Pathology CAM235
Unit 1
Introduction
‫علم األمراض‬
Dr. Raid Al-Baradie
PATHOLOGY - Definition
Pathology is the study (logos) of suffering (pathos).
It is a discipline ‫ انضباط‬that bridges clinical practice and
basic science
Pathology is Scientific study of disease.
More specifically, pathology may be defined as the "scientific
study of the molecular, cellular, tissue, or organ system in
response to injurious agents or adverse influences."
DISEASE
Disease is defined as any disturbance of the structure and/or
function of the body or any of its constituent parts outside the
normal range, especially one that produces specific clinical signs.
Nearly every disease is associated with dysfunction ‫اختالل‬
‫ وظيفي‬at the level of the organ, cell, or organelle.
This allows the pathologist
‫ الطبيب الشرعي‬to identify
functional damage and the cascade ‫ تتالي‬of disease
processes on the basis of abnormal structural changes.
PATHOLOGICAL STUDY OF DISEASE
• It involves the investigation of the causes (etiology,
‫ السبب )علم أسباب األمراض‬of disease as well as the underlying
mechanisms ‫( آلية‬pathogenesis) that result in the presenting signs
‫ عالمات‬and symptoms ‫ األعراض‬of the patient
CHARACTERISTICS OF DISEASE
1. Etiology : This involves the study of pathogens that cause disease
‫علم أسباب األمراض‬
2. Pathogenesis: the mechanism causing the disease
This answers the question of why a certain pathogen causes disease
in a certain individual.
Sequence of events in the response of cells or tissues to an etiological
agent, starting from the initial stimulus to the ultimate expression of
disease, without any treatment
3. Morphology: the structural features of the disease
4. Clinical Significance: the functional features of the disease
ETIOLOGY
• “Study of the cause of a disease"
• An etiologic agent is the factor (bacterium, virus, etc.)
responsible for lesions or a disease state.
• Predisposing Causes of Disease: Factors which make an
individual more susceptible to a disease (damp weather, poor
ventilation, etc.)
• Exciting Causes of Disease: Factors which are directly
responsible for a disease (bacteria, viruses, hypoxia, chemical
agents, etc.).
MORPHOLOGICAL CHANGES
AUTOPSIES
Autopsy (necropsy and postmortem examination are synonymous)
means to 'see for oneself'.
In other words, rather than relying on clinical signs and symptoms
and the results of diagnostic investigations during life, here is an
opportunity for direct inspection and analysis of the organs.
Autopsies are useful for:
i. determining the cause of death
ii. audit of the accuracy of clinical diagnosis
iii. education of undergraduates and postgraduates
iv. research into the causes and mechanisms of disease
v. gathering accurate statistics about disease incidence.
‫المتصورة‬
‫الهدف الحقائق‬
‫حاد‬
‫مزمن‬
‫نتائج‬
‫تنبؤ‬
NOMENCLATURE OF DISEASE
1. Primary and secondary
They may be used to describe the causation of a disease.
Primary means that the disease is without evident cause. Example,
primary hypertension is defined as abnormally high BP without
apparent cause.
Secondary means that the disease represents a complication of some
underlying lesion. Example, secondary hypertension is defined as
abnormally high BP as a consequence of some other lesion (e.g. renal
artery stenosis).
The words primary and secondary may be used to distinguish
between the initial and subsequent stages of a disease, most
commonly in cancer.
NOMENCLATURE OF DISEASE
2. Acute and chronic
Acute and chronic are terms used to describe the dynamics of a
disease.
Acute conditions have a rapid onset, often but not always followed
by a rapid resolution.
Chronic conditions may follow an acute initial episode, but often are
of deceptive onset, and have a prolonged course lasting months or
years.
Subacute, a term not often used now, is intermediate between acute
and chronic.
NOMENCLATURE OF DISEASE
3. Benign and malignant
Benign and malignant are emotive terms used to classify certain
diseases according to their likely outcome. Thus,
Benign tumours remain localised to the tissue of origin and are very
rarely lethal unless they compress some vital structure (e.g. brain),
whereas malignant tumours invade and spread from their origin and
are commonly lethal.
Benign hypertension is relatively mild elevation of blood pressure
that develops gradually and causes insidious injury to the organs of
the body.
This situation contrasts with malignant hypertension, in which the
blood pressure rises rapidly and causes severe symptoms and tissue
injury (e.g. headaches, blindness, renal failure, cerebral
haemorrhage).
NOMENCLATURE OF DISEASE
4. Eponymous names
An eponymous disease or lesion is named after a person who first
described the condition. Examples include:
i. Graves' disease: primary thyrotoxicosis
ii. Paget's disease of the nipple: infiltration of the skin of the nipple
by cells from a cancer in the underlying breast tissue
iii. Crohn's disease: a chronic inflammatory disease of the gut
affecting most commonly the terminal ileum and causing
narrowing of the lumen
iv. Hodgkin's disease: a neoplasm of lymph nodes characterised by
the presence of Reed-Sternberg cells
v. Reed-Sternberg cells: large cells with bilobed nuclei and
prominent nucleoli which are virtually diagnostic of Hodgkin's
disease.
NOMENCLATURE OF DISEASE
5. Syndromes
A syndrome is an aggregate of signs and symptoms or a
combination of lesions without which the disease cannot be
recognised or diagnosed. Examples :
Cushing's syndrome: hyperactivity of the adrenal cortex resulting
in obesity, hirsutism, hypertension, etc.
Nephrotic syndrome: albuminuria, hypoalbuminaemia and
oedema; this syndrome can result from a variety of glomerular and
other renal disorders.
EPIDEMIOLOGY OF DISEASE
Epidemiology is the study of disease in populations.
It also concerns the identification of the causes and modes of
acquisition of disease.
Epidemiology involves the recording and analysis of data about
disease in groups of people rather than in the individual person
alone.
Knowledge about the occurrence of a disease is important for:
a) providing etiological clues
b) planning preventive measures
c) provision of adequate medical facilities
d) population screening for early diagnosis.
MAKING DIAGNOSES
Diagnosis is the act of naming a disease in an individual
patient.
The diagnosis is important because it enables the patient to
benefit from treatment that is known, or is at least likely, to
be effective from having observed its effects on other
patients with the same disease.
The process of making diagnoses involves:
i. taking a clinical history to document symptoms
ii. examining the patient for clinical signs
iii.if necessary, performing investigations
GOAL ‫ الهدف‬OF PATHOLOGY
The ultimate goal of pathology is the identification of the
causes of disease, a fundamental objective leading to
successful therapy and to disease prevention.
BRANCHES OR PHASES OF PATHOLOGY
Traditionally, the discipline is divided into general pathology and
systemic pathology;
• GENERAL PATHOLOGY: This focuses on the fundamental cellular
and tissue responses to pathologic stimuli (e.g. inflammation,
tumours, degenerations)
• SYSTEMATIC PATHOLOGY: The descriptions of specific diseases
as they affect individual organs or organ systems (e.g.
appendicitis, lung cancer, atheroma).
SUBDIVISIONS OF PATHOLOGY
GROSS PATHOLOGY (macroscopic pathology, pathological anatomy,
morbid anatomy):
Refers to the study of disease in which tissues and organs are examined with the
unaided eye.
CELLULAR PATHOLOGY (microscopic pathology, histopathology):
Refers to the study of diseased tissues and organs with the aid of a microscope.
SURGICAL PATHOLOGY:
Refers to the study of tissues removed at the time of surgery.
CLINICAL PATHOLOGY:
Refers to the study of disease by examination of blood, urine, feces, skin
scrapings, etc.
IMMUNOPATHOLOGY:
Refers to the study of diseases associated with abnormalities of the immune
mechanisms of the body.
TECHNIQUES OF PATHOLOGY
1. Gross pathology – macroscopic investigation and
observation of disease
2. Light microscopy – thin section of wax or plastic
permeated tissues, snap-frozen tissues
3. Histochemistry – microscopy of treated tissue sections (to
distinguish cell components)
4. Immunohistochemistry and immunofluorescence –
tagged antibodies (monoclonal better)
5. Electron microscopy
6. Biochemical techniques – e.g. fluid and electrolyte
balance, serum enzymes
7. Cell cultures – also allowing cytogenetic analysis
8. Medical microbiology – direct microscopy, culturing and
identification
9. Molecular pathology – in situ hybridisation (specific
genes/mRNA), polymerase chain reaction
Unit 1 Objectives
At the end of this chapter you should be able to answer the
following question
1. Define Pathology?
2. What is disease?
3. Write the characteristics of disease?
4. What do you mean by etiology and pathogenesis?
5. Define the 2 main cause of disease?
6. Write the methods for studying the morphological
alterations in tissues?
7. How is autopsy useful?
8. Define symptom, onset and prognosis of disease?
Unit 1 Objectives
9. Write the difference between
(a) Primary and secondary disease
(b) Acute and Chronic disease
(c) Benign and Malignant disease
10. What is Syndrome? Give 2 examples?
11. Define epidemiology and write the importance of
epidemiology?
12. Write the process of making diagnosis of disease?
13. Define the 2 branches of Pathology?
14. What are the subdivision of pathology?
15. Name the techniques used to study pathology?
16. What is diagnosis?
17. Write the process of making diagnosis of disease?