Specialty Guide · Path-iQ Global Pathology Review
Prostate pathology is dominated by the diagnostic and prognostic implications of Gleason grading — refined through four decades from Gleason's original 1966 system to the ISUP 2014 and 2019 consensus revisions — and by a rapidly expanding molecular landscape (ERG fusion, PTEN deletion, CDK12 biallelic loss, BRCA1/2) that drives not only prognosis but PARP inhibitor and immunotherapy eligibility in castration-resistant disease.
The Gleason grading system assigns grades 1–5 to prostate carcinoma based on architectural growth patterns. The original Gleason score (GS) was the sum of the primary (most prevalent) and secondary (second most prevalent) pattern. The 2005 and 2014 ISUP modifications standardised pattern definitions and created Grade Groups (GG 1–5) to simplify communication and improve outcome stratification. The 2019 ISUP consensus further refined several borderline patterns.
| Gleason Pattern | Architecture | 2019 ISUP Key Points |
|---|---|---|
| Pattern 3 | Discrete, well-formed, individual glands; small to medium sized; infiltrating between normal glands; no cribriform structures | Cribriform glands are NEVER pattern 3 — any cribriform architecture = pattern 4 minimum. Small poorly-formed glands adjacent to well-formed glands = still pattern 3 if truly individual gland units |
| Pattern 4 | Fused glands (sharing walls); cribriform glands (intraluminal bridging); poorly formed glands (glomeruloid structures, irregular nests with no lumen); hypernephromatoid pattern | Cribriform pattern 4 is the most important 2019 update: any cribriform gland = pattern 4; large cribriform glands = intraductal carcinoma (IDC) until proven otherwise; glomeruloid structures = pattern 4 |
| Pattern 5 | Solid sheets, cords, single cells; no gland formation; comedonecrosis within cribriform glands | Necrosis within cribriform structures = pattern 5 (not pattern 4). Signet ring-like cells = pattern 5 |
| Grade Group | Gleason Score | Gleason Pattern Sum | 10-yr BCR-Free Survival (RP) | Clinical Tier |
|---|---|---|---|---|
| GG 1 | GS ≤6 | 3+3 | ~96% | Very low / low risk; active surveillance candidate |
| GG 2 | GS 7 (3+4) | Predominantly pattern 3; minor pattern 4 | ~88% | Intermediate favourable; active surveillance in select cases (very low volume) |
| GG 3 | GS 7 (4+3) | Predominantly pattern 4; minor pattern 3 | ~63% | Intermediate unfavourable; radical treatment indicated |
| GG 4 | GS 8 (4+4, 3+5, 5+3) | All pattern 4 OR any pattern 5 ≤ pattern 4 | ~48% | High risk; multimodal treatment |
| GG 5 | GS 9–10 (4+5, 5+4, 5+5) | Predominantly or exclusively pattern 5 | ~26% | Very high risk; multimodal treatment ± systemic therapy |
Two architectural features have emerged as particularly strong adverse prognostic indicators, now driving significant attention in prostate pathology:
Cribriform Gleason pattern 4 (defined as intraluminal bridging forming a sieve-like structure within a gland space) carries significantly worse prognosis than non-cribriform pattern 4 (fused glands, poorly formed). Studies from multiple institutions show that cribriform pattern 4 is an independent predictor of metastasis and prostate cancer-specific mortality, even after controlling for GG, stage, and PSA. The 2019 ISUP consensus recommends reporting the presence or absence of cribriform architecture specifically on all prostate carcinoma specimens.
IDC-P represents spread of high-grade carcinoma into and along pre-existing prostatic ducts and acini, with expansion of the involved structures. It is not an in-situ lesion — it is associated with synchronous high-grade invasive carcinoma and correlates with more advanced stage, nodal metastasis, and shorter biochemical recurrence-free survival after radical prostatectomy. Key diagnostic criteria for IDC-P (Guo and Epstein, 2006): large cribriform or solid glands occupying pre-existing duct/acinar spaces, with either dense cribriform filling (>50% of luminal space) or comedonecrosis, or two or more of: marked nuclear atypia, mitotic figures, or intraluminal proliferation. The basal cell layer may be retained (identified by p63 or CK34βE12) — presence of a basal layer helps identify the pre-existing ductal space. IDC-P on biopsy should be reported separately from invasive carcinoma and is a strong indication for radical treatment.
| Element | Biopsy | Radical Prostatectomy |
|---|---|---|
| Histological type | Acinar adenocarcinoma (specify if variant: ductal, mucinous, neuroendocrine) | Same; specify if mixed or treatment-effect |
| Grade Group (GG) | GG 1–5 per ISUP 2019; report GG per core and overall GG | Overall GG + GG per tumour focus if multiple tumours |
| Cribriform / IDC-P | Present or absent (required per 2019 ISUP) | Present or absent; IDC-P extent |
| Tumour extent | Number of positive cores / total cores; % tumour in each positive core; largest linear mm of carcinoma | Tumour size (largest dimension); dominant tumour location |
| Perineural invasion (PNI) | Present or absent; not required for biopsy staging but prognostic | Present or absent; extent |
| Extraprostatic extension (EPE) | Not applicable | Absent / focal (<1 HPF beyond capsule) / established (>1 HPF); location |
| Seminal vesicle invasion (SVI) | If SV biopsy included | Present or absent (pT3b if positive) |
| Surgical margins | Not applicable | Negative / positive (specify site, GG at margin, linear extent in mm) |
| Lymphovascular invasion (LVI) | Present or absent | Present or absent |
| AJCC pT stage | Not applicable to biopsy | pT2a–pT4 per 8th edition AJCC |
| Marker | Carcinoma | Benign | Use |
|---|---|---|---|
| AMACR (P504S, α-methylacyl-CoA racemase) | Positive (cytoplasmic granular) | Negative | Confirms carcinoma in ambiguous cases; strong in most acinar adenocarcinomas; weak/absent in atrophic and foamy gland carcinoma — don't rely on alone |
| p63 | Negative (no basal cells) | Positive (basal cells) | Loss of basal cells in suspicious glands → supports carcinoma; helps identify IDC-P (retained basal layer in duct); positive in high-grade PIN (discontinuous) |
| CK34βE12 (CK903) | Negative | Positive (basal cells) | High molecular weight cytokeratin — basal cell marker; complement or alternative to p63 for basal cell identification |
| CK5/6 | Negative | Positive (basal cells) | Alternative basal cell marker; less specific than p63 or CK34βE12 |
| PSA (prostate-specific antigen) | Positive | Positive | Prostate origin marker in metastatic setting; high-grade prostate Ca may lose PSA → NKX3.1 more sensitive |
| NKX3.1 | Positive (nuclear) | Positive | More sensitive than PSA for high-grade prostate Ca; combined PSA+NKX3.1 panel for metastatic workup |
| ERG (ETS-related gene) | Positive in ~50% (nuclear; marks TMPRSS2-ERG fusion) | Negative (benign glands negative; HGPIN may be positive) | Diagnostic marker for prostate carcinoma with TMPRSS2-ERG fusion; absence does not exclude carcinoma |
| PTEN (IHC for loss) | Loss in ~20–30% (especially high-grade) | Intact | PTEN loss = adverse prognostic marker; associated with higher stage and worse biochemical recurrence; combined PTEN loss + ERG positive = more aggressive phenotype |
Active surveillance (AS) avoids immediate radical treatment in men with low-risk prostate cancer, monitoring instead with serial PSA, digital rectal examination, and repeat biopsies. Pathological eligibility criteria vary between protocols, but the most widely used (PRIAS, CANARY, Johns Hopkins) typically require:
The world's foremost prostate pathologist. Chair of the ISUP 2005 and 2014 Modified Gleason Grading consensus conferences; creator of the Grade Group system; author of the definitive textbook Biopsy Interpretation of the Prostate (Wolters Kluwer, 7th edition). His criteria for EPE, SVI, and IDC-P are the global standard.
Chair of the ISUP 2019 Grading Consensus Conference; leading authority on Gleason grading reproducibility, digital pathology in prostate grading, and AI-assisted prostate cancer detection. Instrumental in European validation of Grade Groups and WHO 2022 prostate tumour classification.
Leading prostate pathologist in Australasia; key contributor to ISUP 2014 and 2019 Gleason consensus; expert on cribriform pattern prognostic significance, intraductal carcinoma, and the ISUP prostate pathology series publications. Chair of multiple RCPA pathology committee initiatives.
Prostate cancer biomarker expert; research on ERG fusion IHC as a diagnostic and prognostic tool; PTEN deletion IHC standardisation; contributor to ISUP prostate grading consensus and Canadian prostate cancer pathology guidelines.
Expert in genitourinary pathology — prostate, kidney, bladder, and testis. Author of Tumors of the Prostate Gland, Seminal Vesicles, Male Urethra, and Penis (AFIP Atlas of Tumor Pathology). Contributor to WHO genitourinary tumour classification and CAP prostate cancer reporting protocols.
Editor-in-chief of AJCC Cancer Staging Manual (8th edition); leading genitourinary pathologist with expertise in prostate, bladder, and kidney tumour staging. Contributor to WHO genitourinary tumours classification and CAP cancer protocols for GU pathology.