Prostate gland & seminal vesicles
Atypical / intraductal lesions
Low grade PIN

Topic Completed: 15 April 2015

Minor changes: 14 August 2020

Copyright: 2003-2020,, Inc.

PubMed Search: PIN [title] low grade

Nicholas P. Reder, M.D., M.P.H.
Maria Tretiakova, M.D., Ph.D.
Page views in 2019: 6,473
Page views in 2020 to date: 3,242
Cite this page: Reder NP, Tretiakova M. Low grade PIN. website. Accessed August 14th, 2020.
Definition / general
  • An intraepithelial proliferation along preexisting ducts and acini with mild atypia, at the lower end of the PIN spectrum
  • Do NOT include in pathology reports - variability in diagnosis exists even among experts (Am J Surg Pathol 1995;19:873)
  • Tends to be present in younger men, first appearing in men in their 30-40s (J Urol 1993;150:379)
  • No increase in prostate adenocarcinoma in patients with LGPIN (risk of carcinoma on subsequent biopsy is 18% as compared to 19% in a man with PSA levels of 4-10 ng/mL and an initial benign biopsy) (BJU Int 2011;108:1394)
Case reports
Microscopic (histologic) description
  • Architecture:
    • At scanning magnification darker and more complex than normal glands
    • Cellular crowding, pseudostratification with irregular spacing
    • Intact basal layer
  • Cytology:
    • Enlarged nuclei with increased variability in nuclear size and nuclear hyperchromasia
    • Indistinct and rare nucleoli
    • Amphophilic or eosinophilic cytoplasm
Microscopic (histologic) images

Images hosted on other servers:
Missing Image Missing Image

LGPIN, c/o Nicholas Reder, M.D.

Missing Image

LGPIN next to HGPIN, c/o Nicholas Reder, M.D.

Positive stains
Molecular / cytogenetics description
  • Usually diploid, in contrast with high-grade PIN, which can be aneuploid
Differential diagnosis
  • Benign central zone glands: can have complex architecture with papillary infoldings and pseudostratified epithelium, but lack nuclear atypia
  • Clear cell cribiform hyperplasia: clear cells forming crowded cribiform glands without atypia and with a very prominent basal cell layer
  • HGPIN: prominent nucleoli (1-3 microns in diameter), robust cellular crowding and multilayering
  • LGPIN-like low grade prostatic adenocarcinoma: lack of basal cells (Pathology 2014;46:88)
Back to top