Introduction to Pathology

Introduction to Pathology

• Pathology is the study of disease using scientific methods.
• It examines changes in cells and tissues due to injury.
• Disease is defined as an abnormality in structure or function of any body part (physiological or psychological dysfunction).
• Pathology of any disease involves 5 main aspects.

Parts of Pathology

• Epidemiology: The study of disease occurrence and distribution within a population. It examines patterns, causes, and effects of disease in various populations. Epidemiological factors include sex, age, race, occupation, geographic location, and socioeconomic status.
• Etiology: The cause of a disease. If unknown, the disease is considered idiopathic/cryptogenic/essential.
• Pathogenesis: The sequence of steps causing tissue injury due to a problem in the body. Four basic mechanisms: inflammatory process, degenerative process, carcinogenesis (transformation of normal cells to malignant), and immunological process.
• Morphological Changes: Structural changes in cells or tissues due to disease. Changes may be macroscopic (visible with the naked eye) or microscopic (observable with a microscope). Microscopic and macroscopic examinations help diagnose the disease.
• Clinical Features: Signs and symptoms of a disease. Symptoms are experienced by the patient, while signs are observed by a physician during examination (e.g., swelling, enlarged organs). Clinical features are the combination of signs and symptoms.
• Prognosis: The predicted outcome of a disease. It's based on the severity of the disease, categorized as well (patient improving) or poor (patient deteriorating potentially to death).
• Morbidity: Presence of illness.
• Mortality Rate: Number of deaths in a population during a specific time period. High mortality rates commonly occur in high-grade cancers.
• Sequelae: Complications or consequences of a disease that occur after the initial illness.

Purposes of Epidemiology

• Investigating the prevalence of a disease within a community.
• Studying the natural history and prognosis of disease.
• Identifying the causes and risk factors of a disease (e.g., chronic smoking and lung cancer).
• Providing better healthcare based on findings.
• Recommending and assisting with health programs.
• Evaluating healthcare facilities and programs.
• Developing public health policies.

Etiology and Classification of Disease

• Etiology in pathology is the cause of a disease.
• Diseases are categorized based on their etiology and pathogenic mechanisms.
• Diseases can be congenital (present from birth) or acquired.

Clinical Features (Functional Alteration)

• Damage to an organ can alter its normal function, leading to symptoms and signs.
• Symptoms are patient-reported experiences (e.g., headache, tiredness).
• Signs are physician-observed findings (e.g., swelling, enlarged organs).
• Signs and symptoms together comprise clinical features.