Histopathology
The main branch of diagnostic medicine is histopathology which deals with tissue lesions of diseases and their formation. It also deals with tissues removed during a medical procedure to identify the exact kind of the disease (whether it is a tumor or not, benign or malignant) or the efficiency of the surgical treatment (the examination of resection margins) or it examines the previously performed treatments’ effectiveness (like prostate biopsy after radiotherapy). Every piece of tissue removed during a medical process is examined by a pathologist. So the major part of the daily routine activities involves the histopathological reading of the surgical dissections or biopsies, both endoscopic and manual. This routine histopathological diagnostics involves several supplementary examination methods, primarily special staining techniques and immunhistochemistry examinations. These serve as essential complements to pathological applications that provide the opportunity to customize treatments, to answer differential diagnostic questions, diagnose pathogens, standardize tumors, and predict tumors.
In the case of cancer patients, pathologists have a crucial role as they do not only evaluate the histopathological samples themselves but previous examinations and the patients’ own anamnesis are also taken into consideration which provides a basis of the targeted therapy.
Based on the examinations, they identify the stage of the tumor, they decide whether it is an operable lesion, and in consideration of the patient’s general condition, sensitivity to medications, they trace the prospects of the patient, and suggest a suitable therapy. Practically, it is impossible to start an oncological treatment without a pathologist’s opinion.
Intraoperative cryogenic examinations
Nowadays the intraoperative cryogenic histopathological examinations (performed during surgery) are indispensable for the appropriate surgical treatment of certain lesions. The surgeon finishes the operation only after the diagnosis based on the examined tissue sample or continues the operation if necessary. This is probably the most difficult aspect of our daily routine tasks as there is no time for doing additional examinations, it must be decided immediately whether the lesion is benign or malignant.
Hematopathology
Today, a special branch of pathology, hematopathology deals with hemopoietic and immune system diseases, tissue and cellular lesions. It is not only necessary for the identification of typical deviations but also for sampling and decisions on the applied methods. Because of the latter, modern hematopathological diagnostics can only be performed in competent centres. Hemopoiteic disorder, myeolid malignant tumors, leukemia can be diagnosed only after the combined examinations of the bone marrow and the blood. Beyond the microscopic examinations of peripheral blood and bone marrow microscopic preparation, marrow aspirate or biopsy (Yamshidi biopsy), flow cytometry, cytochemical methods (myeloperoxidase, NASD, Berlin blue, reticulum staining), immunohistochemistry, genetic and certain molecular examinations (proving of translocations by FISH method, examining clonality with PCR) are also of great importance.
The lymphatic system (lymph node, spleen, thymus, tonsils and other mucosa associated lymphoid tissue, skin) is very extensive, inflammatory or tumorous mutations can evolve in any parts of the body, in every organ.
After surgical excision on the basis of the morphological, immunohemotypical and genetic background, several forms of malignant lymphomas can be differentiated. The treatment of these is also very diverse, in certain cases immunotherapy or even stem cell transplantation may be considered which promises full recovery. Therefore, the histopathological identification of particular categories is of high importance. Immunhistochemical panels serve such a purpose and these may involve more than 10 immunostainings until the final diagnosis. Imprints are made from the unfixed lymph tissues sent for cytological and genetic examinations and in every suitable case, archiving and cryopreservation are performed for molecular processing.
Cytology
The aim of cytology examinations is to identify different lesions (normal, reactive, dysplastic, neoplastic), the tissue origins of the tumorous lesions, the degree of malignity, the examination of the diffusion, prognosis of the process and the examination of the therapy’s effect. The morphological microscopic examination of cells collected from the tissues, organs during cyto-diagnostics takes place with traditional or, if necessary, immuncytochemical staining. The advantage of this examination method is that it is fast, has little substance and instrument needs and no surgical intervention is needed for it. For the examination of certain tissues, such as different liquids, it is more suitable than histology. Its disadvantage is that it is often not representative, the most common reason being that the cells can get damaged during preparation. This method does not give the physician information about the structure of the tissue but the type of the lesion can definitely be decided before the operation.
Aspiration cytology
This is the only type of examination in the Institute where the patient and the attending physician get in personal contact. FNAC (Fine Needle Aspiration Cytology) is one of the most modern and most dynamically developing branch of cytological examinations which is an essential part of modern tumor diagnostics and an important examination method in patient follow-up. The name itself refers to the technique used in the procedure whereby the biopsy of the lesion is performed with the help of a fine needle, cells are aspirated with vacuum. Aspiration cytology is a purely diagnostic intervention.
Molecular tumor pathology
In certain tumorous lesions histological diagnostics are indispensable but not sufficient for identifying the disease precisely, today in most cases it can only be done through the clarification of the genetic background.
Genetic and gene regulation disorders in certain tumors and even in particular patients, can result in very different behaviors and growth features. It is possible that a tumor with the same histological type responds differently to the treatment scheme.
The main objective of the molecular examinations is to detect the influence of the gene mutations on the effective therapy of the relevant pharmacological treatment. This way an effective therapy can be chosen on the basis of the molecular features and sensitivity of the tumor. The choice of the most appropriate treatment is the result of professional cooperation (oncology team) which is determined by the pathological evidence and the molecular pathological results. The most frequently required examinations are: KRAS, NAS, EGFR, BRAF, examination of gene mutation and HPV virus detection.
Fluorescence in situ hybridization (FISH)
Chromosomal deviations can be identified on a morphological basis with the FISH examination method, for example, in stomach and breast cancers the oncogene amplification of HER2 (Human Epidermal Growth Factor Receptor 2) can be determined from histological sections.
In several cases diagnosis is made with the identification of specific translocations, such as in certain lymphomas, Ewing- sarcoma or more recently in Xp11 translocational renal cancer.
Autopsy
Pathological examinations represent an extremely important part of medicine. These do not only ascertain the pathological conditions leading to a person’s death but also investigate the diseases, causes of death within the general population, control the effectiveness of the applied diagnostic and medical methods in health care providing important feedback to the physician. Act CLIV of 1997 on Healthcare includes the regulations concerning autopsy and other tasks related to the dead.