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Lymph Node Normal Morphology

Lymph Node Normal Morphology. Cortex Primary Follicle Secondary Follicle Mantle Zone Paracortex Medulla Sinuses. Cortex. Primary B-Cell Follicles Nodules of small lymphocytes Lack germinal centers Secondary B-Cell Follicles Result of stimulation Germinal Centers Mantle zone.

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Lymph Node Normal Morphology

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  1. Lymph Node Normal Morphology • Cortex • Primary Follicle • Secondary Follicle • Mantle Zone • Paracortex • Medulla • Sinuses

  2. Cortex • Primary B-Cell Follicles • Nodules of small lymphocytes • Lack germinal centers • Secondary B-Cell Follicles • Result of stimulation • Germinal Centers • Mantle zone

  3. Germinal Centers • Pale zone • toward antigen entry • small cleaved cells / centrocytes • follicular dendritic cells • Dark zone • toward paracortex • large lymphoid cells / centroblasts • tingible body macrophages

  4. Mantle Zone • polarized toward antigen entry • express bcl-2 protein

  5. Paracortex • rich in T cells • CD4:CD8 ratio variable • interdigitating dendritic cell • S-100 positive • irregular vesicular nuclei • high endothelial venules • postcapillary vessel • cuboidal epithelium

  6. Medullary areas • B cells predominate especially plasma cells • histiocytes

  7. Handling the Fresh Specimen • Surgeon should excise the largest and most abnormal node • Tissue for histology • Touch imprints • Fresh / frozen tissue for immunologic studies • Sterile portion for cytogenetics

  8. Frozen Section • Diagnostic frozen section should be discouraged • Use frozen to assess adequacy or triage tissue

  9. Freezing for Immunologic Studies • Liquid nitrogen or isopentane / dry ice mix is best • Thin sections (<2 mm )may be frozen in OCT • OCT must be wrapped in foil / plastic to avoid desiccation • Store at -70°C ideal but -20°C suitable for many antigens

  10. Fixation • Node sliced in 2-3 mm intervals • One metal based fixative (B5, Zenkers, zinc sulfate) • One neutral buffered formaldehyde (formalin)

  11. Processing • Single most important factor for optimal histology is section thickness • Sections should be one cell layer thick

  12. Routine Stains • H&E • Giemsa - highlight nuclear features, cytoplasmic granules and plasmacytoid features • PAS - highlights mucin and glycogen, immunoglobulin inclusions and blood vessels • Methyl-green pyronin - highlights plasmacytoid features

  13. Common Errors in Fixation and Processing • Drying of specimen - dark edge artifact; autolysis if prolonged • Section >3 mm thick - soft unfixed core; center cells show ballooning and are pale • Overfixation in B5 - brittle tissue; decreased nuclear staining • Inadequate dehydration - numerous cracks (dry earth look)

  14. Common Errors in Fixation and Processing • Paraffin too hot - muddy staining with poor detail • Improper sectioning - Venetian-blind effect; poor cytologic detail • Section drying too hot - bubbled nuclei and antigen loss

  15. Antibodies Employed in Paraffin Tissue Sections

  16. Antibodies Employed in Paraffin Tissue Sections

  17. Antibodies Employed in Paraffin Tissue Sections

  18. Antibodies Employed in Paraffin Tissue Sections

  19. Antibodies Employed in Paraffin Tissue Sections

  20. Antibodies Employed in Paraffin Tissue Sections

  21. Antibodies Employed in Paraffin Tissue Sections

  22. Antibodies Employed in Paraffin Tissue Sections

  23. Antibodies Employed in Fresh or Frozen Tissue

  24. Antibodies Employed in Fresh or Frozen Tissue

  25. Antibodies Employed in Fresh or Frozen Tissue

  26. Antibodies Employed in Fresh or Frozen Tissue

  27. Antibodies Employed in Fresh or Frozen Tissue

  28. Antibodies Employed in Fresh or Frozen Tissue

  29. Antibodies Employed in Fresh or Frozen Tissue

  30. Antibodies Employed in Fresh or Frozen Tissue

  31. Antibodies Employed in Fresh or Frozen Tissue

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