General Pathology Lecture Notes PDF

GENERAL PATHOLOGY | Jeff Jason N. Octaviano, RMT, MD LESSON 1: Int roduct ion t o Pat hology Learning Objectives: Define pathology Discuss the core aspects of disease in pathology Know the diagnostic techniques used in pathology Know the various categories of the causes of diseases Know the c...

GENERAL PATHOLOGY | Jeff Jason N. Octaviano, RMT, MD LESSON 1: Int roduct ion t o Pat hology Learning Objectives: Define pathology Discuss the core aspects of disease in pathology Know the diagnostic techniques used in pathology Know the various categories of the causes of diseases Know the course, outcome, consequences of diseases PATHOLOGY DEFINITION Pathos = Suffering Logos = Study Study of suffering Scientific study of changes in the structure and function of the body in disease Provides the scientific foundation for the practice of medicine “The foundation of modern pathology is understanding the cellular and molecular aberrations that give rise to diseases.” PATHOLOGY SUBDIVISIONS General - dealing with general principles of disease ○ Morphological ○ Non -morphological Systematic - includes study of diseases pertaining to the specific organs and body systems. PATHOLOGY CORE ASPECTS OF THE DISEASE 1. Etiology ○ Origin of the disease ○ Primary etiology - cause of a disease is known ○ Idiopathic - cause of the disease is unknown ○ Why a disease arises? 2. Pathogenesis ○ Steps in the development of disease ○ How a disease develops PATHOLOGY CORE ASPECTS OF THE DISEASE 3. Morphologic changes ○ Structural alterations in cells or tissues that occurs following the pathogenetic mechanism ○ Gross - changes that can be seen with the naked eye ○ Microscopic - changes seen under the microscope 4. Functional derangements and clinical significance ○ Clinical features (signs and symptoms) ○ Prognosis of the disease PATHOLOGY CORE ASPECTS OF THE DISEASE PATHOLOGY DIAGNOSTIC TECHNIQUES Histopathology Cytopathology Hematopathology Immunohistochemistry Microbiological examination Biochemical examination Cytogenetics Molecular techniques Autopsy A. HISTOPATHOLOGY Histopathological techniques ○ Histopathological examination studies tissues under the microscope obtained by biopsy ○ Biopsy - a tissue sample from a living person to identify the disease Incisional (portion, diagnosis) Excisional (entire, diagnosis and removal) ○ Macroscopic and Microscopic Examination ○ Gold standard for pathologic diagnosis A. HISTOPATHOLOGY 1. Fixation - putting the removed tissue into adequate amount of 10% Formaldehyde (10% formalin) To p re ve n t a u to lysis a n d b a cte ria l d e co m p osition a n d p u tre fa ctio n To coa gu la te th e tissu e to p re ve n t lo ss of e a sily d iffu sib le su b sta n ce s To fortify th e tissu e a ga in st th e d e le te riou s e ffe cts of th e va rio u s sta ge s in th e p re p a ra tio n o f se ction s a n d tissu e p ro ce ssin g To le a ve th e tissu e s in a co n d itio n wh ich fa cilita te s d iffe re n tia l sta in in g with d ye s a n d o th e r re a ge n ts STEPS IN PROCESSING TISSUES 1. Fixation - Preserves tissue structure and prevents decomposition. 2. Dehydration - Removes water from tissue using alcohol 3. Clearing - Replaces alcohol with a solvent miscible with both alcohol and wax 4. Infiltrating - Tissue is saturated with molten wax for embedding. 5. Embedding - Tissue is oriented and surrounded by wax within a mold. 6. Trimming/Sectioning - Tissue block is cut into thin slices using a microtome. 7. Staining - Color is added to tissue sections to highlight structures. 8. Mounting - Sections are placed on a slide and covered with a coverslip. 9. Labelling - assigning unique identifiers B. CYTOPATHOLOGIC TECHNIQUES Cytopathology ○ Study of cells shed off from various body sites (lesions) to determine the cause or nature of disease ○ Application: Screening for the early detection of asymptomatic cancer Diagnosis of symptomatic cancer Surveillance of patients treated for cancer ○ Advantages: Cheap Takes less time Needs no anesthesia to take specimens B. CYTOPATHOLOGIC TECHNIQUES Cytopathology ○ Methods Fine-needle aspiration cytology (FNAC/FNAB) Cells are obtained by aspirating the diseased organ using a very thin needle under negative pressure. For deep organs, it is guided by fluoroscopy, Utz, CT Cheap, fast, accurate Exfoliative Cytology Examination of cells that are shed spontaneously into body fluids or secretions Abrasive Cytology Methods by which cells are dislodged by various tools from body surfaces Pap smears B. CYTOPATHOLOGIC TECHNIQUES C. HEMATOPATHOLOGY Hematological Examination ○ Method by which abnormalities of the cells of the blood and their precursors in the bone marrow are investigated ○ To diagnose the different kinds of anemia & leukemia D. IMMUNOHISTOCHEMISTRY Immunohistochemistry ○ Method is used to detect a specific antigen in the tissue in order to identify the type of disease. E. MICROBIOLOGICAL EXAMINATION Microbiological Examination ○ Method by which body fluids, excised tissue, etc. ○ Examined by microscopical, cultural and serological techniques to identify microorganisms responsible for many diseases. F. BIOCHEMICAL EXAMINATION Biochemical Examination ○ Method by which the metabolic disturbances of disease are investigated by assay of various normal and abnormal compounds in the blood, urine, etc. G. CYTOGENETICS Clinical Genetics ○ Method in which inherited chromosomal abnormalities in the germ cells or acquired chromosomal abnormalities in somatic cells are investigated using the techniques of molecular biology. H. MOLECULAR PATHOLOGY Molecular Pathology ○ Detection and diagnosis of abnormalities at the level of DNA of the cell ○ Molecular techniques Fluorescent in situ hybridization (FISH) Southern blot Polymerase Chain Reaction (PCR) I. AUTOPSY Autopsy ○ Examination of the dead body to identify the cause of death. ○ This can be for forensic or clinical purposes. CAUSES OF DISEASE Environmental Ge n e tic CAUSES OF DISEASE 1. Environmental Physical agents - trauma, radiation, extreme temp, electric power Chemicals - drugs Nutritional deficiencies and excesses - poor supply, interference with absorption, inefficient transport within the body, defective utilization, dietary excess Infection & Infestations - viruses, bacteria, fungi, protozoa, metazoa via cell destruction Immunological factors - hypersensitivity, immunodeficiency, autoimmunity Psychogenic Factors - mental stresses 2. Genetic Factors Hereditary factors that are inherited genetically from parents. COURSE OF DISEASE Different stages in the natural history of disease: ○ Exposure to various risk factors (causative agent) ○ Latency - period between exposure and biological onset of disease ○ Biological onset of disease - marks the initiation of disease, however, without any sign or symptom ○ Incubation (induction) - refers to variable period of time without any obvious signs or symptoms from the time of exposure ○ Clinical onset of the disease - when signs and symptoms of the disease become apparent ○ The onset of permanent damage ○ Death COURSE OF DISEASE Different stages in the natural history of disease: OUTCOME AND CONSEQUENCES OF DISEASE Following clinical onset, disease may follow any of the following trends: ○ Resolution can occur leaving no sequelae ○ The disease can settle down, but sequelae are left, or ○ It may result in death CLINICAL AND BIOLOGIC DEATH Clinical Death ○ The reversible transmission between life and biologic death ○ Period of respiratory, circulatory, and brain arrest during which initiation of resuscitation can lead to recovery ○ Begins with either the last agonal inhalation or the last cardiac contraction ○ Signs: The patient is without pulse or blood pressure and is completely unresponsive to the most painful stimulus. The pupils are widely dilated Some reflex reactions to external stimulation are preserved Recovery can occur with resuscitation. CLINICAL AND BIOLOGIC DEATH Biological Death ○ Sure sign of death, which sets in after clinical death ○ An irreversible state of cellular destruction. ○ It manifests with irreversible cessation of circulatory and respiratory functions ○ irreversible cessation of all functions of the entire brain, including brain stem. EXERCISES/ SUMMARY 1. What is pathology? What core aspects of disease does it study? 2. Why should you study pathology? 3. What is pathogenesis? 4. What are the diagnostic modalities used by the pathologist? 5. What are the purposes of tissue fixation? 6. Describe the course of disease. References: GENERAL PATHOLOGY LECTURE NOTES For Health Scie n ce Stu d e n ts Rob b in s & Co tra n Ba sics Pa th o lo gy, 11th Ed ition Thank you for list ening! CREDITS:This presentation template was created by Slidesgo , and includes icons by Flaticon and infographics & images by Freepik Please read in advance: Chapt er 1: Cell Injury, Cell Death, and Adaptations *Pre-test :) CREDITS:This presentation template was created by Slidesgo , and includes icons by Flaticon and infographics & images by Freepik