PIN


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  • Clinical

    • PIN by itself doesn't elevate PSA
    • Coexsit with cancer in >85%
    • peripheral zones

  • Histology

    • intraepithelial, so has intact basement membrane
    • architecture
      • crowding, stratification, irregular spacing
      • HGPIN can be flat, tufting, micropapillary, cribriform
      • HGPIN can have loss of basal layer
    • cytology
      • nuclear enlargement, pleomorphism
      • luminal polarization of nuclei
      • HGPIN has prominent nucleoli
    • variants
      • signet ring
      • mucinous
      • foamy
      • inverted
      • small cell neuroendocrine
    • grading
      • low grade: piling up of cells
      • high grade: ugly cytology
      • high grade PIN with adjacent small atypical glands
      • grading is based on worst grade, usually located peripherally

  • Stains

    • p63 stains basal cell layer
    • racemase (AMACR) stains cancer cells
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