Introduction to Pathology

Introduction to Pathology

• Pathology is the study of the structural, biochemical, and functional changes in cells, tissues, and organs that underlie disease
• The word 'Pathology' comes from two Greek words: pathos (meaning suffering) and logos (meaning study)
• Pathology consists of the abnormalities in normal anatomy (including histology) and normal physiology owing to disease
• ‘Pathophysiology’ combines 'patho' (suffering) and 'physiology' (study of normal function)
• Pathophysiology is the study of disordered function (i.e. physiological changes) and breakdown of homeostasis in diseases (i.e. biochemical changes).

Course Overview

• The course will cover the basic concepts and general mechanisms of cell and tissue reactions and disease processes
• This includes the most common etiological factors, pathogenesis, different morphological features and clinical manifestations
• Topics include cell injury, cellular adaptations, intracellular accumulations, inflammation, regeneration, tissue repair and healing
• The course will also address the most common pathology terminologies that are essential for the course.

Semester 1 Topics

• Cell injury
• Types of cellular adaptations
• Inflammation: Acute, chronic and granulomatous type
• Tissue repair and wound healing

Objectives

• To understand the major cellular and molecular changes which underlies a general disease process
• Apply these concepts into understanding of the specific diseases
• Identifying disease morphologies and outcome and correlating their clinical presentations with the disease process
• To recognize the etiology, pathogenesis and morphology of disease phenomena associated with cell injury, inflammation and tissue repair
• To understand the knowledge of microscopic features of the range of normality within tissues as well as the major common pathological processes and patterns of disease

Assessment

• There are six main assessment components for this course:
  • Quizzes 1 and 2
  • Lab requirements
  • Assignments
  • OSPE
  • Final Exam

Common Terminology in Pathology

• Patient: The person affected by the diseas
• Lesion: The characteristic changes in tissues and cells produced by disease
• Symptoms: Functional implications of the lesion felt by the patient
• Physical Signs: Functional implications discovered by the clinician
• Diagnosis: The clinical significance of the morphologic and functional changes together with results of other investigations help to arrive at an answer to what is wrong
• Prognosis: What is going to happen
• Treatment: What can be done about it (How to treat or manage)
• Prevention: What should be done to avoid complications and spread

Aspects of Disease Process

• Etiology: The cause for a disease (‘WHY’ of a disease)
• Pathogenesis: The mechanisms by which the lesions are produced (‘HOW’ of a disease)
• Morphology: The appearance of tissue or organ in a disease; changes recognized by the naked eye is ‘GROSS’ morphology and changes studied by microscopy is ‘MICROSCOPIC’ morphology
• Clinical Manifestation: Signs and symptoms of the disease

Disease Aspects

• Pathogenesis: The mechanisms by which the lesions are produced.
• Morphology: The structural alterations in cells or tissues that are characteristic of a disease and hence diagnostic of an etiologic process; includes gross and microscopic examination
  • Macroscopical (gross) lesions: Abnormality in the tissue can be described grossly or by the naked eye including location, color, size, shape, consistency & appearance of the cut surface.
  • Microscopy: Abnormal morphological changes described under the microscope.
  • Nonneoplastic lesions: Inflammatory: acute or chronic, Congenital disorders, Endocrine deficiencies, Hyper/Hypo, Infarction, Infections, Intracellular accumulations, Autoimmune diseases
  • Neoplastic lesions: Capsule, circumscription, Tumor cells : benign Vs malignant, If malignant: Histological type, Grade, Margins, Lymphovascular invasion, Status of lymph nodes

Subdivisions of Pathology

• General pathology: Concerned with the common reactions of cells and tissues to injurious stimuli; these reactions are often not tissue specific (e.g. acute inflammation in response to bacterial infections produces a very similar reaction in most tissues)
• Systemic pathology: Examines the alterations and underlying mechanisms in diseases of particular organ systems

Branches of Pathology

• Histopathology (Anatomic Pathology): The study includes structural changes (gross or macroscopic changes), and the changes detected by microscopy, to arrive at the most accurate diagnosis; Modern time anatomic pathology includes sub-specialities such as cardiac pathology, pulmonary pathology, neuropathology, renal pathology, gynaecologic pathology, breast pathology, dermatopathology
• Macroscopic pathology (Gross)
• Microscopic features
  • Surgical pathology: Deals with the study of tissues removed from the living body by biopsy or surgical resection
  • Experimental pathology: Production of disease in the experimental animal and study of morphological changes in organs after sacrificing the animal.
  • Forensic pathology and autopsy work: Includes the study of organs and tissues removed at postmortem for medicolegal work and for determining the underlying sequence and cause of death
• Cytology: Study of cells
  • Exfoliative cytology: Cells shed off from the lesions
  • Fine-needle aspiration cytology (FNAC): Cells aspirated from superficial and deep-seated lesions for diagnosis
• Clinical Pathology: Analysis of various fluids including blood, urine, semen, CSF and other body fluids; such analysis may be qualitative, semi-quantitative or quantitative.