Prostatic intraepithelial neoplasia (PIN)
High grade PIN - Flat pattern

Author: Nicholas Reder, M.D. (see Authors page)
Editor: Maria Tretiakova, M.D.

Revised: 27 October 2015, last major update October 2015

Copyright: (c) 2003-2015,, Inc.

PubMed Search: High grade prostatic intraepithelial neoplasia [title] flat pattern
Cite this page: High grade PIN - Flat pattern. website. Accessed March 20th, 2018.
Definition / general
Prognostic factors
  • Similar to other types of HGPIN
  • Risk of cancer on repeat biopsy compared to benign diagnosis:
    • Slightly increased in case of focal HGPIN (by ~5%)
    • Significantly increased in case of multifocal HGPIN (J Urol 2006;175:820)
  • Repeat biopsy is recommended for multifocal HGPIN within 1 year with relative increased sampling of the initial atypical site
Microscopic (histologic) description
  • Neoplastic proliferation within preexisting ducts and acini
  • One or two layers of cells lining glands without evidence of stratification
  • Cytologic changes include nuclear crowding, enlargement and numerous prominent nuclei
Microscopic (histologic) images
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Nuclear enlargement

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Flat pattern

Differential diagnosis