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Introduction to pathology By Dr. Fatma El.Zahraa Mohammed El.Saoudy Consultant of Clinical Pathology Assiut University objectives Define the term pathology Understand the term etiology Know the predisposing factors and classification of diseases...

Introduction to pathology By Dr. Fatma El.Zahraa Mohammed El.Saoudy Consultant of Clinical Pathology Assiut University objectives Define the term pathology Understand the term etiology Know the predisposing factors and classification of diseases Understand the pathogenesis of a disease Define the terms fate and complications know how to study and why we study pathology Identify types of pathological specimens and how it is prepared and examined What is pathology? Pathology The scientific study of disease (pathos=suffering, logos=study) It involves the study of the structural and functional changes at the level of cells, tissues and organs. Disease is defined as an abnormality in structure or function of any part of the body. Homeostasis: self-regulating process by which biological systems tend to maintain stability while adjusting to conditions that are optimal for survival Pathology Is divided to general and systemic pathology General pathology: It deals with the study of mechanism, basic reactions of cells and tissues to abnormal stimuli and to inherited defects. Systemic pathology: This deals with the changes in specific diseases/ responses of specialized organs and tissues. Major aspects of pathology Major aspects of pathology of any disease: Definition Epidemiology Etiology Pathogenesis Morphologic changes Functional implications (Clinical features) Prognosis Scientific Study of Disease Definition: Each disease has a definition E.g., An abscess is a localized suppurative inflammation Epidemiology Study of the occurrence and distribution of diseases in a population and the application of this knowledge to help the health system. It is the study of the patterns, causes, and effects of disease conditions in various populations. Epidemiology studies provide information regarding the following factors: a. Sex b. Age c. Race d. Occupation: 1.workers in asbestos industry can have diseases like asbestosis or tumors like mesotheliomas. 2.workers in aniline dye industry can have urinary bladder cancer. 3. hardwood workers can have nasal cancer from inhalation of wood dust etc. b. Geographic location: which part of the world a particular disease is common in, e.g: 1.underdeveloped countries has more malnutrition and infections like tuberculosis. 2.developed countries have more cardiac problems, obesity related diseases etc. Scientific Study of Disease Etiology: is the origin of a disease, including the underlying causes, and predisposing factors. Causes: The causative factors ( Exciting factor) of a disease can be divided into two major categories: genetic and acquired (e.g., infectious, chemical, hypoxia, nutritional, physical). Predisposing factors Brings the body under the influence of the direct cause. E.g., a small abrasion in the skin may predispose to the entry of organisms and abscess formation. Classification of Diseases idiopathic/cryptogenic/ essential : If the cause of the disease is unknown Congenital Acquired -inflammatory -vascular -growth disorder -metabolic -degenerative -drug induced -infective CONGENITAL DISEASE ACQUIRED DISEASE Definition: it Is a condition existing at birth or before birth, or Inflammatory: e.g., rheumatoid arthritis, that develops during the first month of life. dermatitis(eczema). Infective: bacterial, viral, fungal. Genetic/ chromosomal: e.g., Vascular: e.g., atherosclerosis (heart attack) or Immune mediated e.g., vasculitis etc. hemophilia (an x chromosome linked disorder, reduction or absence of blood clotting factor) Degenerative: e.g., Alzheimer’s and Parkinsonism. Down syndrome (chromosomal abnormality with Neoplastic disorder: e.g., cancer extra chromosome 21). Therapeutic or drug associated disease: e.g., cystic fibrosis(autosomal recessive). inborn error of certain drugs can cause liver or kidney failure, metabolism, defective epithelial ion transport bone marrow suppression, skin rash. Alcohol can mechanism causes thick, sticky mucous secretions. cause liver disease Metabolic: e.g., gout, diabetes mellitus, kidney stones Non-genetic: an abnormal defect or deformity a child is born with e.g., a birth defect like cleft lip or Nutritional: deficiency diseases e.g., anemia, spina bifida etc. protein energy malnutrition etc. Radiation: radiation to neck can cause thyroid cancer or radiation to skin can causes skin cancer (squamous cell carcinoma) etc. Mechanical: e.g. road traffic accident Scientific Study of Disease Pathogenesis: It refers to the mechanism ( steps) by which the causative factor/s produces structural and functional abnormalities in cells, tissue or organs (A lesion). Pathogenesis refer to sequence of events that occur in the cells or tissues from the initial stimulus to the expression of the disease. Morphologic changes: All diseases start with structural changes in cells. Rudolf Virchow (known as the father of modern pathology) proposed that injury to the cell is the basis of all disease. Morphologic changes: refer to the gross and microscopic structural changes in cells or tissues affected by disease. Gross changes: includes changes in size, shape, color, cut surface and consistency of the diseased organ. Microscopic Changes: Abnormalities in tissue architecture and morphological changes in cells can be studied by light microscope  Scientific Study of Disease Functional implications of the lesion felt by the patient are symptoms and those discovered by the clinician are the physical signs 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 am feeling tired’ , ‘I have a headache’, ‘I have a pain in my stomach’ etc. (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 swelling somewhere or doctor find a liver or spleen enlargement while examining the abdomen etc. (it is what the doctor will find on examining the patient). The combination of signs and symptoms is called as clinical features. Scientific Study of Disease Fate: It refers to the course (outcome) of the disease. Regression (good fate) Progression with complications (bad fate) Prognosis: The prediction of how the patient’s disease will progress Complications: It is a negative pathologic process or event occurring during the disease which is not an essential part of the disease. It usually aggravates the illness. E.g. perforation and hemorrhage are complications which may develop in typhoid ulcer of intestine Sequelae: It is a pathologic condition following as a consequence of a disease. E.g. intestinal obstruction following healed tuberculosis of intestine, mitral stenosis following healed rheumatic heart disease Outcome and consequences of disease: Following clinical onset, disease may follow any of the following trends: -Recovery/resolution of disease without complication or sequalae. Person is back to normal health. -The disease recovery but with sequelae -Complications: Development of complications in any disease can make things worse. -Death Why we study pathology? To describe to medical students the disease process to be able to correlate the clinical manifestations with the pathological changes that occurs in the diseased organ. To predict the course and outcome (fate and prognosis)of various diseases. To realize the role of histopathology and diagnostic cytology in the diagnosis and treatment of diseases THE BRANCHES/SUBDIVISIONS OF PATHOLOGY pathologic diagnosis 1.Clinical data: A detailed clinical history including family history (social and occupational), diet and geographic origin. Physical examination, including detection of a mass lesion. 2.Histopathologic diagnosis (biopsy) 3.Cytopathology Fine needle aspiration cytology (FNAC): Aspiration of fluid or cells from the lesion Exfoliative cytology: shed cells from the lesion Brush cytology Thank you