Category Archives: Anatomic Pathology

Information and posts on surgical pathology, including pathology, pathogenesis, cancer, tumors, diseases, stains, histochemical stains, molecular techniques, molecular, diagnostic tests, immunohistochemistry, in situ hybridization and more.

Amyloidosis

Posted on August 25, 2011 by admin

Amyloidosis

CLASSIFICATION OF AMYLOIDOSIS
Clinicopathologic Category Associated Diseases Major Fibril Protein Chemically Related Precursor Protein
Systemic (Generalized) Amyloidosis
Immunocyte dyscrasias with amyloidosis (primary amyloidosis) Multiple myeloma and other monoclonal B-cell proliferations AL Immunoglobulin light chains, chiefly lambda type
Reactive systemic amyloidosis (secondary amyloidosis) Chronic inflammatory conditions AA SAA
Hemodialysis-associated amyloidosis Chronic renal failure Abeta2 m beta2 -microglobulin
Hereditary amyloidosis
Familial Mediterranean fever – AA SAA
Familial amyloidotic neuropathies (several types) – ATTR Transthyretin
Systemic senile amyloidosis – ATTR Transthyretin
Localized Amyloidosis
Senile cerebral Alzheimer disease Abeta APP
Endocrine
Medullary carcinoma of thyroid – A Cal Calcitonin
Islet of Langerhans Type II diabetes AIAPP Islet amyloid peptide
Isolated atrial amyloidosis – AANF Atrial natriuretic fact

 

AL  amyloid light chain

AA amyloid-associated

TTR Transthyretin

APP amyloid precursor protien

 

Ultrastructural features of amyloid

By electron microscopy, amyloid is seen to be made up largely of non branching fibrils of indefinite length and a diameter of approximately 7.5 to 10 nm. This electron microscopic structure is identical in all types of amyloidosis. X-ray crystallography and infrared spectroscopy demonstrate a characteristic cross beta-pleated sheet conformation. This conformation is seen regardless of the clinical setting or chemical composition and is responsible for the distinctive staining and birefringence of Congo red-stained amyloid. In addition to amyloid fibrils, other minor components are always present in amyloid. These include serum amyloid P component, proteoglycans, and highly sulfated glycosaminoglycans. These nonproteinaceous substances are presumably derived from the connective tissue in which amyloid is deposited.

 

Histochemical stains for Amyloidosis

1 – As noted earlier, the histologic diagnosis of amyloid is based almost entirely on its staining characteristics. The most commonly used staining technique employs the dye Congo red, which under ordinary light imparts a pink or red color to amyloid deposits. Under polarized light, the Congo red- stained amyloid shows a green birefringence. This reaction is shared by all forms of amyloid and is due to the cross-beta-pleated configuration of amyloid fibrils. Confirmation can be obtained by electron microscopy.

2 – Potassium permanganate pretreatment of sections , has been used to distinguish amyloid type AA (sensitive to effect of pretreatment) from non-type AA amyloids (resistant) .The underlying mechanism is unknown .Recently , however , the specificity of potassium permanganate for this differentiation has been called into question. Both thioflavin T and S have been used for the demonstration of amyloid. Although these dyes have high levels of sensitivity , their specificity is less than that of Congo Red.

References:

1. Robbins & Cotran Pathologic Basis of Disease, 8th edition. Vinay Kumar, MBBS, MD, FRCPath; Abul K. Abbas, MBBS; Nelson Fausto, MD; Jon Aster, MD. Saunders. Published June 2009.

2. Sternberg’s Diagnostic Surgical Pathology, 5th edition. Darryl Carter, Joel K. Greenson, Victor E. Reuter , Mark H. Stoler. Lippincott Williams & Wilkins. Published Aug 26 2009.

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Autopsy Procedure

Posted on May 8, 2011 by admin

Autopsy Procedure

How to approach an autopsy?

I. Before the autopsy
1. Read warrant or consent
2. Note restrictions
3. Talk to people:
- talk to treating physician, if necessary
- talk to Coroner
- talk to police – investigating officer, identification officer

Review evidence: photos, videos of the scene, weapon, vehicle

4. Review charts

5. Consider differential diagnosis of manner – suicide, homicide, accidental, natural
- Is Forensic Pathologist needed?

6. Consider who should be present at the autopsy

II. Planning the autopsy
1. Special investigations:
Special procedures – carotids, vertebrals, cord, dry neck, SDH
Samples – DNA (muscle/bone/blood), Toxicology (liver/lung/blood/urine), Cultures
Consider x-rays – trauma, ballistics, stents

III. Performing the autopsy

1.  Identification and collection of evidence
- Visual (tattoo, scar)
- Dental
- Radiology
- Fingerprints
- DNA

2.  External examination – consider photography and examine for rigor, livor, decomposition, trauma, violence, drug use,

3.  Collection of trace evidence:
- swabs from anus, penis, vagina, mouth
- any stains on body (esp. genitalia)
- hair samples (pulled from scalp, pubis)
- fingernails
- use alternate light source (see semen, blood stains)

4. Internal examination
- examination of organs
- collect tissues
- special studies: (B5, electron microscopy, gram stain, cultures)

5. Summarize provisional report and contact Coroner

6. Review slides and other studies, issue final report

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Quality Assurance

Posted on March 12, 2011 by admin

Quality Assurance

Different types of error can occur in the laboratory:

Pre-analytical

1. Sampling error
2. Accessioning (sample mix-up, incorrect no, incorrect label, illegible label)

Analytical

1. Technologist error
2. Pathologist error

Post-analytical

1. Interpretation error (pathologist)
2. Clerical error (Incorrect patient entered)

Total quality management

Elements of your quality program:

-quality control
-quality indicators
-quality assurance
-quality management system
Designed to support efficient, effective, high quality and appropriate lab services (accurate and precise results, appropriate test selection, timely reporting, clinical usefulness)

A management system is designed to meet quality objectives

LIS System Important Aspects:

1.     Discuss within the department what features are need in a LIS.
a.    Essential requirements (egs. windows interface, voice recognition)
b.    Optional (eg. image capture, macros)
2.    Speak to several vendors.  Become aware of the differences and similarities between each system
3.    Visit pathology labs which use these systems, and ask about concerns, problems and suggestions.
4.    Consider system maintenance.  How available is the support system for problems that might occur
5.    How reliable is the company? How long have they been around for?

Quality control components of a laboratory

“Systems designed to ensure that results produced meet or exceed customer expectations”
1.    Equipment:
a.    Temperature (refridgerator, water bath, processors)
b.    Regular maintenance
2.    Reagents:
a.    Expiry dates
3.    Controls
a.    Histology: H&E slide every morning
b.    Immunohistochemistry: Positive and negative controls with every slide

4.    Random slide review (customer satisfaction survey):
a.    Label quality
b.    Coverslip (position, air bubbles)
c.    Section quality (thickness, knife marks, cut deep enough into block)
d.    Pickups
e.    Stain quality (hematoxylin, eosin, counterstain, special stains, IHC: proper signal, low noise, staining artifacts)

Measuring quality indicators for cytology.

Elements to include for professional quality assurance and how monitor them.

Cytology
1.    TAT (turn around time)
2.    Overdue case tracking (so cases don’t get lost)
3.    Cyto-histology correlation

-review all discordant cases monthly, pull previous cyto and histo over the last year & match to body site to determine:

a)    Sampling error
b)    Screening error
→ tech:    higher rate w/individual tech? (false negatives-didn’t dot it)
c)    Interpretation error
→pathologist

4.    Measure different types of rates
a)    “unsatisfactory slide” rate → provide feedback to clinician

Gynecology Cytology

All of the above plus:
1.    Rescreening 10% of negatives directed/targeted rescreen of specific diagnoses
2.    All HSILs must be reviewed and rescreened by techs
3.    New HSIL, 3yr. backscreen on all previous paps
4.    Measure different types of rates
a.    ASCUS:SIL rate → should be less than 2%
b.    ASCUS:Total cases → should be around 3-5%
c.    “unsatisfactory slide” rate → provide feedback to clinician

OLA standards:

Instructions (how to collect specimen) → Reqs with clin, pap, LMP hx → accepted staining practice → contamination prevention → separate screening area → all paps screened by techs → abnormal areas marked and tech comments kept → techs can only sign out benign or negative →← Pathologist provides feedback to techs

Autopsy Quality Assurance

1.    TAT
2.    Case rounds (autopsy conference, mortality and morbidity rounds, ML rounds)
3.    Provincial centralized forensic case review
OLA requirements:
-consent, identification, paperwork
-block and slide retention (20yrs adult, 50yrs child)
-report to include gross, micro, major findings and info to determine cause of death
-wet tissue retention (KGH 2yrs.)

Surgical Pathology Quality Assurance

1.  TAT
2.  Overdue case tracking (so cases don’t get lost)
3.  Correlations
a.  frozen section and permanents
b.  addendum/amended and original dx
c.  second review on 5-10%
d.  case rounds/tumor board review rate
4.  Good lab practices
a.  incident reporting
b.  daily staining QA log
c.  customer satisfaction surveys
5. OLA standards

Frozen Section Quality Assurance

-manual covers specific specimen types
-results communicated directly and recorded
-can audit times

Immunohistochemistry Quality Assurance

-appropriate controls
-IHC slides kept with other case slides
-document IHC slide results

Quality Assurance Reporting

-Gender, DOB, unique ID, attending and submitting docs
-Clin history
-Gross
-FS dx
-Micro
-Final
-Pathologist signature

Storage times

-wet tissue = 4+ wks. after report issued
-blocks and reports= 20yrs adults; 50yrs children
-slides= 10yrs adults, 10yrs. after 18th birthday children

Maintaining Quality Assurance

1.    Lab overall
a.    Certification
b.    Compentency
2.    Specimen quality
a.    labelled with 2 unique IDs
b.    broken
3.    Stain quality
a.    expiry date
b.    filtered
c.    check quality of stain microscopically
4.    Tech competency
a.    experience
b.    volume
5.    Cyto-Histo correlation component
6.    Report-double check
7.    External QA program
8.    Rounds
a.    Intra-departmental
i.    teaching
ii.    feeback to techs
b.    Inter-departmental rounds
i.    tumor board rounds
c.    Extra-deparmental rounds
i.    peripheral hospitals affiliated with regional hospital
9.    Satisfaction survey

Continuous Quality Improvement

A systematic method of continously improving quality.

1.    identify problem
2.    collect data
3.    develop hypothesis
4.    create intervention
5.    measure the improvement
6.    adopt the new process
7.    REPEAT

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Pathology

Posted on June 8, 2010 by admin

What is Pathology?

Pathology is the study of disease. Pathology mostly concentrates on the morphology of disease both at the microscopy level and at the naked eye level. Rudolph Virchow is the father of pathology. Virchow discovered that disease is a cellular process and that disease may be studied by observing the morphology and changes of morphology of cells.

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