OrthoFracs Logo

Histopathology of Tumours

Grading Neoplasia

  • Most important
    • Mitotic Figures
    • Necrosis
  • Next
    • Anaplasia
    • Pleomorphism
    • Atypia

Techniques

Standard Microscopy

  • Specimen fixed in Formalin
    • Decalcified if contains bone/ calcium
  • Embedded in Paraffin
    • Water replaced with wax
  • Fine sections cut
  • Stained with Haematoxylin & Eosin
    • Haematoxylin stains Protein blue
    • Eosin stains Cytoplasm & Collagen pink

Special Stains

  • Van Gieson's
    • Myogenic Tumours
  • Reticulin
    • Vascular tumours
    • Clear cell Sarcoma
    • Alveolar Soft Part Sarcoma
  • Periodic Acid Shift
    • Ewing's/ PNET
    • Rhabdomyosarcoma
    • Neuroblastoma
  • Melanin
    • Melanoma
  • Masson's Trichrome Stain
    • Fibrosarcoma (detects presence of collagen)

Frozen Section

  • Specimen fresh
  • Specimen frozen with liquid N²
  • Fine sections cut
  • Similarly stained

Electron Microscopy

  • Rationale
    • Certain ultrastructural features differentiate tumour types
  • Differentiate PNET/ Ewing's / Neuroblastoma
  • Epithelial structures in carcinoma
  • Sarcomeres in Myosarcoma
  • Melanosomes in Melanoma

Immunohistochemical Stains

  • Rationale
    • Identifies certain proteins
  • Technique
    • Slide prepared as above
    • Particular Antibody-containing solutions put on slide
      • Antibody binds with antigen if particular protein present
      • Then another antibody with attached colouring agent put on slide
      • Binds to antigen-antibody complex if present
    • Thus stains if protein of interest present
  • Types IHC Stains
Types IHC Stains
S100
  • Melanoma
  • Schwann/ Neural cells
  • Ewing’s / PNET
  • Actin
  • Muscle, Myofibroblasts
Desmin
  • Muscle
Myoglobin
  • Skeletal muscle only
Vimentin
  • Everything
LCA
  • Lymphoma
Cytokeratin
  • Skin
  • Synovial Sarcoma
  • Epithelioid Sarcoma
Epithelial Membrane Antigen
  • Synovial Sarcoma
  • Epitheliod Sarcoma
NSE, GFAP, Neurofilament PR
  • Round Cell Tumours

DNA Ploidy

  • Measure DNA content in each cell by flow cytometry
  • Quantify number of cells with normal & abnormal amounts DNA
  • Normal 23 pairs (Diploid) or 46 total
  • Little benefit as
    • Can't use it to grade neoplasia
    • Can't use it for prognosis
    • Can't diagnose tumour type

Cytogenetics

  • Rationale
    • Certain tumours have identified genetic abnormalities
      • Ewing’s/ PNET t(11,22)
      • Synovial Sarcoma t(X, 18)
      • Liposarcoma
      • Rhabdomyosarcoma
      • Infantile Fibrosarcoma Trisomy 11,17,20
      • Clear Cell Sarcoma t(11, 22)
  • Technique
    • Cells cultured
    • Halted in Metaphase
    • Karyotyping performed
    • Chromosomal banding patterns identified
Bookmark and Share