Introduction to Pathology By Dr. Gehan Mohamed Dr. Abdelaty Shawky

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Introduction to PathologyByDr. Gehan Mohamed
Dr. Abdelaty Shawky
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• Pathology is the science which studies the
  nature of the disease.

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Pathology Classification

• General pathology
• The study of general reactions of cells and
  tissues to insults and injuries that are basic to
  all disease processes.
• Systemic pathology
• The study of specific disease processes or
  reactions as they affect particular organs or
  organ systems e.g. CVS, CNS, GIT..etc.

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Applied pathology

• 1. Anatomic pathology
• a. Necropsy pathology
• b. Surgical pathology
• c. Cytopathology
• 2. Clinical pathology.
• 3. Forensic pathology.

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• Anatomic Pathology
• Making diagnosis by examining tissues.
• Necropsy pathology
• Examination of tissues excised from cadavers in
  an effort to establish the cause of death.
• This is called autopsy.
• Surgical pathology
• Examination of tissues excised from living
  patients in an effort to establish a specific
  diagnosis.
• This is called biopsy.
• Cytopathology
• The microscpocic study of exfoliated cells within
  body fluids.

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• 2. Clinical pathology
• Analysis of various specimens (whole blood,
  serum, plasma, urine, stool, CSF, sputum, etc.)
  from patients to facilitate diagnosis, direct
  therapeutic approach and monitor therapy.
• 3. Forensic pathology
• Subspecialty dealing with medicolegal
  investigation of death.

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• Biopsy
• - Examination of tissues from the living body to
  determine the cause of a disease.
• a. Closed biopsy (needle or core biopsy)
• The pathologist or clinician put a needle into
  the mass to obtain a bit of tissue.
• Usually wont give you enough material.
• b. Open biopsy (incisional biopsy)
• - An incision was made to obtain a larger mass of
  tissue.
• c. Excisional biopsy
• - Excision of the whole mass for diagnosis.

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Needle or core biopsy
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Excisional biopsy
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FNAC Fine Needle Aspiration Cytology

• A thin core needle is used to obtain a few cells
  from a mass lesion.
• Used for
• Superficial mass
• Deep mass lesions (with help of CT/USG)

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FNAC
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The Disease

• The structural and functional changes in organs
  and tissues due to exposure to an irritant
  (causative agent of the disease).

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Classification of Diseases

• A. Developmental genetic, congenital.
• B. Acquired
• 1. Inflammatory .
• 2. Neoplastic e.g. Tumors
• 3. Degenerative e.g. Ageing.
• 4. Metabolic .

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What should we know about the disease?

• Definition.
• Epidemiology Where When.
• Etiology What is the cause?
• Pathogenesis Evolution of dis.
• Morphology Structural Changes
• Complications.
• Management
• Prognosis
• Prevention

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Etiology Study of the cause of a disease"

• a. Predisposing Causes of Disease
• Factors which make an individual more susceptible
  to a disease (damp weather, poor ventilation,
  etc.)
• b. Exciting Causes of Disease (An etiologic
  agent )
• Factors which are directly responsible for a
  disease (hypoxia, chemical agents , virus,
  bacteria . etc.). 

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Pathogenesis

• The sequence of events in the response of the
  cells or tissues to the etiologic agent, from the
  initial stimulus to the ultimate expression of
  the disease or simply the mechanism of disease
  occurrence.

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MORPHOLOGY OF THE DISEASE

• Gross (macroscopic) changes By naked eye
  examination.
• Histologic (microscopic) changes By light
  microscope examination.
• Ultrastructural changes By an electron
  microscope examination.

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• (1). Gross appearance
• Size.
• Shape.
• Weight.
• Color.
• Consistency.
• Surface.
• Edge, section.

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• (2). Microscopic examination
• for tissue sections fixed in formalin then
  stained by HE (hematoxylin and eosin) to be
  examined by light microscope.
  Fatty liver

Normal liver
Fatty liver
Hemangioma
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Prognosis

• Expected outcome (fate) of the disease.
• Good prognosis suggests recovery is likely.
• Poor prognosis suggests permanent disability or
  death.

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Welcome to Pathology