The science of pathology

Pathology is the science of diseases. It examines the aetiologies and etiopathogenesis of the diseases, and the changes and functional defects of tissues and organs caused by disease, by employing morphological, immunological and molecular techniques.

Department of Pathology is a part of surgical medicine unit that works in close collaboration with all clinical branches and plays a critical role in diagnosis and determining the treatment strategy of the diseases. It is a disciple that guides the treatment of the patients by detecting many diseases at early stages before they progress to late stage cancers and inform the clinicians accordingly.

In the pathology laboratory there should be pathologists who are expert in different fields of pathology, pathology technicians, and the necessary apparatus, equipments and a microscope. First of all, small endoscopic biopsies, incisional biopsies etc. should be transported to the pathology laboratory in an air-tight container that contains fixative. Bigger specimens such as organ resections and extremities amputations should be transported immediately to the laboratory wrapped within a clean cloth that does not contain fixative, and these bigger specimens should be opened by employing the proper dissection method and should be incubated in proper containers that enable formalin diffusion into the all tissue layers.

Transportation procedures for cytological materials vary depend on the material. Firstly the specimen is evaluated visually by the clinical pathologist at the macroscopy laboratory by noting the weight, dimensions, colour consistency and any unexpected lesions. Afterwards, depending on the material type and its pathology standardized sampling methods are used. In the hospitals that utilize advanced standards such as ours, fully automated tissue processing equipments are used and the specimens are treated with various chemicals for 14-16 hours to prepare them for the sectioning procedures.

Pathology technicians that are educated to graduate or undergraduate level then take sections of the paraffin-embedded samples by a microtome that can cut the specimens at a 1 thousandth of 1 mm thickness. The sections are then stuck on a microscope slide and are stained by a standard tissue stain called Haematoxylin-Eosin. Following this process tissue samples are ready to be studied under a microscope.

Methods used in differential diagnosis:

a) Histochemical stains: shows the material build-up in a cell, its basic building blocks or infectious agents (bacteria, fungi).

b) Immunohistochemical stains: It is an immunology-based differential diagnosis method that is based on identifying building blocks inside a cell and the chemical reactions by enzymes that are tagged by special colours. It is used in identifying the tumor type, the tissue the tumor originates from, the normal or extraordinary products produced by it, and therefore it is employed for determining the tumor type and whether tumor specific drugs could be used in the treatment.

c) Immunofluorescent microscopy: It is used in diagnosis of some skin, kidney and vascular disease etiologies of which are from immune-based mechanisms. It relies on the principle of identifying the deposited immunecomplexes by fluorescently labelled stains and evaluating the fluorescence by special light filters in dark field.

d) Electron microscopy: some cell-based build-ups and organelle changes that could not be detected by the abovementioned conventional methods are identified by this method. And especially, the need for this method is high in evaluation of medical kidney biopsies (for showing to which extend the immunecomplexes are deposited in the glomerulus or some extracellular deposits such as amyloid fibrils).

In cases when no definite result can be reached by light microscopy (е), the abovementioned differential diagnostic techniques are used by starting from the cheapest and the most practical one and working our way up step by step. In reporting the results, the goal is to provide the clinician the most detailed information in the most accurate way regarding the disease.

Scientific autopsy. The goal is to observe and identify the morphological changes and symptoms that the disease caused in the organs, to sometimes identify the definite cause of death and to provide information to the clinician on the disease at hand. For this purpose, all three cavities in the human body (skull, chest and abdominal cavities) are opened up and after making the necessary evaluations closed up appropriately.

Дата добавления: 2015-11-16