INTRODUCTION TO CLINICAL PATHOLOGY - V4US-33rd
Transcript INTRODUCTION TO CLINICAL PATHOLOGY - V4US-33rd
DR (MRS) B.J.THANENTRHIRAN(MBBS)
Pathology is the study (logos) of suffering (pathos).
Pathology address following components of disease.
Cause / Etiology
Mechanisms of development (pathogenesis)
Structural alterations of cells (morphologic changes)
Consequences of changes (clinical manifestations)
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
using the tools of
and Molecular pathology
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
Cells from spontaneous exfoliation
Cells from mechanical exfoliation(scraping/brushing)
Intervening into the body for sample collection
FNAC – Fine Needle Aspiration Cytology
Indications for cytopathology
Diagnosis of malignancy and its type
Diagnosis of premalignant diseases
Detection of inflammation and certain types of
Study of the hormonal patterns and evaluation of the
gonadal hormonal activity.
Follow-up and monitoring
chemotherapy and irradiation.
The identification of sex chromosome. (Barr bodies)
Tumor markers study on cytological specimens
Following parameters are seen in the cellular sampling
In addition following pathologies can be seen.
Effusion into body cavities (pleural, peritoneal, pericardial)
Wash specimens – bronchial, bladder
Brush cytology – bronchial, cervical, gastro intestinal.
Bone marrow aspiration
Fine needle aspiration.
Advantages of cytology
Provides a rapid, inexpensive & simple diagnosis.
Little tissue injury.
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
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
Diagnosis is based upon the study of minute cellular
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
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
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 track seeding - testicular tm, chondrosar
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
Standard disposable plastic syringes of 10ml are used.
Syringe should be of good quality and should produce good
Standard disposable 22-24 gauge 1-1½-inch needles are
used for plain FNAC.
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
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
Fixative is kept ready in Coplin jars.
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
Relevant history and clinical details, radiological
findings, provisional diagnosis etc. must be entered in
the requisition form. Site of FNA must be clearly
Lesion to be aspirated is palpated and its suitability for
aspiration assessed. The appropriate needle is selected
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.
Before starting the procedure, ensure that all the
required equipment, instruments and supplies are
All universal precautions should be followed during the
Steps to be followed during the aspiration
Position the patient.
Sterilize the skin above the area to be biopsied with
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
All suction should be released before removing the
needle from the mass.
Then the needle should be withdrawn gently from the
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.
Air-drying followed by hematological stains.
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
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.