Introduction to PathologyIntroduction to PathologyByBy

Dr. Gehan Mohamed Dr. Abdelaty ShawkyDr. Gehan Mohamed Dr. Abdelaty Shawky

* Pathology: * Pathology: is the science which studies the

nature of the disease.

Pathology ClassificationPathology Classification

1.1. General pathology:General pathology:– The study of general reactions of cells and

tissues to insults and injuries that are basic to all disease processes.

2.2. Systemic pathology:Systemic pathology:– The study of specific disease processes or

reactions as they affect particular organs or organ systems e.g. CVS, CNS, GIT…..etc.

Applied pathology Applied pathology

1. Anatomic pathology:1. Anatomic pathology:a. Necropsy pathologyb. Surgical pathologyc. Cytopathology

2. Clinical pathology.2. Clinical pathology.3. Forensic pathology.3. Forensic pathology.

1.1. Anatomic Pathology:Anatomic Pathology:– Making diagnosis by examining tissues.

1.1. Necropsy pathology:Necropsy pathology:– Examination of tissues excised from cadavers in an

effort to establish the cause of death. – This is called “autopsy”.

2.2. Surgical pathology: Surgical pathology: – Examination of tissues excised from living patients in

an effort to establish a specific diagnosis.– This is called “biopsy”.

3.3. Cytopathology:Cytopathology:1.The microscpocic study of exfoliated cells within body

fluids.

2. Clinical pathology: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:3. Forensic pathology:

– Subspecialty dealing with medicolegal investigation

of death.

Biopsy 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 won’t 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.

Needle or core biopsy

Excisional biopsy

FNAC = Fine Needle Aspiration CytologyFNAC = 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)

FNAC

The Disease: The Disease:

The structural and functional changes in organs

and tissues due to exposure to an irritant

(causative agent of the disease).

* Classification of Diseases:A. Developmental: genetic, congenital.

B. Acquired:

1. Inflammatory .

2. Neoplastic e.g. Tumors

3. Degenerative e.g. Ageing.

4. Metabolic .

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

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.).

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.

MORPHOLOGY OF THE DISEASE

1.1. Gross (macroscopic) changes: Gross (macroscopic) changes: By naked eye

examination.

2.2. Histologic (microscopic) changes: Histologic (microscopic) changes: By light microscope

examination.

3.3. Ultrastructural changes: Ultrastructural changes: By an electron microscope

examination.

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

(2). Microscopic examination: (2). Microscopic examination: for tissue sections fixed in formalin then stained by H&E

(hematoxylin and eosin) to be examined by light microscope. Fatty liver

Hemangioma

Normal liver Fatty liver

Prognosis

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

death.

Welcome to PathologyWelcome to Pathology