Prostate gland & seminal vesicles

Benign mimickers of carcinoma

Postatrophic hyperplasia


Editorial Board Member: Debra L. Zynger, M.D.
Deputy Editor-in-Chief: Maria Tretiakova, M.D., Ph.D.
Kenneth A. Iczkowski, M.D.

Topic Completed: 2 December 2021

Minor changes: 2 December 2021

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PubMed Search: Postatrophic hyperplasia

Kenneth A. Iczkowski, M.D.
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Cite this page: Iczkowski KA. Postatrophic hyperplasia. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/prostatepostatrophichyper.html. Accessed December 8th, 2021.
Definition / general
  • Postatrophic hyperplasia (PAH) is a clustered, small acinar proliferation in fibrotic stroma, with a pseudoinfiltrative appearance
  • Among types of atrophy, this type is the most likely to mimic carcinoma
Essential features
  • Postatrophic hyperplasia is a small acinar proliferation with a special tendency to mimic cancer because it can show somewhat more prominent nucleoli than benign acini and because the stroma is fibrotic (Mod Pathol 2004;17:328)
  • Notable differences from cancer include a lobular or clustered arrangement of the acini around a central dilated duct space, lack of macronucleoli in most cells and retention of basal cells by immunostaining
  • There is no clinical significance and no need to specify in a pathology report
ICD coding
  • ICD-10: N40.1 - benign prostatic hyperplasia
Epidemiology
  • As with atrophy in general, postatrophic hyperplasia increases with age
Pathophysiology
  • Oxidative stress is implicated, similar to atrophy
  • Chronic inflammation is also present in all postatrophic hyperplasia cases, suggesting a connection (J Urol 2006;176:1012)
Etiology
Diagnosis
  • Histopathologic examination of tissue
Laboratory
Treatment
  • No treatment is needed
Gross description
  • No distinct findings
Microscopic (histologic) description
  • Usually has a central, dilated atrophic gland surrounded by clustered smaller glands within a fibrotic / sclerotic stroma; each lobular unit of acini is circumscribed
  • May have more prominent nucleoli than simple atrophy does and this heightens its ability to mimic cancer (Am J Surg Pathol 1998;22:1073)
Microscopic (histologic) images

Contributed by Kenneth A. Iczkowski, M.D.
Lobule of small acini

Lobule of small acini

Multiple clusters of acini

Multiple clusters of acini

Lobular arrangement of small acini

Lobular arrangement of small acini

Positive stains
Negative stains
  • AMACR / P504S should be mainly negative, as with atrophy in general
Molecular / cytogenetics description
  • Can have an elevated proliferation index that is greater than that of benign, nonatrophic acini and greater than that of simple atrophy (Am J Surg Pathol 1998;22:1073)
Sample pathology report
  • Prostate, biopsies:
    • Benign prostatic tissue (see comment)
    • Comment: Prostatic basal cell cocktail / P504S immunostain rules out cancer in the small acini.
Differential diagnosis
  • Carcinoma with an atrophic appearance or atrophic variant of prostatic adenocarcinoma:
    • Has a frankly infiltrative appearance, in which individual small cancer acini are interspersed between larger benign acini
    • Nuclear enlargement and prominent nucleoli are seen in a higher percent of cells than in atrophy
    • There is often concomitant presence of nonatrophic carcinoma
    • Can also have a sclerotic stroma
    • p63-, HMWK-
  • Simple atrophy:
Board review style question #1

Prostate tissue is shown. Which histologic finding, if it were present in this image, would make this proliferation of small acini suspicious for cancer?

  1. Central dilated duct space
  2. Clustered or lobular arrangement of the small acini
  3. Irregular and uncircumscribed infiltration of the small acini among larger definitely benign ones
  4. Prominent nucleoli in only a few cells and no nuclear enlargement
  5. Sclerotic stroma
Board review style answer #1
C. Postatrophic hyperplasia is shown. Irregular and uncircumscribed infiltration of the small acini would raise the suspicion of cancer. The clustered, lobular and circumscribed arrangement of the small acini (B) favors a benign diagnosis. The presence of the central dilated duct space (A) is also very characteristic of postatrophic hyperplasia. Sclerotic stroma (E) is a feature of postatrophic hyperplasia that can also occur in cancer and causes it to mimic cancer. Finally, as long as prominent nucleoli are visible in only a few cells (D) but not most cells, without nuclear enlargement (compared with other benign acini), that also is not suspicious for cancer.

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Reference: Postatrophic hyperplasia
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