Pathology Flashcards
how does anatomic pathology relate to laboratory medicine?
lab medicine = general pathology (ANATOMIC pathology + clinical pathology)
what is included in anatomic pathology? (4)
- autopsy pathology
- surgical pathology
- cytopathology
- speciality labs (immunohistochemistry, immunofluorescence, electron microscopy)
what is included in clinical pathology? (3)
- clinical biochemistry
- microbiology
- laboratory hematology
what is surgical pathology?
any tissue removed or biopsied at surgery or radiology gets sent to pathology
what are the surgical procedures in surgical pathology? (5)
- core (needle) biopsies (remove long narrow piece)
- incisional biopsies (large mass)
- excisional biopsies (lymph node)
- resection
- exenteration (entire content)
explain a pathologist’s OR consultation
- can be macroscopic or microscopic examinations
- if light microscopy required: freeze tissue cut on cryostat and stain with H&E
what are the advantages and drawbacks to pathologist OR consultations?
advantage: fast (takes 5-15min)
disadvantage: since freezing, cannot use for all specimens and is small diagnostic error rate
what changes in the procedure of small vs large pieces in macroscopy?
small pieces are fixed directly to prevent degradation
large pieces have sample representative sections
what are the steps of biopsies? how long does each step take?
- fixation (min. few hrs, often 24-48hr)
(STEPS 2-4 OVERNIGHT) - dehydration
- clearing
- infiltration by wax
(STEPS 5-6 TAKES A FEW HOURS) - embedding
- cutting
(STEPS 7-8 AUTOMATED) - staining
- distribution to pathologist
what fixation agent is used?
10% formalin in water
what is the fixation step?
- fixation (min. few hrs, often 24-48hr)
(STEPS 2-4 OVERNIGHT) - dehydration
- clearing
- infiltration by wax
(STEPS 5-6 TAKES A FEW HOURS) - embedding
- cutting
(STEPS 7-8 AUTOMATED) - staining
- distribution to pathologist
preserves (fixes) structures by cross linking proteins (NH2 groups), inactivating proteolytic enzymes
the (slower/faster) the tissue is fixed, the better
faster
explain steps 2-4:
- fixation (min. few hrs, often 24-48hr)
(STEPS 2-4 OVERNIGHT) - dehydration
- clearing
- infiltration by wax
(STEPS 5-6 TAKES A FEW HOURS) - embedding
- cutting
(STEPS 7-8 AUTOMATED) - staining
- distribution to pathologist
step 2: dehydration with graded alcohols
step 3: use xylene (organic solvent) miscible to clear it
step 4: infiltrate with paraffin wax
explain steps 5-6:
- fixation (min. few hrs, often 24-48hr)
(STEPS 2-4 OVERNIGHT) - dehydration
- clearing
- infiltration by wax
(STEPS 5-6 TAKES A FEW HOURS) - embedding
- cutting
(STEPS 7-8 AUTOMATED) - staining
- distribution to pathologist
step 5: place tissue in the correct orientation and mold with paraffin, cassette and let harden
step 6: cut sections on microtome at thickness of 3-5um for light microscopy and put on glass slide
explain step 7:
- fixation (min. few hrs, often 24-48hr)
(STEPS 2-4 OVERNIGHT) - dehydration
- clearing
- infiltration by wax
(STEPS 5-6 TAKES A FEW HOURS) - embedding
- cutting
(STEPS 7-8 AUTOMATED) - staining
- distribution to pathologist
use routine hematoxylin and eosin OR other special stains
- since hematoxylin is aqueous, remove wax: remove wax (heat, xylene) -> dehydration (alcohol) -> water -> stain with hematoxylin
- differentiate (destaining) using weak alcohol
- apply eosin
- dehydrate (alcohol) -> clear (xylene)
- mounting medium, coverslip
what stains are simple acid base reactions?
hematoxylin and eosin
describe hematoxylin (color, what, where)
- blue/purple
- basic (binds to basophilic substances like ACIDS, NUCLEIC ACIDS)
- in the nucleus
describe eosin (color, what, where)
- red/pink
- acidic (binds to acidophilic substances like BASIC proteins)
- in the cytoplasm
sometimes, eosin needs to be used for more intense staining. in what two cases does this happen?
necrosis and apoptosis
what is masson trichrome used for?
- collagen and fibrosis
what color are the following stained with masson trichrome:
- collagen
- nuclei
- muscle
- cytoplasm
- blue
- dark blue
- red
- light red/pink
what is the Prussian blue stain for? what color does it stain?
- for iron
- stains blue
what is ziehl-neelsen used for?
acid fast bacilli
what is grocott used for?
fungal organisms
place the correct term with the stain type (hematoxylin or eosin):
- nuclear staining
- cytoplasmic staining
- hematoxylin
- eosin
how is nuclear staining used to make a diagnosis? (3)
- reflects DNA (genetic material)
- regulator of proliferation and metabolic activities
- susceptible to mutations
how is cytoplasmic staining used to make a diagnosis (2)
- reflects effort proteins (i.e., enzymes)
- reflects phenotype of the cell
how does immunohistochemistry work?
use of antibodies to check for certain antigens (markers) in a sample of tissue
what are the steps to immunohistochemistry?
- inject protein to generate the specific AB
- apply AB to histologic sections along with chromogen to detect it
- look for presence/absence of AG, intensity and location
what are CD molecules in immunohistochemistry?
cluster of differentiation number assigned to group/cluser of ABs that recognize a specific cell surface molecule
what type of immunohistochemistry can be used as predictive factor?
CD molecules: if cell X is stained with ab against Y, it predicts a response to anti-Y
what can immunohistochemistry stain for? (4)
- cell surface proteins
- cytoplasmic proteins
- nuclear proteins
- infectious agents
how does immunofluorescence compare to immunohistochemistry?
also uses AG and AB but stained with fluorescein-labeled AB and examined with UV microscopes
what do we use electron microscopy for in pathology? (2)
- used for very high resolution
- diagnostic for renal glomerular diseases and virology
T/F: to get the ultra thin sections needed for electron microscopy, we cut them the same way as regular biopsies
FALSE: embed them in epoxy resin and cut on diamond knifes
what is cytopathology and what are its 2 sections?
looks at whole cells (individual or sheets) rather than sections of tissues
- gynecologic (PAP smears)
- non-gynecologic (fine needle aspirates, exfoliative)
how is the procedure for cytopathology different/similar to surgical pathology?
difference:
- uses smears and cytocentrifuge
- does not use immunohistochemistry/fluorescence UNLESS in cell blocks
similar:
- if there’s enough tissue, make cell blocks that are processed the same as surgical pathology
what is a syndrome?
Set of symptoms (history) and/or signs (physical examination) that occur together
what is pathology and how is it divided?
- scientific study of diseases from molecules to patients
- general pathology and organ-based pathology (systemic)
what is the current concept and practical application of pathology?
- Diagnosis of diseases
- Determination of prognostic and predictive factors
how do we classify diseases?
systematic arrangement of diseases in categories according to criteria or common features
describe the epidemiology and predisposing/risk factors approach to disease (4)
- Incidence and prevalence
- Age, gender, racial differences
- Geographic/global distribution and epidemics
- Relation to occupational, environmental, social aspects
describe the etiological/cause approach to disease (2)
- Known: Genetic vs acquired vs multifactorial
- Unknown: Idiopathic
describe the pathologenesis (HOW) approach to disease (2)
- Mechanism where the etiological agent results in the pathological alteration of the disease
- Once you have this, you have targetable intervention for therapy
where can we see pathological alterations (5)?
- Macroscopic (gross)
- Light microscopic
- Histochemical (special stains) and immunohistochemical stains
- Ultrastructural (electron microscopy)
- Molecular
describe the pathophysiology and effects approach to disease (2)
- functional consequences of the pathologic/structural alterations
- Levels –> cells/molecules, organs, patient
describe the clinical manifestations approach to disease (3)
- Symptoms via history
- Signs via physical examination
- Imaging and laboratory data
describe the diagnosis approach to disease (4)
- History and physical exam
- Imaging, lab data
- Pathological examination (macro and micro)
- Need to think about differential diagnosis
describe the complications approach to disease (2)
- Events that aren’t related to signs/symptoms of the disease
- Certain overlap with side-effects
what are prognostic factors?
- things affecting patient outcome and survival
- i.e., performance status, severity, histological type of lesion, etc.
what are predictive factors?
- predict potential response to specific therapies
- i.e., molecule that predicts the response of a drug
explain the pathway from ethology to outcome
- predisposing factors affect etiology
- pathogenesis and predisposing factors affect how etiology leads to pathological alterations
- mild pathological alterations lead to asymptomatic symptoms while severe alterations lead to clinical manifestations (affected by pathophysiology)
- to catch early diagnoses, want to screen for asymptomatic symptoms, but if you have clinical manifestations, you can just diagnose it
- once a diagnosis is reached, we can apply therapy (which is affected by predictive factors)
- prognostic factors will affect the outcome
