SURGICAL PATHOLOGY LABORATORY
Surgical Pathology: is the study of lesions of living tissues and cells that are the result of a disease, a trauma , or a malformation
Autopsy : post-mortem examination to discover the cause of death or the extent of disease.
Most of the surgical specimens come from the operating rooms
Others come from emergency rooms or clinics
There are two types of specimens:
There are various Histotechnological Techniques
Cytology:
Gross Examination :
The specimen is properly identified and labeled after its reception in the laboratory.
A properly completed surgical pathology request form contains :
Steps to examine material in container
Inadequate gross dissection and sampling will invalidate the microscopic description
A crucial part of pathologic examination is dissection, gross description and selection of sections for microscopic study.
It cannot be remedied if done poorly at the time of the initial workup.
If microscopic description is inadequate, the slide can be reviewed.
Gross examination is crucial because the tissue will be sampled and submitted to histology accordingly.
The specimen is kept wet for 2-3 months
Fixation
Preserves tissues by stopping autolysis
Fixation is accomplished by immersion or perfusion
Mechanism of action: modification of spatial configuration of proteins (denaturing)
Groups of Fixatives
Formalin
is a 10% buffered neutral solution
Tissue Processing
There are 3 sequential steps designed to remove extractable water from tissue specimens and replace it with a medium that solidifies to allow sectioning:
Processing is done by automatic tissue processor as an overnight schedule that enhances the processing by using heat, vacuum, pressure and agitation
Embedding
is the process of surrounding tissue with a firm substance to facilitate the cutting of the sections
Microtomy
The parafin block is inserted in a rotary Microtome
the sections are separated and placed onto a clean pre-marked slide
Staining and mounting
Hematoxylin and eosin (H&E) is a routine stain by which all tissues pass by
The hematoxylin stains nuclei in blue
The Eosin stains cytoplasm in pink or red
It shows the morphology of the tissue
If special biochemical structures are to be stained: special stains for carbohydrates, lipids, amyloid, connective tissue fibers, microorganisms, pigments and minerals
Mounting
Final step in preparation of a slide
Cover the portion containing the tissue with a thin glass: coverslip
This makes the slide permanent and permits microscopic examination
Protects tissue from being scratched and preserves the slide for the years to come.
Mounting media: synthetic resinsFinal step in preparation of a slide
Frozen Section
Sectioning frozen tissue, the tissue being hardened by freezing the water that it contains.
Fresh or fixed tissues are frozen and sectioned instead of being routinely processed and embedded.
Sections done in Cryostat: Microtome in a deep freeze at -20ºC.
Cytology
Cytopathology = study of disease in cells
Exfoliative cytology
Aspiration cytology
Papanicolaou or Pap stain; Main stain for cytologic preparationsCytopathology = study of disease in cells
Cell
is the functional unit of all tissues
is the structural unit of all living organisms
has the capacity to perform individually all the essential life functions
Cell structure
Two components:
Both have subcellular elements called organelles
can be looked under :
Smaller structures seen by biochemical techniques (histochemistry) and immunological techniques (immunohistochemistry)
The cell nucleus
DNA < 20%
Some RNA: messenger, transfer and ribosomal RNA
Nucleoprotein associated with DNA:
Chromatin: chromosomes in a different degree of coiling in nondividing nuclei or coiled strands of DNA bound to basic proteins (histones): The DNA is associated with proteins to form chromatin.
Nucleolus :spherical structure up to 1 mm in diameter, rich in rRNA and protein.
Basophilic on light microscope: H&E.
Large nucleoli present in cell proliferation, regeneration, in rapidly growing malignant tumors
- antihistones