This is an interesting guide to pathology for students and serve as a reference for research.

1. INTRODUCTION TO
PATHOLOGY.
BY SILAS MKOMBE
1

2. Pathology.
2
 This course is designed to enable the learner
comprehend the mechanisms by which
disease processes alter the normal body
structure and function.

3. Objectives.
3
 Define basic terms and concepts in pathology
 Classify diseases and disorders
 Explain various pathological processes

4. Definition.
4
 The word Pathology has two words- pathos and
logus where pathos means disease and logus is
discourse therefore pathology means disease
discourse
 Pathology can be defined as: -A natural science
that encompasses the study of abnormal
condition of the body as in causes, nature,
evolution, morphological and functional
changes that occur thereof
 Pathology is the backbone of evidence based
medicine.

5. Terminology
5
 Aetiology - Causal factors (“why” of disease
– the cause of disease)
 Lesion - Structural alterations in tissues
that give rise to functional abnormalities)
- Characteristic changes in tissues
and cells produced by a disease
 Morphology - structure or shape

6. Cont
6
 Natural history - Course of disease from the
beginning to the end without treatment
 Organic disease - Disease associated with
structural changes
 Functional disease - Disease with functional
abnormalities but no structural abnormalities

7. Cont.
7
 Pathologic anatomy - Study of changes in
structure and morphology
 Pathogen - An organism or substance that can
cause disease
- Disease producing agent (restricted
to living agent
 Pathogenesis - Is the origin and development of
disease including factors that influence it.
- Mechanisms by which lesions are
produced

8. cont
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 Pathogenesity - The capacity to produce
disease
 Pathognomonic - Describes anything that is
typical of a particular disease
 Patient - Person affected by disease

9. cont
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 Prognosis - The prediction of outcome of the
disease which is based on the Knowledge of
natural history and response to treatment
- An opinion concerning the eventual outcome
of the disease
 Symptoms - Subjective complains
(manifestations) from a patient
 Signs - Physical/objective findings

10. The knowledge of Pathology
enables: -
10
 The learner to explain the signs and
symptoms of the various disease conditions
exhibiting the understanding of aetiology,
pathophysiology and pathology of the
disease.
 One to learn the mechanisms by which
normal anatomy and physiology is altered by
pathological processes.

11. Cont.
11
 One to develop basic knowledge of disease
process and how these relate to the signs
and symptoms, how the disease develops in
the absence of therapy and how therapy may
alter these processes.
 One to be able to accurately predict
complications and prognosis of the disease.
 Investigations and interpretations of results

12. Branches and subdivisions in
pathology
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 There are various disciplines of pathology
such as human pathology, animal pathology,
plant pathology, veterinary pathology, poultry
pathology etc.
 Human pathology is the largest branch of
pathology and is divided into General
pathology that describes general principles of
disease and systemic/clinical pathology that
studies diseases pertaining to specific organs
and body systems.

13. Cont.
13
 Histopathology (anatomic pathology or morbid
anatomy)
 Studies structural changes observed by the
naked eye examination (gross or macroscopic
changes).
 Changes detected by light or electron
microscope with the assistance of staining
procedures (microscopy)
 Has super specialities such as cardiac
pathology, renal pathology, dermopathology
etc

14. Cont.
14
 Has there main divisions
Surgical pathology – study of tissues
removed from the living body e.g. lymph
node, tumour mass
Forensic pathology and autopsy work –
study of organs and tissues removed at
post-mortem
Cytopathology – study of cells shed off
from lesions (exfoliative cytology) and
fine needle aspiration cytology (FNAC) of
superficial and deep-seated lesions

15. Cont.
15
 Haematology – diseases of blood e.g.
sickle cell disease, anaemia
 Immunology – abnormalities of
immune system (immunology and
immunopathology)

16. Principles of diagnosis
16
 Diagnosis is the procedure of
determining the nature and cause of a
patient’s illness by a clinician.
 It is based on the clinician’s evaluation of
the patient’s symptoms , signs and
results of various laboratory tests and
other appropriate diagnostic
procedures.

17. Cont.
17
 The symptoms are detected by the
process of history taking while the
signs are detected by the process of
physical examination which has
various components.
 After making a diagnosis, the clinician
can determine the prognosis and
institute treatment.

18. 1. History
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 Clinical history is a very important part of
evaluation
 Consists of several parts namely: -
 History of patient’s current illness
 The past medical history
 The family history
 The social history
 The review of systems (systemic enquiry)

19. 2. Physical examination
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Physical examination is a systematic
examination of the patient
Clinician should place particular
emphasis on the part of the body
affected by the illness
Abnormalities defected are correlated
with the clinical history

20. Cont.
20
Consider various diseases or conditions
that would fit the findings (differential
diagnosis)
Physical examination entails general
examination and systemic examination
The four physical examination
techniques are inspection, palpation,
percussion and auscultation.

21. 3. Treatment
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 Specific treatment
Exerts a highly specific and favourable
effect on the basic cause of the disease
 Symptomatic treatment
Aims at making the patient more
comfortable by alleviating symptoms but
does not have influence on the course of
the underlying disease

22. 4. Diagnostic tests and
procedures
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 There are a wide array of diagnostic tests and
procedures available to help the clinician make
a diagnosis and treat the patient properly.
 They are classified into 2 main groups namely:
-
i. Invasive produces
ii. Non-invasive procedures

23. Cont.
23
 Invasive procedures involve actual invasion
of the body in some way to obtain diagnostic
information e.g. introducing needles, catheters,
trochers and other instruments into the
patient’s body.
 Non-invasive procedures do not involve
invasion of the body and have no risk or
minimal risk or discomfort to the patient e.g
chest X-Ray (CXR) and urinalysis

24. Cont.
24
Classification of diagnostic tests and
procedures
1) Clinical laboratory tests
2) Tests that measure the electrical activity of
the body e.g. electrocardiography (ECG) and
electroencephalography (EEG)
3) Tests using radioisotopes (radionuclides)
4) Endoscopy

25. Cont.
25
1) Ultra sound procedures
2) X-ray examination
3) Magnetic resonance imaging ( MRI)
4) Position emission tomography(PET
scans)
5) Cytological and Histological
examinations

26. Cont.
26
CLASSIFICATION OF DISEASES
 Diseases fall into several large categories
according to lesions produced by the various
diseases.
 There are two ways of classification: -
 Based on morphology and pathogenesis
 International statistical classification of
Diseases (ICD 10)

27. 1. Classification according to
Morphology and Pathogenesis
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 In this type of classification there are five
broad groups namely: -
 Congenital and hereditary diseases
 Inflammatory diseases
 Degenerative diseases
 Metabolic diseases
 Neoplastic diseases

28. Cont.
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A. CONGENITAL AND HEREDITARY
DISEASES
 Result from disturbances of development
during the foetal life due to genetic
abnormalities, abnormalities in numbers and
distribution of chromosomes
 Caused by intrauterine injury from various
agents (e.g. X-rays, radioactive rays, infection)
or interaction of genetic and environmental
factors.

29. Cont.
29
 Examples
 Sickle cell disease – abnormal haemoglobin
 Haemophilia
 Congenital heart disease due infection with
German measles
 Down’s syndrome (Mongolism)
 Turner’s syndrome

30. Cont.
30
B. INFLAMMATORY DISEASES
 Inflammatory diseases are those conditions in
which the body reacts to an injurious agent by
means of inflammation.
 Examples
 Pneumonia
 Allergic reactions

31. Cont.
31
C. DEGENERATIVE DISEASES
 In degenerative diseases the primary
abnormality is a degeneration of various parts
of the body.
 Examples
 Aging in old individuals
 Joint diseases – arthritis
 Hardening of arteries - arteriosclerosis

32. Cont.
32
D. METABOLIC DISEASES
 In this class of diseases the cardinal
abnormality is a disturbance with some
important metabolic process in the body.
 Examples
 Diabetes mellitus
 Hypoglycaemia
 Thyrotoxicosis

33. Cont.
33
E. NEOPLASTIC DISEASES (CANCERS)
 Neoplastic diseases are characterized by
abnormal cell growth that leads to formation of
various types of tumours (cancers), which are
usually abnormal in structure and function.
 Examples
 Cancer of the breast, cervix, stomach,
oesophagus, uterus, ovary.

34. 2. ICD –10 CLASSIFICATIONS
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 This is an internal statistical classification of
diseases and related health problems that is
based on families and sets the International
nomenclature of diseases (IND).
 It takes into account of: -
 Diagnoses
 Symptoms and signs
 Abnormal laboratory findings
 Body systems affected
 Injuries and disabilities

35. Cont.
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A. INFECTIOUS AND PARASITIC
INFECTIONS (A00 – B99)
 Examples
 A00 Cholera
 A01 Typhoid and paratyphoid fevers
 A03 Shigellosis
 A06 Amoebiasis
 A09 Diarrhoea and gastroenteritis of
infectious origin

36. Cont.
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 A15 Respiratory tuberculosis confirmed
bacteriologically and histologically
 A16 Respiratory tuberculosis not
confirmed bacteriologically and histologically
 A17 TB of the nervous system
 A19 Milliary TB
 A22 Anthrax
 A23 Brucellosis
 A50 Congenital syphilis

37. Cont.
37
B. NEOPLASMS (C00 – D48)
 C46 Kaposi's sarcoma
 C50 Malignant neoplasm of the breast
 C67 Malignant neoplasm of the bladder
 D05 Carcinoma in situ of breast

38. Cont.
38
C. DISEASES OF BLOOD AND BLOOD
FORMING ORGANS (D50 – D89)
 D50 Iron deficiency anaemia
 D51 Vitamin B12 deficiency anaemia
 D52 Folate deficiency anaemia
 D57 Sickle cell disease

39. Cont.
39
D. ENDOCRINE, NUTRITIONAL AND
METABOLIC DISEASES (E00-E90)
 E05 Thyrotoxicosis (hyperthyroidism)
 E10 Insulin dependent diabetes mellitus
 E11 Non-insulin dependent diabetes
mellitus
 E15 Non-diabetic hypoglycaemic coma

40. Cont.
40
 E24 Cushing’s syndrome
 E40 Kwashiorkor
 E41 Nutritional marasmus
 E42 Marasmic kwashiorkor
 E55 Vitamin D deficiency
 E66 Obesity

41. Cont.
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E. MENTAL AND BEHAVIOURAL DISORDERS
(F00 – F99)
 F20 Schizophrenia
 F70 Mild mental retardation
 F71 Severe mental retardation

42. Cont.
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F. DISEASES OF THE NERVOUS SYSTEM
(G00 –G99)
 G00 Bacterial meningitis
 G20 Parkinson’s diseases
 G40 Epilepsy

43. Cont.
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 G41 Status epilepticus
 G43 Migraine
 G51 Facial nerve disorders
 G81 Hemiplegia
 G82 Paraplegia and tetraplegia
 G91 Hydrocephalus

44. Cont.
44
G. DISEASES OF THE EYE AND ADNEXA
(H00 – H59
 H10 Conjunctivitis
 H25 Senile cataract
 H40 Glaucoma

45. Cont.
45
H. DISEASES OF THE EAR AND MASTOID
PROCESS (H60 –H95)
 H60 Otitis externa

46. Cont.
46
DISEASES OF THE CIRCULATORY SYSTEM
(I00-I99)
 Diseases of the Respiratory system
 Diseases of the Digestive system
 Diseases of the skin and subcutaneous
tissues
 Diseases of the Musculoskeletal system and
connective tissue

47. Cont.
47
 Diseases of the Genito-urinary system
 Pregnancy, childbirth and the puerperium
 Conditions Originating in the perinatal period
 Congenital Malformations, deformations and
Chromosomal abnormalities
 Symptoms, signs and abnormal clinical and
laboratory findings not classified
 Injury, Poisoning

48. END
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