Prostate gland

The prostate adds juice to the sperm. In old men it creates lotsa problems... nodular hyperplasia (commonly called BPH or benign prostatic hypertrophy) and cancer (adenocarcinoma).

Normal

• Glands have two cell layers (similar to glands in breast).
  • Second cell layer may be difficult to see (like in breast).
• Epithelium in glands fold.
  • Very important - helps on differentiate from Gleason pattern 3.
• Luminal epithelium often clear.

• No nucleoli present (if you see nuclei think: cancer, HGPIN, reactive changes, basal cell hyperplasia).
• Single nucleus.
• No mitoses - these are uncommon... even in high grade prostate cancer.

• Corpora amylacea.
  • Round/ovoid-eosinophilic bodies -- with laminations (layered appearance).
  • In gland lumina.
  • Usually in benign glands - but cannot be used to exclude cancer.
  • Very common.
  • These should be differentiated from eosinophilic proteinaceous debris - which is associated with cancer.

• Mucinous glands at the apex of the prostate = Cowper's gland (AKA bulbourethral gland), resemble (mucinous) salivary glands.

IHC

Normal prostate: AMACR-, p63+, HMWCK+, PSA+, PSAP+.

Common diagnoses

• Benign.
  • Atrophy (may be resemble adenocarcinoma).
• Prostate adenocarcinoma.
  • Most common Grade is 3+3=6.
• HGPIN (high-grade prostatic intraepithelial neoplasia).
• ASAP (atypical small acinar proliferation) - used if you have a few abnormal appearing glands... but can't decide between prostate adenocarcinoma & benign.
• Chronic inflammation.
• Acute inflammation - can result in an elevated PSA and may have prompted the biopsy you're looking at.

Cancer

Criteria as a list

Major criteria:

1. "Infiltrative growth" pattern.
2. Lack of basal cells.
3. Nuclear enlargement.
4. Nucleoli.

Minor criteria:

1. Nuclear hyperchromasia.
2. Wispy blue mucin.
3. Pink amorphous secretions.
4. Intraluminal crystalloid.
5. Amphophilic cytoplasm.
6. Adjacent HGPIN.
7. Mitoses.

Low power features

• Architecture is the key to diagnosing low grade cancer.
  • Back-to-back glands or crowding of glands -- think low grade cancer (Gleason pattern 3).
  • Sharp transition between gland border and lumen.
    • Loss of epithelial folding at the epithelium-gland lumen interface - "punched-out" appearance.
  • Eosinophilic proteinaceous debris within the gland lumen.

High power features

• Nuclei.
  • Hyperchromatic nuclei (like in HGPIN).
  • Nuclear largement.
    • Difficult to appreciate (if cancer isn't side-by-side with normal prostate).
    • Difficult to see if not on high power.
• Nucleoli visible on high power (200x or 100X)
  • May be difficult to see - especially if light intensity is low.
    • One should not use 400x to look for nucleoli (it is a waste of time + you risk overcalling something benign).
  • If I see three good nucleoli in a gland I'm usually confident it is cancer.
• Loss of basal cells - diagnostic feature.
  • Like in breast pathology (where one looks for loss of myoepithelial cells) - this may be difficult to see.

Notes:

• Mitoses are not a common feature - don't waste time looking for them.

IHC

• AMACR +ve, p63 -ve, HMWCK (34betaE12) -ve .
• Usually positive: PSA, PSAP.

Grading

There is only one grading system that any one talks about...

Gleason grading system

• Score range: 2-10.
• Reported as: (primary pattern) + (secondary pattern) = sum.
  • e.g. Gleason grade 3+4=7 means: pattern 3 is present and dominant, pattern 4 is present but in a lesser amount than pattern 3.

Gleason pattern 1 & 2

• Academic thing - you can forget about 'em.

Gleason pattern 3

• Glands smaller than normal prostate glands + loss of epithelial folding.
• Can draw a line around each gland.
• Benign looking cribriform.
  • Small and circular.

Gleason pattern 4

• Loss of gland lumina.
• Gland fusion.
• Benign looking cords ('hypernephroid pattern').
• Most cribriform.
• One gland is not enough to call Gleason 4.

Gleason pattern 5

• Sheets.
• Single cells.
  • May be confused with stromal/lymphocytic infiltration.
    • Look for nucleoli, cells should be round (prostatic stroma cells are spindle cells).
• Cords.
• Nests of cells with necrosis at centre.

Testing yourself:

• There is a nice test-yourself quiz from Johns Hopkins: http://162.129.103.34/prostate/.
  • It was studied in a paper by Kronz et al..

Management

The management changes between Gleason 6, 7 & 8; typically, the implications are:

• Gleason 6: watchful waiting or radioactive seeds, surgery if patient wants.
• Gleason 7: do something.
• Gleason 8+: bad cancer - do something quickly!

Bottom line: You want to be sure when you call something Gleason pattern 4.

Note:

• The usual caveats apply to the above; if the patient is moribund-- nothing is done, if the patient refuses treatment... nothing is done et cetera.

Margins + Extension

Definitions:

• Extraprostatic extension (EPE) is difficult to assess as there is consensus definition.
  • The prostate does NOT have a well defined capsule.
    • Intraobserver agreement for EPE is fair-moderate and lower than for the surgical margin.
• Surgical margin - where the surgeon cut.
  • It is possible to have EPE without a positive margin.
  • It is possible to have a positive margin without EPE.

Extraprostatic extension (EPE)

• Prostatectomy specimens: EPE is present if there is a "significant bulge" in the contour of the prostate at low power.
• Prostate biopsy: EPE is present if tumour touches adipose tissue.
  • The prostate, at the apex, may have some skeletal muscle -- it is hard to define the extent... ergo no EPE at apex. (????)

Elements of a prostate biopsy report with cancer

1. Type of cancer, e.g. "prostatic adenocarcinoma, acinar type".
2. Gleason score including primary and secondary pattern, e.g. "Gleason score 3+4=7".
3. Number of cores involved, e.g. "2/3 cores involved".
4. Percent area involved, i.e. how much of the core is cancer, e.g. "75% of specimen is tumour".
5. Percent area involved that is Gleason pattern 4 or 5, e.g. "25 of the tumour is Gleason pattern 4 or 5".
6. Presence of perineural invasion.
7. Presence of extension into fat (extraprostatic extension).

Notes:

• "Percent area involved" may seem like an odd thing to request 'cause it is sampling dependent, i.e. if the radiologist sticks the biopsy needle deeper into the lesion more of the core is positive, but urologists think it is important -- more important than perineural invasion.

HGPIN (high grade prostatic intraepithelial neoplasia)

• Diagnosed on basis of nuclear changes.
  • Hyperchromatic nuclei.
  • Nucleoli present.
  • Often increased N/C ratio.
• Different architectures (e.g. papillary).
• Usually epithelial hyperplasia.

Note: Low grade PIN (LGPIN) is never diagnosed. It was found to be a useless diagnosis with no significant prognostic significance.

HGPIN architecture

There are several forms:

• Flat.
• Tufting.
• Micropapillary.
• Cribriform.

Note: The architectural pattern is NOT thought to have any prognostic significance -- may, however, be useful for picking it out from benign prostate.

Differentiating between diagnoses

HGPIN vs. adenocarcinoma:

• Glands with HGPIN have two or more distinct cells layers.

HGPIN vs. normal:

• HPGIN has nuclear changes.

May need IHC (especially for cancer vs. HGPIN).

IHC patterns:

• Cancer: AMACR+, p63-, HMWCK-.
• HGPIN: AMACR+, p63+, HMWCK+.
• Normal: AMACR-, p63+, HMWCK+.

Reporting prostate cancer

Biopsy reports

Important elements:

• Diagnosis.
  • Specific subtype (usually acinar adenocarcinoma).
  • Gleason score, e.g. 4+3=7.
• Number of cores.
• Number of cores involved.
• Percentage of core surface area involved (estimated).
• Percentage of tumour that is Gleason pattern 4 or 5.

Prostatectomy specimens

See: CAP checklist.

Atrophy

• Small glands (may mimic Gleason score 3 pattern).
• Glands often have a jagged edges/prows (in cancer the glands tend to have round edges).
  • Prow = forward most part of a ship's bow that cuts through the water.
    • You may have come across prow in the context of breast cancer, i.e. tubular carcinoma.
• Atrophic glands are often hyperchromatic.

Negatives:

• Nuclei like normal.
• Should have two cell layers, i.e. epithelial and myoepithelial (may be difficult to see).

Differentiating between diagnoses

Atrophy vs. low grade cancer (Gleason pattern 3)

• Atrophy - has two distinct cells layers in the gland.
• Atrophy - has an acinar arrangement/look like they originate from one large duct.
• Cancer - glands are back-to-back and do not look like they originate from one large duct.
• Cancer - has nucleoli (atrophy does NOT).

Basal cell hyperplasia

• Atypical appearing glands - typically in transition zone.
• May have nucleoli.

Differentiating between diagnoses

Basal cell hyperplasia vs. cancer[3]

• Low power gland architecture near normal.[4][5]
  • Glands not as small as cancer.
  • Folds in gland lumina.
  • No hyperchromasia.
  • Two cell layers (as in normal prostate glands).

Atypical small acinar proliferation

General

• Abbreviated ASAP.
• Can be considered to be a waffle diagnosis... like ASCUS is on the pap test.
• Should be used sparingly.
• Never diagnosed on excision, i.e. prostatectomy specimen.
• Some experts consider this diagnosis bogus, i.e. some don't believe it exists.

Histologic characteristics

• Atypical appearing acini.
• Limited extent, e.g. 2-3 glands.
• IHC not contributory.
• Deeper cuts didn't yield anything.

Association with adenocarcinoma

• On subsequent biopsy - chance of finding adenocarcinoma is approximately 40%; this is higher than if there is high-grade prostatic intraepithelial neoplasia (HGPIN).

Management

• ASAP is considered an indication for re-biopsy; in one survey of urologists 41/42 (~98%) of respondents considered it a sufficient reason to re-biopsy.

Ref.:ASAP (en.wikipedia.org).

See also

• Urothelium.
• Genitourinary pathology.

External links

• CAP prostate check list - cap.org.
• CAP prostate protocol - cap.org.
• Gleason score quiz - Johns Hopkins Prostate Center.