Introduction to Pathology And its rule in the diagnostic process Dr: Wael H.Mansy, MD Assistant Professor College of Pharmacy King Saud University

It is the “ It is the “ Scientific study of disease". "scientific study of the molecular, cellular, tissue, or organ system response to injurious agents." Definition of pathology Pathology serves as a "bridge" or "link" between the preclinical sciences (anatomy, physiology, ……etc.) and the courses in clinical medicine.

What is the Disease? It is the “ It is the “State in which an individual exhibits an anatomical, physiological, or biochemical deviation from the normal” Disease may be defined as :Disease may be defined as : an abnormal alteration of structure or function in any part of the body.

Classification of the disease  according to body organ  according to etiology

Etiological classification of the disease NameEtiology Inherited or familial disease Caused by defects inherent in the chromosome or gene of one or both parents that is transmitted to the offspring e.g. Down’s syndrome. Congenital diseasePresent at birth; some are inherited while others may be caused by a developmental defect of known or unknown origin. e.g. Cleft lip. Toxic diseaseCaused by ingestion of a poison e.g. inhalation of carbon monoxide Infectious diseaseResulting from an invasion of living pathogenic organism e.g Influenza Traumatic diseaseCaused by physical injury e.g. accidents. Degenerative diseaseThe primary abnormality is degeneration of various parts of the body. E.g. osteoarthritis.

Etiological classification of the disease NameEtiology Immunologic disease Hypersensitivity, autoimmunity, immunodeficiency are three types of immune reactions with harmful effects to the host. E.g. AIDS Neoplastic diseaseAbnormal cell growth that leads to various types of benign and malignant tumors. E.g. fetal alcohol syndrome. e.g. breast cancer. Nutritional diseaseDeficiency of protein, calories, or vitamins e.g. malnutrition. Metabolic diseaseResulting from a disturbance in some important metabolic process of the body. e.g. DM.

Etiological classification of the disease NameEtiology Psychogenic diseaseOriginating in mind, having emotional or psychogenic origin in relation to symptom. E.g. depression. Iatrogenic diseaseA disease or disorder produced inadvertently as a result of treatment by a health care professional for some other disorder. E.g. fetal alcohol syndrome. Idiopathic diseaseDisease of unknown cause. E.g. HTN.

In order for a subject or course to be meaningful, one should become familiar with the basic terminology applicable to that subject. Basic Language of Pathology

Branches of Pathology General Pathology General Pathology Systemic Pathology Systemic Pathology Gross Pathology Gross Pathology Cellular Pathology Cellular Pathology Surgical Pathology Surgical Pathology Clinical Pathology Clinical Pathology Immunopathology Immunopathology

General Pathology General Pathology Common changes in all tissues. e.g.. Inflammation, cancer, ageing, edema, hemorrhage ….etc. Common changes in all tissues. e.g.. Inflammation, cancer, ageing, edema, hemorrhage ….etc. Systemic Pathology Systemic Pathology Discussing the pathologic mechanisms in relation to various organ systems e.g. CVS, CNS, GIT…..etc. Discussing the pathologic mechanisms in relation to various organ systems e.g. CVS, CNS, GIT…..etc. Learning Pathology:

Definition. Epidemiology – Where & When. Etiology – What is the cause? Pathogenesis - Evolution of dis. Morphology - Structural Changes Functional consequences Management Prognosis Prevention Pathology What should we Know About A Disease

Pathology focuses on 4 aspects of disease: ETIOLOGY: Cause of disease. ETIOLOGY: Cause of disease. PATHOGENESIS: PATHOGENESIS: Mechanisms of development of disease. Mechanisms of development of disease. MORPHOLOGY: MORPHOLOGY: The structural alterations induced in cell and tissues. FUNCTIONAL CONSEQUENCES: FUNCTIONAL CONSEQUENCES: Functional results of the morphologic changes, as observed clinically. Functional results of the morphologic changes, as observed clinically.

Knowledge of etiology remains the backbone of: Disease diagnosis Disease diagnosis Understanding the nature of diseases Understanding the nature of diseases Treatment of diseases. Treatment of diseases. Etiology “Study of the cause of a disease"

An etiologic agent : An etiologic agent : is the factor (bacterium, virus, etc.) responsible for lesions or a disease state. Predisposing Causes of Disease: Predisposing Causes of Disease: Factors which make an individual more susceptible to a disease (damp weather, poor ventilation, etc.) Exciting Causes of Disease: Exciting Causes of Disease: Factors which are directly responsible for a disease (hypoxia, chemical agents…. etc.). Factors which are directly responsible for a disease (hypoxia, chemical agents…. etc.).

One etiologic agent several diseases, as smoking.One etiologic agent several diseases, as smoking. Disease Several etiologic agents one disease, as diabetes. Several etiologic agents one disease, as diabetes. Disease One etiologic agent - one disease, as Malaria. One etiologic agent - one disease, as Malaria. Etiology

 Environmental agents: Physical Physical Chemical Chemical Nutritional Nutritional Infections Infections Immunological Immunological Psychological Psychological  Genetic Factors: Age Age Genes Genes : Multifactorial: As Diabetes, Hypertension As Diabetes, Hypertension Cancer Cancer Etiology: What is the cause?

pathogenesis The sequence events in the response of the cells or tissues to the etiologic agent, from the initial stimulus to the ultimate expression of the disease,”from the time it is initiated to its final conclusion in recovery or death” The sequence events in the response of the cells or tissues to the etiologic agent, from the initial stimulus to the ultimate expression of the disease,”from the time it is initiated to its final conclusion in recovery or death” The core of the science of pathology — the study the pathogenesis of the disease.

Morphology: Structural Changes *Structural changes in disease. Tumor in a cancer. Ulcer in an infection. Atrophy in dementia. *Lesion: Demonstratable structural change produced in the course of the disease (gross level, microscopic level)

Manifestations *Subclinical Stage: Early in the development of the disease, the etiological agent may provoke a number of changes in biologic process that lab analysis can detect, even though the patient has no subjective symptoms. *Symptoms:Clinical symptoms are the patient’s complain usually by its own words. *Signs: are seen only in the living individual e.g. fever, tenderness, increased respiratory rate, etc.)” *Signs: when the observer can objectively identify manifestations of the disease. They are seen only in the living individual e.g. fever, tenderness, increased respiratory rate, etc.)”

*Sequelae: the outcome of the disease. *Complication: of the disease is a new or separate process that may arise secondarily because of some change that the original entity produce. *Resolution:when the host return to a completely normal state, without sequelae or complications (spontaneously from body defenses or from successful therapy). *Prognosis: Expected outcome of the disease, It is the clinician's estimate of the severity and possible result of a disease.

I hear, I forget I see, I remember I do, I understand Chinese Proverb..