Prostate gland & seminal vesicles

Acinar / ductal adenocarcinomas

Acinar adenocarcinoma

Microcystic pattern


Editorial Board Member: Bonnie Choy, M.D.
Deputy Editor-in-Chief: Maria Tretiakova, M.D., Ph.D.
Ankur Sangoi, M.D.

Last author update: 17 July 2023
Last staff update: 21 November 2023

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PubMed Search: Microcystic adenocarcinoma

Ankur Sangoi, M.D.
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Cite this page: Sangoi A. Microcystic pattern. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/prostatemicrocystic.html. Accessed March 28th, 2024.
Definition / general
  • One of the unusual histological patterns of acinar adenocarcinoma
  • While often easier to recognize at radical prostatectomy given the juxtaposition to usual pattern acinar adenocarcinoma (incidence of 11%), deceptive morphology can be challenging to recognize on prostate biopsy (incidence of 1%) (Am J Surg Pathol 2010;34:556, Int J Surg Pathol 2020;28:584)
  • As these are graded in the usual fashion, formal designation as microcystic pattern is not indicated in the pathology report and is more important to recognize for accurate diagnosis
Essential features
  • Cystic glands with marked dilatation (reminiscent of cystic atrophy) at low power magnification but often showing luminal crystalloid, blue intraluminal mucin and prominent nucleoli at higher power magnification
Terminology
  • Sometimes synonymous with pseudohyperplastic pattern prostatic adenocarcinoma
ICD coding
  • ICD-O: 8140/3 - acinar adenocarcinoma
  • ICD-10: C61 - malignant neoplasm of the prostate
  • ICD-11: 2C82.0 & XH4PB1 - adenocarcinoma of prostate & acinar adenocarcinoma of prostate
Sites
  • Prostate
Diagnosis
  • Core needle biopsies or transurethral resection of the prostate
  • Immunohistochemistry may be used to confirm the absence of basal cells
Case reports
Microscopic (histologic) description
  • Cystic glands with marked dilatation (reminiscent of cystic atrophy; glands can become quite attenuated), approximately 10x the size of typical malignant acini (Am J Surg Pathol 2010;34:556)
  • Sometimes crowded growth at low power magnification but often showing luminal crystalloid, blue intraluminal mucin and prominent nucleoli at higher power magnification
  • Typically coexists with usual acinar pattern prostatic adenocarcinoma
  • One of the important deceptively bland histological patterns of prostate cancer, alongside atrophic, pseudohyperplastic and foamy gland prostatic adenocarcinoma
Microscopic (histologic) images

Contributed by Ankur Sangoi, M.D.
Compact dilated cysts Compact dilated cysts

Compact dilated cysts

Basal nuclei with amphophilic cytoplasm

Basal nuclei with amphophilic cytoplasm

Prominent nucleoli and luminal crystalloid

Prominent nucleoli and luminal crystalloid

Cytoplasmic P504S

Cytoplasmic P504S

Positive stains
Negative stains
Sample pathology report
  • Same as typical acinar adenocarcinoma; it is not needed to report the presence of this histological pattern
  • Prostate, radical prostatectomy:
    • Prostatic adenocarcinoma, Gleason score 3 + 3 = 6, grade group 1 (see synoptic report)
Differential diagnosis
Board review style question #1

Which of the following statements is true regarding microcystic pattern prostatic adenocarcinoma?

  1. It is one of the patterns of prostatic adenocarcinoma that is excluded from grading
  2. It most closely mimics cystic atrophy but shows an immunoprofile of usual acinar adenocarcinoma (cytoplasmic P504S, loss of basal cell reactivity)
  3. It rarely shows luminal crystalloid or prominent nucleoli
  4. It shows atrophic glands with aberrant nuclear positivity for p63
Board review style answer #1
B. It most closely mimics cystic atrophy but shows an immunoprofile of usual acinar adenocarcinoma (cytoplasmic P504S, loss of basal cell reactivity). Answer A is incorrect because Gleason grading is applicable to microcystic pattern prostatic adenocarcinoma (graded on architecture, usually Gleason grade 3 + 3). Answer C is incorrect because it often shows luminal crystalloid with prominent nucleoli. Answer D is incorrect because it does not show features of p63 positive prostatic adenocarcinoma (atrophic glands with aberrant nuclear positivity for p63).

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Reference: Microcystic adenocarcinoma
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