Introduction to Pathology PDF

Introduction to Pathology Diseases An abnormal variation in structure or function of any part of the body Pathology ‘Patho’ means disease and ‘logy’ means study therefore pathology is a scientific study of disease that Pathology gives explanations of a disease by studying...

Introduction to Pathology Diseases An abnormal variation in structure or function of any part of the body Pathology ‘Patho’ means disease and ‘logy’ means study therefore pathology is a scientific study of disease that Pathology gives explanations of a disease by studying the following four aspects of the disease 1. Etiology 2. Pathogenesis 3. Morphologic changes 4. Functional derangements and clinical significance 1. Etiology Etiology of a disease means the cause of the disease If the cause of a disease is known it is called primary etiology If the cause of the disease is unknown it is called idiopathic/ cryptogenic There are two major classes of etiologic factors: Congenital: is a condition existing at birth or before birth Acquired (infectious, inflammatory, chemical, physical, etc) 2. Pathogenesis Pathogenesis means the mechanism through which the cause produces the clinical signs and symptoms 3. Morphologic changes The morphologic changes means the structural changes in cells or tissues due to disease The structural changes in the organ can be seen with the naked eye or they may only be seen under the microscope  Gross/ Macroscopic findings: are the structural changes in the organ that can be seen with the naked eye Microscopic/histologic findings: are the structural changes in the organ that can only be seen under the microscope Commonly diseases have certain specific gross or microscopic changes, and this helps in the diagnosis of that disease 4. Functional alterations and clinical significance When an organ is damaged by a disease, the normal function of that organ is affected and this will lead to the development of certain clinical changes called signs & symptoms  Symptoms: is something experienced and reported by the patient e.g. ‘I have a headache’, ‘I have a pain in my stomach’ etc. Basically it is what the patient will tell the doctor. Signs: are findings discovered by the physician during examination of the patient e.g. doctor finds a liver or spleen enlargement while examining the abdomen etc. The combination of signs and symptoms is called clinical features. In summary, pathology studies:- Etiology  Pathogenesis  Morphologic changes  Clinical features & Prognosis of all diseases  Understanding pathology helps in understanding how the clinical features of different diseases occur & how their treatments work In addition, the pathologist can use the morphologic changes seen in diseases to diagnose different diseases Diagnostic techniques used in pathology a. Histopathology b. Cytopathology c. Hematopathology d. Immunohistochemistry e. Microbiological examination f. Biochemical examination g. Cytogenetics h. Molecular techniques i. Autopsy  A. Histopathological techniques Histopathological examination studies tissues under the microscope Tissues are obtained by doing biopsies and excision of organs by physicians & surgeons  Tissue is processed in a special multistep way and the end result is very thin slices of stained tissue glued on a slide During this study, the pathologist looks for abnormal structures in the tissue  B. Cytopathologic techniques Cytopathology is the study of cells from various body sites to determine the cause of disease  C. Hematological examination To study disease of blood cells  D. Immunohistochemistry A staining technique that uses antibodies to check for certain antigens in cells or tissue  E. Microbiological tests This is a method by which body fluids or tissue are examined to identify microrganisms responsible for many diseases  F. Biochemical tests which measure the disturbances in substances (protein, sugar, oxygen, etc.) in blood and urine to diagnose diseases  G. Clinical genetics (cytogenetics) Is the study of chromosomal abnormalities  H. Molecular techniques Molecular techniques are used to detect genetic diseases  I. Autopsy (Forensic Pathology) Autopsy is examination of the dead body to identify the cause of death Branches of Pathology Histopathology Cytopathology Haematology Forensic pathology Chemical pathology