American Urological Association - Atypical Small Acinar Proliferation (ASAP)

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Atypical Small Acinar Proliferation (ASAP)

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  • Focus of atypical glands in needle biopsy that is quantitatively &/or qualitatively insufficient for definitive diagnosis or exclusion of prostate cancer.
  • Not an entity, but a spectrum of different entities and include under sampled prostate cancer and its various benign mimics.
  • Descriptive diagnosis to guide subsequent management.
    • Repeat biopsy is indicated with ASAP diagnosis.
  • Reasons for ASAP diagnosis by pathologists:
    • Quantitative factor, such as too few atypical glands (<3) (image A), (image B), (image C),
      & (image D).
    • Qualitative factors, such as insufficient architectural or cytologic features or no pathognomonic features of cancer.
    • Compounding features such as obscuring inflammation, crushing artifacts and poor cytological detail.

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  • Examples of benign mimic of cancers:
    • Benign crowded glands and processes (atrophy, HGPIN, adenosis, sclerosing adenosis and basal cell hyperplasia).
    • Non-prostatic structures within or near prostate (seminal vesicle or ejaculatory duct and Cowper's gland).
    • Rare benign processes (mesonephric remnants, nephrogenic adenoma and verumontanum gland hyperplasia).
  • ASAP diagnosis carries higher risk of finding prostate cancer in re-biopsy (40-50%; individual series vary between 17-70%).
  • Subsequent prostate cancer may also be in contralateral side (up to 27%).
  • Most prostate cancer on subsequent re-biopsy are Gleason score 6 (up to 80%).
  • Some recommend qualifying ASAP, such as "suspicious" or "highly suspicious for cancer", to convey the risk in ASAP diagnosis and need for re-biopsy.

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