Introduction to Pathology

Introduction to Pathology

• Pathology is the science that studies the nature of disease.
• Pathology classifications include general and systemic pathology.
• General pathology studies the fundamental responses of cells and tissues to injury in all disease processes.
• Systemic pathology focuses on specific disease processes affecting particular organs or organ systems (e.g., cardiovascular system, central nervous system, gastrointestinal tract).

Applied Pathology Classification

• Necropsy pathology examines tissues from deceased individuals to determine the cause of death; this is called "autopsy."
• Surgical pathology examines tissues from living patients to establish a specific diagnosis; this is called "biopsy."

Biopsy Methods

• Needle or core biopsy: A needle is inserted into a mass to collect a tissue sample. This method may not yield enough material for analysis.
• Incisional biopsy: A larger tissue sample is collected using an incision.
• Excisional biopsy: The entire mass is removed for analysis.

Classification of Pathology by Specimen Type

• Histopathology: Examination of tissues for diagnosis.
• Cytopathology: Microscopic study of exfoliated cells from body fluids.

Fine Needle Aspiration Cytology (FNAC)

• FNAC is a technique using a thin needle to obtain cells from a mass for cytological analysis.
• It is used for both superficial and deep-seated masses (with guidance from radiology).

The Disease

• Disease involves structural and functional changes within organs and tissues caused by an irritant or causative agent.

Classification of Diseases

• Hereditary diseases arise from chromosomal abnormalities or gene mutations.
• Acquired diseases include inflammatory conditions, neoplasms (tumors), degenerative conditions (like aging), and metabolic disorders.

Items of Study for Diseases

• Definition
• Etiology (cause)
• Pathogenesis (mechanism)
• Morphological features (observable characteristics)
• Complications
• Prognosis (expected outcome)

Etiology of a Disease (Cause of Disease)

• Predisposing causes: Factors that make a person more prone to a disease (e.g., heredity, low immunity)
• Exciting causes: Factors directly responsible for the disease (e.g., infection)

Pathogenesis of a Disease (Mechanism)

• Describes how an etiologic agent causes the disease.

Morphology of a Disease

• Gross picture: Examination of the tissue by the naked eye (size, shape, color, consistency, cut section).
• Microscopic picture: Examination of tissue sections under a microscope. This is used to determine the nature of a disease.

Complications of a Disease

• Pathological changes that occur after the initial disease course has run its usual course.
• Examples include a cold progressing to bronchitis, or bronchitis progressing to pneumonia.

Prognosis of a Disease

• The expected outcome or fate of the disease, which may be good or poor, suggesting either likely recovery or potential disability or death.

References

• Robbins and Cotran Pathologic Basis of Disease, 9th edition, 2014 (Kumar, Abbas, Aster)
• Robbins Basic Pathology 10th edition, 2017 (Kumar, Abbas, Aster)

Explore the fundamentals of pathology, including its classification into general and systemic pathology. This quiz will cover key concepts like necropsy and surgical pathology, as well as various biopsy methods used for diagnosis. Test your understanding of disease processes and tissue examination techniques.