malignant.