intro to vet diagnostic laboratories Flashcards
lesion
a pathologic change in a tissue/cell
cause/etiology
casuative agen
pathogenesis
sequence of events that lead to or underlie a disease
prognosis
prediction of outcome of the pathologic process
diagnosis
a concise statement of the nature, cause of name of a disease
what is a biopsy
removal and examination of tussue from a live patient
why do a biopsy
- make or confirm a diagnosis
- rule out other diseases
- determine adequacy of excision
- provide prognostic information
- guide therapeutic decisions
the tissue is examined out of context, so interpretation relies:
on the clinical data you provide
what should a submission form always include
- decription of lesion
- location sampled
- number of containers/specimens
- signalment of patient
- history/clinical data pertinent to case
- specific questions to be answered
what are the most common types of biopsies
- endoscopic (pinch)
- needle core (Tru-Cut)
- punch
- incisional
- excisional
what is an endoscopic biopsy
- small superficial tissue samples obtained thorugh and endoscope
- usually respiratory, alimentary, or urogenital mucosa
- multiple samples increase likelihood of a diagnosis
what is a needle core biopsy
- long thin cylinders of tissue often obtained w/ ultrasound guidance
- solid/parenchymatous tissues
- multiple samples
what is a punch biopsy
- multiple punch sizes available; bigger is better
- avoid using tissue cassettes unless samples are very small
- multiple/larger samples
what is incisional biopsy
- wedge of tissue removed from a larger lesion or organ
- avoid bloody or necrotic areas
- larger tissue samples
excisional biopsy
- usually elliptical excision
- surgical margins can be identified & evaluated to determine adequacy of excision
- submission of entire lesion
routine histochemistry
hemetoxylin & eosin (H&E)
special histochemistry
highlights specific features that are poorly discerned with H&E
immunohistochemistry
antibody-based detection of protein antigens in tissue sections
hematoxylin
basic dye that binds negatively charged substances (nuclei, ribosomes)
eosin
acidic dye that binds positively charged substances (cytoplasm, collagen, RBC)
immunohistochemistry (IHC)
target antigens
- cell structural components
- enzymes & hormones
- extracellular matrix components
- infectious agents
- cytokines & receptors
samples for ICH should be formalin-fixed, but ….
what happens when prolonged?
prolonged fixation can have adverse effects
what is an autopsy (necropsy)
a postmortem examination to discover the cause of death or extent of disease
why do an autopsy
- diagnostic (cause, heard health, zoonotic, closure)
- research
- teaching
- insurance requirement
- forensic
what does accurate diagnosis rely on
- clinical history and accompanying clinical data
- postmortem condition
- correct lesion identification and sampling
- accurate results of additional testing
final diagnosis
integration of all findings to provide a reasonable pathophysiologic explanation for disease/death
