Transcript INTRODUCTION TO CLINICAL PATHOLOGY - V4US-33rd

CLINICAL PATHOLOGY
BY:
DR (MRS) B.J.THANENTRHIRAN(MBBS)

Pathology is the study (logos) of suffering (pathos).

Pathology address following components of disease.
1.
Cause / Etiology
2.
Incidences
3.
Mechanisms of development (pathogenesis)
4.
Structural alterations of cells (morphologic changes)
5.
Consequences of changes (clinical manifestations)
Pathology
Anatomic pathology
Clinical pathology

Anatomic pathology is concerned with the diagnosis
of disease based on the gross, microscopic, chemical,
immunologic and molecular examination of organs,
tissues, and whole bodies (autopsy).

Clinical pathology is concerned with the diagnosis of
disease based on the laboratory analysis of



body fluids
and tissues
using the tools of




Chemistry
Microbiology
Hematology
and Molecular pathology
Subsections

Anatomic pathology




Cytopathology
Histopathology
Surgical pathology
Clinical pathology






Hematology
Chemical pathology
Microbiology
Immunology
Urinalysis
Blood bank

Cytopathology is a branch of pathology that studies and
diagnoses diseases on the cellular level.

Histopathology refers to the microscopic examination of
tissue in order to study the manifestations of disease.

Surgical pathology involves the gross and microscopic
examination of surgical specimens and biopsies.
Cytopathology / cytology
Cell collection

Exfoliative cytology



Cells from spontaneous exfoliation
Cells from mechanical exfoliation(scraping/brushing)
Intervention cytology

Intervening into the body for sample collection

FNAC – Fine Needle Aspiration Cytology
Indications for cytopathology
1.
Diagnosis of malignancy and its type
2.
Diagnosis of premalignant diseases
3.
Detection of inflammation and certain types of
pathogenic agents
4.
Study of the hormonal patterns and evaluation of the
gonadal hormonal activity.
5.
Follow-up and monitoring
chemotherapy and irradiation.
of
response
6.
The identification of sex chromosome. (Barr bodies)
7.
Tumor markers study on cytological specimens
to

Following parameters are seen in the cellular sampling




Nucleus
Nucleolus
cytoplasm
In addition following pathologies can be seen.






Microbial infections
Reactive changes
Immune reactions
Cell aging
Amyloidosis
Autoimmune diseases
Cytology specimens
1.
Fluids
2.
Effusion into body cavities (pleural, peritoneal, pericardial)
3.
Cyst aspirates
4.
CSF
5.
Urine
6.
Sputum
7.
Wash specimens – bronchial, bladder
8.
Brush cytology – bronchial, cervical, gastro intestinal.
9.
Pap smears
10.
Bone marrow aspiration
11.
Fine needle aspiration.
Advantages of cytology

Provides a rapid, inexpensive & simple diagnosis.

Little tissue injury.


Frequent sampling
Evaluation of progression to treatment / recurrence

Better accepted by the patient & clinician

Sample cells from wider surface than a biopsy

Cells can be obtained by inaccessible / difficult to access
areas

Determination of hormonal states

Minimum distortion of cells

Smears permit better evaluation of the nature of
inflammations and infections.
Limitations of cytology

Cytologic diagnosis is not always final. Must be confirmed
by histology.

Diagnosis is based upon the study of minute cellular
details.



Tissue pattern cannot be appreciated
Interrelation & arrangement of the cells to the supporting
stroma cannot be established.
Location of lesion cannot be pin pointed (except in
FNAC)

Size of the lesion cannot be estimated.

Error / misinterpretation may occur.
Fine Needle Aspiration Cytology (FNAC)

Used to investigate superficial lumps or masses.

Lung, intra-abdominal and retroperitoneal samples can be
taken with the help of radiologic imaging (CT, ultrasound)

Sampling is done for diagnostic purposes and to asses
the effect of treatment.
Advantages of FNAC

Easy, reliable, cost effective

Out patient procedure

Minor surgical procedure, No risk of anesthesia

Safer than open surgical biopsies

Easily repeatable

Less complications

Patient can go back to normal activities soon

Can get results rapidly
Disadvantages of FNAC

False negative results (some lesion do not exfoliate cells
well, needle may miss the site of the lesion, timid
collection, inadequate negative pressure).

Definitive diagnosis is difficult.
Complications of FNAC




Needle trauma
Needle track seeding - testicular tm, chondrosar
Hematoma
Pain
Preparations before the procedure

No use of aspirin or non-steroidal anti-inflammatory
medications (e.g. ibuprofen, naproxen) for one week
before the procedure

No food intake a few hours before the procedure

Routine blood tests (including clotting profile) must be
completed two weeks before the biopsy

Suspension of blood anticoagulant medications

Antibiotic prophylaxis may be instituted.

Check vital signs before the procedure

IV line if necessary.
Equipments needed for FNAC procedure
Syringes
1.


Standard disposable plastic syringes of 10ml are used.
Syringe should be of good quality and should produce good
negative pressure.
Needles
2.

Standard disposable 22-24 gauge 1-1½-inch needles are
used for plain FNAC.
Slides
3.


Fixatives
4.




5.
Plain glass slides of good quality are used. Slides should be
clean, dry, transparent and grease free.
An important procedure is slide labeling at the time of
sampling.
These are applied to the smears as a spray or by immersion
of the slide into a liquid.
The most commonly used is 95 % Ethanol.
This inexpensive readily available liquid provides excellent
cytological details.
Fixative is kept ready in Coplin jars.
Container
Other supplies
6.

Test tubes, pencil for marking, alcohol, swabs for skin, watch
glass, saline, adhesive dressing, gloves etc. are needed.

All the materials required are assembled in advance
before starting the procedure.

This is extremely important as delay in fixation can
make interpretation of smears difficult.
Steps to be followed before performing the
aspiration
1.
Relevant history and clinical details, radiological
findings, provisional diagnosis etc. must be entered in
the requisition form. Site of FNA must be clearly
stated.
2.
Lesion to be aspirated is palpated and its suitability for
aspiration assessed. The appropriate needle is selected
accordingly.
3.
The procedure must be clearly explained to the patient
and consent and co-operation ensured. Patient may be
anxious which needs to be allayed. Ignoring this simple
but crucial step can result in failure.
4.
Before starting the procedure, ensure that all the
required equipment, instruments and supplies are
available.
5.
All universal precautions should be followed during the
procedure.
Steps to be followed during the aspiration

Position the patient.

Sterilize the skin above the area to be biopsied with
antiseptics.

May use local anesthesia but often not necessary.

Locating the mass by palpation by non dominant hand.

Aspirates should be obtained using preferably a 23 gauge,
1 ½ inch disposable needle mounted on a 10 ml plastic
syringe, held by the dominant hand.

The needle should be gently introduced through the skin
passing to the level of the dominant mass.

Having confirmed the position of the needle within the
mass, negative pressure should be created within the
syringe by pulling back the plunger.

The needle should move back and forth through the
mass, in different rotational directions.

Suction should be maintained throughout the process by
outward.

All suction should be released before removing the
needle from the mass.

Then the needle should be withdrawn gently from the
mass.

To limit hematoma formation from the site of the
puncture, firm pressure should be applied with a piece of
cotton for two minutes.
Preservation and processing of Smears

Smears are prepared and fixed according to the requirements
of the stain to be used.
1.
Air-drying followed by hematological stains.
2.
Alcohol fixation followed by Papanicolaou (pap) or
hematoxylin and eosin (H&E) staining.
Preparation and fixation for pap/ H&E staining

Immediately after withdrawing, detach the needle, draw air
into the syringe, reattach the needle and express the material
in the needle onto a slide.

Needle tip is brought into light contact with the slide and the
aspirate is carefully expressed without spraying into the air,
which can cause air-drying and also can form aerosols, which
are potentially infectious.

Aspirates are smeared immediately using another slide or
cover slip or with the needle itself and dropped into the
fixative.

The cells must be delicately and thinly smeared with minimal
distortion and fixed according to the stain to be used.

Spreading the cells too thinly as well as preparing too many
smears is an error because of cellular distortion or dilution.
Thus the smears must be of adequate thickness.

Unsatisfactory smears can be due to non representative /
inadequate samples or due to poor quality of preparation
(thick smears, extreme admixture with blood, delayed
fixation, over staining etc)
Quality control Measures

In addition to details of technique (procedure, preparation,
quality of materials used) and clinical correlation; other routine
quality control practices regarding specimen reception
(checking patient details, identification of slides, number of
slides from each patient, labeling the slides), preparation and
maintenance of stains, staining procedure, mounting, record
keeping etc. are needed for optimal quality of diagnosis.