HISTOPATHOLOGY

• Frozen section is a histopathology technique used for rapid diagnosis during surgery.
• • SPECIMENS SHOULD BE TRANSPORTED IN A COOLER WITH ICE PACKS OR IN A REFRIGERATED VAN.
• Histopathology is the study of abnormal body tissue and its components in the diagnosis of disease.
• Histopathologic technique involves the preparation of tissues thin enough for microscopic examination.
• Histopathology includes a series of tissue processing.
• 70% of all medical decisions are made based on laboratory diagnoses.
• The decision to collect specimens for pathological examination is made by physicians or nurses in clinical service with specialized knowledge of the disease and appropriate sampling method.
• Inappropriate sampling can result in poor specimen collection and negatively influence the final diagnosis.
• Specimens should be fixed to preserve them in a state as close to the living state as possible, and to protect against shrinkage, autolysis or bacterial action.
• All specimens must be submitted in an appropriate container or slide, labelled with the patient’s name, date of birth, unique identifier (e.g. hospital number), sampling site, date and time of specimen collection.
• The labels should be on the primary container (not the lid) and specimens from different sites or lesions from the same patient must be submitted in separate containers.
• A pathology request form should be completed with all relevant information needed for the pathologist to make an accurate diagnosis.
• All patient records are confidential and access should be limited to authorized personnel only.
• An incomplete form may require the laboratory to reject and return the specimen unprocessed.
• Cryostat is a refrigerated instrument used in fresh tissue microtomy.
• Immunofluorescent and IHC staining are techniques used in pathology.
• Retention of tissue blocks, slides and remnant tissue may be needed for future testing, second opinions or medicolegal purposes.
• Remnant tissue can be disposed of 30 days after the case is signed out officially by the pathologist.
• During the preparation of a cover slip, it is done to immobilize the cover slip and to avoid sticking of the slides upon storage.
• Optimum temperature for cryostat is -18 to -20ºC.
• Temperature range for cryostat is -5 to -30ºC.
• Patient data and reports should be retained for 10 years.
• Post-analytical phase involves reviewing slides and reporting results.
• Enzyme histochemistry is a diagnostic and research technique used to demonstrate soluble substances such as lipids and carbohydrates.
• Post-analytical phase involves archiving of patient data and report.
• Frozen section is used for rapid diagnosis during surgery.
• Process of indicating the year and specimen number on one end of the prepared slide for proper identification is known as labeling.
• Older data may be electronically archived or records may be stored offsite as long as retrieval does not hinder patient care.
• Locked cabinets for paper records and security codes for electronic systems are required and laboratory staff must be trained on maintenance of privacy and confidentiality of patient records.
• Tissue blocks and slides must be maintained for a minimum of 10 years.
• Providing comprehensive pathology reports cannot be overemphasized as their accuracy is fundamental to treatment decisions and good outcomes.
• As much clinical data as are available for a given patient should be provided to the pathologist; thus, direct, ongoing communications and/or a shared electronic medical record are crucial.
• Tissue processing involves 10 steps: Fixation, Dehydration, Clearing, Infiltration/Impregnation, Embedding/Casting/Molding/Blocking, Trimming, Section - Cutting (Micrometry), Staining, Mounting, Labeling.
• Analytical Phase: Tissue Processing
• Once specimens are mounted on glass sides, rehydration and staining are needed for examination under a microscope.
• Factors to consider prior to tissue processing include: Specimen should have a unique accession number for easy tracking, Tissue must be cut to fit easily in a standard cassette (3 x 2.5 x 0.4 cm), Recommended tissue size: 2cm^2 x no more than 4mm thick, Section the specimen to 4 - 6mm thick with both surfaces parallel, Fatty tissues must be cut very thin to fix and dehydrate well, Minute tissue fragments must be wrapped in lens.
• The primary aim of tissue processing is to preserve the morphologic and chemical integrity of the cell in as life-like manner as possible.
• For Histopathology, Haematoxylin and Eosin (H&E) stain is used as a routine stain and plays a critical role.
• After staining, slides are dehydrated (Xylene: Dealcoholization), and covered by mounting media and thin cover glasses (cover slip) that harden and seal the preparation to make them permanent.
• Special stains and immunohistochemical stains are used when H&E does not provide all the information the pathologist needs.