01 Introduction to Pathology

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Introduction to

PathologyLourdes T. M. Dominguez, MD, DPSPFaculty of PharmacyUniversity of Santo Tomas


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Definition of Terms

Pathology

Greekpathos = pain and logos = study

Also calledpathobiology

It is a form of science and a branch of medicine

that involves testing samples and diagnosing

physical health problems from their evidence.


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Definition of Terms

Pathology

Study of the nature, causes, processes,

development, consequences of disease and the

modifications in cellular function and changes incellular structure produced in any cell, organ, or

part of the body by disease.

Pathology addresses 4 components of disease:

1. Cause/etiology2. Mechanisms of development (pathogenesis)

3. Structural alterations of cells (morphologic changes)

4. Consequences of changes (clinical manifestations)


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Definition of Terms

**The microscope is an

important factor in detecting

tissue changes, especially in

the examination of small

sections of tissue removed for

diagnosis; for this reason real

progress in pathology was not

made until the 19th century.


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Pathogenesis The development of a diseased or morbid

condition.

Pathologist A physician who interprets and diagnoses the

changes cause by disease in the body.

A physician who interprets and diagnoses thechanges cause by disease in the body.

Definition of Terms


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Pathologist A specialist physician expert in the origin and

development of disease and the microscopicanalysis of body tissues.

A doctor who studies all aspects of disease withan emphasis on the nature, causes, anddevelopment of abnormal conditions, as well asthe structural and functional changes that result

from disease processes. The laboratory expert behind the front-line clinical

team.

Definition of Terms


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Medical Technologist

An Allied Health Professional who performs

diagnostic analysis on human blood, urine, and

body fluids such as cerebral spinal fluid,peritoneal, pericardial, and synovial, as well as

other specimens such as stool and sputum.

Definition of Terms


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Autopsy

In Greek, a seeing for oneself: auto-, auto- +

opsis, sight

Also called necropsy,postmortem examination. Systematic examination of a cadaver for study or

for determining the cause of death.

Uses many methodical procedures to determine

the etiology and pathogenesis of diseases, forepidemiologic purposes, for establishment of

genetic causes, for family counsel, and for

improvement of safety standards for the living.

Definition of Terms


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Biopsy

Examination of cells or tissues from a living organism.

Excised material may be studied in order to

diagnose disease or to confirm findings ofnormality.

Incisions may be made and total or partial lesions

removed in the form of wedges or cylindrical

pieces, or scrapings of the surface membranes of

internal organs may be collected.

Tumors are routinely biopsied in order to

determine whether they are benign or malignant.

Definition of Terms


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I. Gross Pathology & Microscopic

Pathology

II. Anatomic Pathology

III. Clinical Pathology

Divisions of Pathology


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I. Gross Pathology & MicroscopicPathology

Gross Pathology

The recognition of disease based on macroscopic

examination of surgical specimens generated at

the time of surgery or at autopsy.

Microscopic Pathology

The recognition of disease based on microscopicexamination of surgical specimens generated at

the time of surgery or at autopsy.


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Anatomic Pathology

The study of changes in the function, structure, or

appearance of organs or tissues, including

postmortem examinations and the study of biopsy

specimens.

Sections:

A. Surgical Pathology

B.A

utopsy PathologyC. Exfoliative Cytology



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A. Surgical Pathology

The pathology of disease processes that are

surgically accessible for diagnosis or treatment.

The study of gross appearance and histology oftissues removed during surgery.



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B.Autopsy Pathology

It involves the external and internal examination

of a human body after death.

The study of gross appearance and histology oftissues removedfollowing death.

The most important task is to identify the cause of

death.



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C. Exfoliative Cytology

Also known as cytopathology

The study of desquamated cells from a body

surface or lesion to detect malignancy. Cells are collected from lesions, sputum, urine,

secretions or any body fluid accumulation.

The cells may be collected through aspiration,

brushing, washing, smear and scraping.



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Clinical Pathology

The branch of general pathology directed to the

diagnosis and monitoring of diseases through the

examination of blood, body fluids, secretions, and

tissue biopsy specimens for chemical,

morphological, microbiological, and

immunological abnormalities.



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Identifies and interprets changes that characterizedifferent diseases or disease states in cells,

tissues, and fluids of the body

Monitor the metabolic status of patients under

medical therapy

Decipher specific markers that characterize

individual patients for purposes such as

transfusion or transplantation



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A. Clinical Chemistry (incl. Toxicology)B. Hematology

C. Clinical Microscopy

D. Blood Banking (incl. Transfusion Medicine)

E. MicrobiologyF. Clinical Immunology & Serology



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A.ClinicalChemistry (incl. Toxicology)

Division of clinical pathology involving

biochemical analysis performed on human

samples (blood, fluids, tissues) outside the body

(in vitro).

Substances which could be assayed include sugars,

lipids, proteins, antibodies, enzymes, hormones,

vitamins, metals, electrolytes.



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Methods employed are spectrophotometry,

fluorometry, enzyme kinetics, enzyme

immunoassay (EIA), electrophoresis, flame

photometry, ion selective electrodes, HPLC, gaschromatography, mass spectrometry, and atomic

absorption spectrometry.

Most instruments are however almost completely

automated.



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In the toxicology subsection, the blood, urine, and

other body fluids are analyzed for the presence of

drugs and substances of abuse.

An equally important application of toxicology

testing is to measure the blood levels of

therapeutic drugs to assure that concentrations

are adequate to treat the disease but not so high

as to cause toxic side effects.



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B. Hematology

Involves assessment of the cellular elements (red

blood cells, white blood cells, and platelets) in

blood samples.

The blood cells may be enumerated, either by

manual cell-counting techniques or by automated

particle-sensing and particle-sizing instruments.



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B. Hematology

Microscopic observation of stained peripheral

blood smear is limited to assessing the

morphology of atypical cells as they may appear in

cases of dysplastic syndromes and overt

leukemias.



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B. Hematology

Pathologists specialized in this field i.e.

hematopathologists also examine bone marrow

and lymph node biopsies. They are expert in the

field of anemia, leukemia and lymphomas.

In complicated cases where the diagnosis of a

hematological disorder cannot be made by study

of the peripheral blood smear, a bone marrow

examination may be necessary.



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C.ClinicalMicroscopy Deals with the processing and analysis of body

fluids such as urine, stool, CSF etc.

The laboratory identification of parasitesinvolves detecting microscopically the typicalforms in body fluids and secretions



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D.BloodBanking (incl. TransfusionMedicine)

Also called Immunohematology

Deals with collection, storage, compatibility andsafety of blood and its various components for thepurpose of human transfusion.



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Specific tasks include:

1. Blood collection after donor screening

2. Chemical and serologic tests to excludetransmission of infective diseases

3. Component preparation and proper storage

4. Blood typing, screening for antibodies againstred cells and compatibility testing

5. Immunophenotyping of blood cells

6. Investigation into transfusion reactions



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Specific tasks include:

7. Apheresis & Plasmapheresis

A procedure where plasma or platelets can beseparated from the withdrawn blood and theformed elements (red cells and platelets).



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E.Microbiology A division of clinical pathology involved in

isolation, culture, and identification, of micro-organisms (parasites, fungi, bacteria & viruses) in

biological samples.

In addition to conventional microscopic andbiochemical methods for identification, DNA/RNA

based assays (including PCR) and immunoassaysare increasingly being used.



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E.Microbiology

Subdivisions include bacteriology, parasitology,

mycology (fungi) and virology.

Presumptive identification of microbes can be

made by microscopically examining direct mounts

of an appropriate portion of the specimen or thin

smears that have been stained with one of a

variety of dyes.

Rapid presumptive diagnoses can also be made by

directly testing specimens with a variety of

immunological reagents.



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E.Microbiology

Specimens are applied to the surface of a variety

of agar culture media for the purpose of

recovering in pure culture any bacterial speciesthat may be clinically significant.

Gram stains may determine the cellular

morphology and staining characteristics of the

bacteria, and a variety of rapid, direct tests can beperformed to provide an early identification.



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E.Microbiology

Bacterial identifications and antibiotic

susceptibility tests may be performed in a variety

of packaged systems.



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E.Microbiology

The laboratory identification of fungi and the

diagnosis of fungal infections is similar to that

described for the bacteria.

Specimens are inoculated on special fungal media,

the plates are incubated for periods as long as 4

weeks, and the growth of any mold or yeast is

identified morphologically and biochemically.

Nucleic acid probes are available to quickly

confirm any fungus colony suspected of being one

of the dangerous pathogens



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E.Microbiology

Viruses can live only in viable cells and, for the

most part, can survive briefly outside human or

animal hosts.

Culture techniques must use embryonated eggs,

cell culture suspensions, thin cell sheets called

monolayers, or laboratory animals.

Species of viruses are identified by observing their

ability to produce certain cytopathic effects in the

cells where they are growing or to cause

recognizable diseases in laboratory animals.



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F.ClinicalImmunology and Serology

The discipline in which infectious diseases are

diagnosed by detecting antibodies in serum and

other body fluids.

In practice, immunologic and serologic techniques

are used to diagnose an infectious disease when

the agent may be too difficult to recover in

culture.



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The Medical Technologist's Role inthe Healthcare Process

A Medical Technologist's role in the healthcare

process is to provide accurate results in a timely

manner.

These results will ultimately be used to help makea diagnosis or monitor treatment.


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Observe details of cells, ova and cysts of parasiticinfections.

Test whether the blood of the donor is

compatible with the blood of patient-recipient.

Utilize special stains to identify microorganisms.

Measure substances in blood and other bodysubstance


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Reagent preparation

Collect specimen for study

Preparation of specimen

Quality control

Water testing


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End of Presentation

01 Introduction to Pathology

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