Introduction to Pathology PDF

INTRODUCTION ▪ PATHOLOGY (from the Ancient Greek roots of pathos (πάθος), meaning "experience" or "suffering" and -logia (-λογία), "study of") ▪ It is a significant field in modern medical diagnosis and medical research, concerned mainly with the causal study of disease, whether caused by pat...

INTRODUCTION ▪ PATHOLOGY (from the Ancient Greek roots of pathos (πάθος), meaning "experience" or "suffering" and -logia (-λογία), "study of") ▪ It is a significant field in modern medical diagnosis and medical research, concerned mainly with the causal study of disease, whether caused by pathogens or non-infectious physiological disorder. ▪ WHAT IS THE PATHOLOGY? - Pathology is the study of disease. - In the broadest sense, it is the study of How the organs and tissue of healthy body change to those of a sick person. ▪ Pathology is a branch of medical science that involves the study and diagnosis of disease through the examination of surgically removed organs, tissues (biopsy samples), bodily fluids, and in some cases the whole body (autopsy). ▪ The study of pathology Therefore provides understanding of the disease processes and constitutes a scientific basis of medicine. ▪ Traditionally, the study of pathology is divided into : 1. GENERAL PATHOLOGY (Principles of diseases) 2. SYSTEMIC PATHOLOGY. GENERAL PATHOLOGY: ▪ It is concerned with the basic reactions of cell and tissues to abnormal stimuli that underline all diseases.. SYSTEMIC PATHOLOGY: ▪ It is the study of the pathological aspects of all diseases affecting specialized tissue (the different organs or body system)  ANATOMICAL PATHOLOGY is a medical specialty that is concerned with the diagnosis of disease based on the gross, microscopic, chemical, immunologic and molecular examination of organs, tissues, and whole bodies (as in a general examination or an autopsy) THE MAIN ASPECTS OF DISEASE THAT FORM THE CORE OF PATHOLOGY ARE : 1. Definition and categorization of the disease 2. Etiology : the cause or causes of the disease 3. Pathogenesis: the mechanisms of development of the disease. 4. Mophologic Changes(Pathological features): (a) Gross Changes (b) Microscopic Changes 5. The Functional Consequences : of the morphologic changes including the clinical effects, fate (i.e) course and prognosis of the disease as well as possible complications. A. GROSS CHANGES : ▪ They are also called naked eye changes or macroscopic changes and include all changes that can be detected by the naked eye such as : Change in size, colour and consistency. B. MICROSCOPIC CHANGES : ▪ These are cellular and/or extracellular changes that characterize each disease and commonly help in detecting the etiology. ▪ Few examples are given here as detection of: Malignant cells, Inflammatory cell, Vascular thrombosis, Bilharzia ova, Fungal coloni…..etc HISTOPATHOLOGY ▪ Histopathology refers to the microscopic examination of various forms of human tissue. ▪ Specifically, in clinical medicine, histopathology refers to the examination of a biopsy or surgical specimen by a pathologist, after the specimen has been processed and histological sections have been placed onto glass slides. ▪ Histopathological examination of tissues starts with surgery, biopsy, or autopsy. The tissue is removed from the body then placed in a fixative that stabilizes the tissues to prevent deterioration. ▪ The most common fixative is formalin, although frozen section fixing is also common. ▪ To see the tissue under a microscope, the sections are stained with one or more pigments. The aim of staining is to reveal cellular components. ▪ Histochemistry refers to the science of using chemical reactions between laboratory chemicals and components within tissue. ▪ The histological slides are then interpreted diagnostically, and the resulting pathology report describes the histological findings and the opinion of the pathologist. ▪ In the case of cancer, this represents the tissue diagnosis required for most treatment protocols. CONSEQUENCES OF CELL INJURY: (OF CELL & TISSUE) 1. Reversible cell injury (Degeneration) 2. Irreversible cell injury a) Necrosis. b) Apoptosis. 3. Cellular adaptations of growth and differentiation: a) Atrophy. b) Hypertrophy. c) Hyperplasia d) Metaplasia 4. Intracellular accumulation (as fat, proteins, carbohydrates and pigments) - These accumulations may sometimes be the cause of cell injury, but in other instances they may result from cell injury. 5. Extracellular depositions as calcification. 6. Inflammation and Repair 7. Vascular disturbances as thrombosis and oedema 8. Abnormalities of cell growth : (a) Dysplasia (b) Neoplasia (tumors)