2020 Edition
| Editors: Maria Rosaria Raspollini, Antonio Lopez-Beltran

Atypical Small Acinar Proliferation

  • Alessia Cimadamore
  • Silvia Gasparrini
  • Rodolfo MontironiEmail author
Reference work entry
DOI: https://doi.org/10.1007/978-3-030-41894-6_4782


Prostate tissue with small focus of atypical glands


Atypical Small Acinar Proliferation (ASAP) suspicious for, but not diagnostic of, adenocarcinoma (Epstein and Herawi 2006; Montironi et al. 2006).

Clinical Features

  • Incidence

    5% of prostate biopsies

  • Age

    The same age as prostate cancer (mean 65.8 years (Range 44–80)).

  • Sex


  • Sit

    All prostate zones.

  • Treatment

    Definitive therapy (either surgical or nonsurgical) discouraged. Repeat biopsy and follow-up (Borboroglu et al. 2001).

  • Outcome

    Risk of detection of carcinoma on needle core re-biopsy: 40%.


  • Focus of small size.

  • Small acinar proliferation.

  • Small number of cells with enlarged nucleoli.

  • No basal cells in the initial H&E-stained sections (Egevad et al. 2006; Epstein 1998; Epstein and Herawi 2006; Montironi et al. 2006).


Basal cell markers and racemase: The former are absent in prostate cancer and the latter is expressed in 80% of cancers (See differential diagnosis and specific items)...
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References and Further Reading

  1. Borboroglu, P. G., Sur, R. L., Roberts, J. L., & Amling, C. L. (2001). Repeat biopsy strategy in patients with atypical small acinar proliferation or high grade prostatic intraepithelial neoplasia on initial prostate needle biopsy. The Journal of Urology, 166, 866–870.CrossRefGoogle Scholar
  2. Egevad, L., Allsbrook, W. C., & Epstein, J. I. (2006). Current practice of diagnosis and reporting of prostatic intraepithelial neoplasia and glandular atypia among genitourinary pathologists. Modern Pathology, 19, 180–185.CrossRefGoogle Scholar
  3. Epstein, J. I. (1998). Atypical small acinar proliferation of the prostate gland. American Journal of Surgical Pathology, 22, 1430–1431.CrossRefGoogle Scholar
  4. Epstein, J. I., & Herawi, M. (2006). Prostate needle biopsies containing prostatic intraepithelial neoplasia or atypical foci suspicious for carcinoma: Implications for patient care. Journal of Urology, 175, 820–834.CrossRefGoogle Scholar
  5. Montironi, R., Scattoni, V., Mazzucchelli, R., Lopez-Beltran, A., Bostwick, D. G., & Montorsi, F. (2006). Atypical foci suspicious but not diagnostic of malignancy in prostate needle biopsies (also referred to as “atypical small acinar proliferation suspicious for but not diagnostic of malignancy”). European Urology, 50, 666–674.CrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2020

Authors and Affiliations

  • Alessia Cimadamore
    • 1
  • Silvia Gasparrini
    • 1
  • Rodolfo Montironi
    • 1
    Email author
  1. 1.Institute of Pathological Anatomy and HistopathologyPolytechnic University of the Marche Region (Ancona), United Hospitals AnconaAnconaItaly