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BASICS IN ANATOMICAL PATHOLOGY

Patient care is increasingly based upon information provided by examination of surgical specimens

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BASICS IN ANATOMICAL PATHOLOGY

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    1. BASICS IN ANATOMICAL PATHOLOGY

    2. Patient care is increasingly based upon information provided by examination of surgical specimens & biopsies

    3. Patient report must contain all data necessary for appropriate patient care

    4. The ultimate goal is to attain uniformity & consistency of included data found to be relevant to clinical management of patient

    5. Quality assurance in anatomical pathology : Goals : Accuracy Completeness Timeliness of all the reports

    6. Topics : Specimen collection Specimen handling Fixation Processing Tissue embedding Staining Cover slipping & slide mounting Reporting

    7. What should be considered by the surgeon : Sample collection : Preoperative consultation with pathology staff about : Requirements for selection , handling , transporting and processing of tissues Size of biopsy Number of biopsies Surgical margins

    8. What should be considered by the surgeon : Sample handling : Not slicing the tumor specimen Immediately placing the specimen into fixative

    9. Containers : Types : Reusable or Disposable Clean & uncontaminated Adequate size Labeled after placing the specimen

    10. Labeling : Two patient identifiers are required through the whole processing of the specimen : Patient , s name Patient , s date of birth Laboratory number Hospital number

    11. Fixation : Good preservation of tissue is the most important factor in the production of satisfactory histology slides

    12. Aims of fixation : To prevent autolysis or decomposition ( due to bacterial or osmotic change ) To preserve tissue as near to its original form as possible To protect tissue against subsequent changes during processing & embedding

    13. Aims of fixation : To give tissue a texture which permits easy sectioning To render the various constituents of the tissue reactive to the proposed stains

    14. Essentials to good fixation: Fresh tissue Proper penetration of fixative Right choice of a correctly formulated fixative

    15. No fixative will penetrate a piece of tissue ticker than 10 mm

    16. Solid organs : cut slices not ticker than 5 mm Hollow organs : open out or fill with fixative Large specimens : inject fixative along vessels (or bronchi in case of lungs )

    17. All fixative are used once only Adequate volume (> 2/3 of the container volume ) 10 times volume of fixative to tissue Fixation at room temperature ( not be heated )

    18. Types of fixatives

    19. Formalin : Commercially available solutions : 37 - 40 % formaldehyde in water Conventional fixation is usually carried out in 10% neutral buffered formalin ( NBF )

    20. Formalin : Suggested fixation time : >8 hrs 24 - 48 hrs for complete fixation (1/10 specimen to fixation ratio) Formalin in containers should be replaced weekly and a standard PH should be adopted.( either neutral or slightly acidic )

    21. Formalin benefits : Readily available Penetrates tissue quickly Long term storage in formalin is possible

    22. Formalin disadvantages : penetrates quickly but fixation is slow ( may not be complete with shorter times ) May not be suited to long term storage of tissue for ICC Hardens specimens Antigen cross-linking Partial Ag disappearance Special handling & disposal requirements

    23. Notice : HCL and formalin should be avoided in combination Formalin has respiratory and carcinogenic effects .

    24. Zinc formalin : Mixture of zinc sulfate and formalin Fixation time : 4 48 hrs ( 4 - 6 hrs for complete fixation )

    25. Zinc sulfate benefits : Shorter fixation time Minimal need for Ag unmasking or retrieval Preserve better tissue Ag morphology

    26. Zinc formalin disadvantages : Possible quenching of primary fluorescence Special handling and disposal requirements

    27. Alcohol / Acetone : As : 70 - 95 % Et OH 90 % Et OH / 10 % acetone For : Histopathology Cryostat frozen section Cytology smears

    28. Fixation time : Variable ( often in tissue processing secondary to formalin fixation ) 10 - 15 minutes for cryostat sections cytology smears

    29. Alcohol / Acetone benefits : Shorter fixation time ( 5 mm3 in 4 hrs ) Better cryostat sections Good preservation of cytoplasmic intermediate filaments

    30. Alcohol / Acetone disadvantages : quality and integrity of ICC staining ( especially after long term storage ) Ethanol has shrinking & hardening effects on tissues

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