American Urological Association - Atypical Small Acinar Proliferation (ASAP)
Atypical Small Acinar Proliferation (ASAP)
- 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.
- 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.