Pseudoneoplastic Lesions and Mimickers of Carcinoma of the Prostate

Introduction

Classification of Pseudoneoplastic Lesions

1. Glandular mimickers (benign glands mistaken for cancer)
2. Reactive/proliferative lesions
3. Partial atrophy and its variants
4. Metaplastic lesions
5. Miscellaneous stromal and other lesions

1. Adenosis (Atypical Adenomatous Hyperplasia)

• Crowded, back-to-back glandular architecture resembles low-grade (Gleason 3+3) adenocarcinoma
• Pale to clear cytoplasm
• Occasional small nucleoli may be present
• Luminal crystalloids may be seen (a feature also seen in cancer)

• Lobular architecture (cancer is infiltrative)
• Basal cells present - patchy but identifiable by high-molecular-weight cytokeratin (HMWCK/34betaE12) or p63 IHC
• Nucleoli are inconspicuous (< 1 micron)
• No significant cytological atypia
• AMACR (alpha-methylacyl-CoA racemase / P504S) is negative or only focally weakly positive (unlike cancer where it is strongly and diffusely positive)

Smith and Tanagho's General Urology, 19th Edition - Basal cell layer absent in cancer, present in precursor/benign lesions, identifiable by HMWCK IHC.

2. Partial Atrophy

• Small, angulated glands with scant cytoplasm
• Infiltrative-appearing pattern between benign glands
• Nucleoli may be seen in some nuclei
• Basal cells are sparse and inconspicuous

• Glands have a typical "scalloped" or irregular luminal border
• Nuclear atypia is mild
• Basal cells present (at least focally) on HMWCK or p63
• AMACR negative
• Cytoplasm is scant and pale - unlike cancer which typically has more cytoplasm

3. Simple Atrophy and Cystic Atrophy

4. High-Grade Prostatic Intraepithelial Neoplasia (HGPIN)

• Prominent nucleoli (> 1 micron) identical to invasive carcinoma
• May have micropapillary or cribriform intraluminal projections
• AMACR is positive in ~20% of HGPIN cases
• Can be difficult to distinguish from intraductal carcinoma

• Architecturally intact duct outlines
• Basal cell layer is preserved (identifiable by p63 and HMWCK) - this is the single most important feature
• No true infiltration between stroma
• Lacks the desmoplastic stromal response of carcinoma

HGPIN incidence on biopsy averages 4-5%. Mean risk for cancer on subsequent biopsy is 20-30%. - Campbell Walsh Wein Urology

5. Atypical Small Acinar Proliferation (ASAP)

• Found in ~5% of biopsies
• Risk of carcinoma on repeat biopsy: ~40-50% (higher than HGPIN)
• Mandates repeat biopsy
• Represents a sampling artifact more than a distinct entity

6. Sclerosing Adenosis

• Small, closely packed glands
• Cellular stroma may suggest stromal invasion
• Intraluminal eosinophilic secretions and crystalloids may be present
• Some degree of nuclear atypia

• Basal cells are present and often prominent
• The spindle cell stroma is distinctive
• IHC: basal cells positive for p63, HMWCK, and also S-100 (unique feature - helpful clue)
• AMACR usually negative

7. Nephrogenic Adenoma (Nephrogenic Metaplasia)

• Small tubules and acini with hobnail cells
• Infiltrative pattern within the lamina propria
• Prominent nucleoli in some cells
• Clear cytoplasm
• Can be mistaken for clear cell carcinoma or prostatic adenocarcinoma

• Location: periurethral, not in peripheral zone
• IHC: PAX-8 positive (renal origin marker - key diagnostic feature)
• PSA and PSAP negative (unlike prostate cancer which is PSA/PSAP positive)
• p63 variably positive; AMACR can be focally positive (a pitfall)
• CK7 positive

8. Seminal Vesicle / Ejaculatory Duct Epithelium

• Large, hyperchromatic nuclei with prominent nucleoli
• May be sampled inadvertently on needle biopsy
• Lipofuscin pigment may not always be prominent

• Lipofuscin (golden-brown) cytoplasmic pigment - pathognomonic of seminal vesicle epithelium
• Marked nuclear pleomorphism (degenerative atypia) - "smudged" chromatin
• Low mitotic activity
• IHC: PSA and PSAP negative (seminal vesicle lacks PSA)
• MUC6 positive (seminal vesicle specific)
• Architecture: glands with complex papillary infoldings

9. Cowper's Glands (Bulbourethral Gland Tissue)

• Small, mucin-secreting glands with bland nuclei
• Can appear infiltrative around nerve fibers (mimicking perineural invasion)
• May be encountered in biopsy of apex

• Distinctive mucinous (mucicarmine positive) cytoplasm
• Nuclei are small, round, and bland - no nucleoli
• Lobular architecture
• IHC: PSA and PSAP negative
• Mucicarmine and PAS positive

10. Mesonephric Remnants

• Tubules with intraluminal eosinophilic colloid-like material
• Infiltrative pattern
• Can mimic minimal adenocarcinoma

• Intraluminal dense eosinophilic material (colloid-like)
• Bland nuclei, no nucleoli
• IHC: HMWCK positive (basal cells present)
• PSA negative, PAX-2/PAX-8 positive

11. Radiation Atypia

• Post-radiation prostate biopsies show cytological atypia with nuclear enlargement and prominent nucleoli
• Residual cancer must be distinguished from radiation-induced atypia

• Architectural pattern is preserved (maintains lobularity)
• Cytoplasmic vacuolization and smudged chromatin
• Basal cells may still be identifiable
• Wait at least 18-24 months post-radiation before interpreting biopsy as residual cancer
• IHC panel (PSA, AMACR, p63) can be helpful

12. Xanthoma (Foamy Gland Variant Differential)

13. Granulomatous Prostatitis

• On DRE: firm, indurated prostate
• Elevated PSA
• Histologically: epithelioid histiocytes may suggest carcinoma

• Granulomatous inflammation with multinucleated giant cells
• Clinical context (BCG therapy, TB, fungal infection)
• IHC: CD68 positive (histiocytes)

14. Clear Cell Cribriform Hyperplasia

• Cribriform pattern of glands identical to cribriform adenocarcinoma (Gleason 4)

• Clear cell cytoplasm
• Located in transition zone (central gland)
• Basal cells prominently present
• AMACR negative

Immunohistochemical Panel for Differential Diagnosis

Key Architectural and Cytological Clues

• Infiltrative glands between benign glands ("between and between" sign)
• Absence of basal cell layer
• Prominent nucleoli (> 1 micron, visible at 10x)
• Intraluminal blue mucin
• Intraluminal crystalloids (pink rhomboid crystals) - also seen in some benign lesions
• Perineural invasion
• Intraluminal pink amorphous secretions
• Glomeruloid structures
• Collagenous micronodules

• Lobular arrangement
• Basal cell layer present
• Lipofuscin pigment (seminal vesicle)
• Mucinous cytoplasm with no nucleoli (Cowper's glands)
• PAX-8 positivity (nephrogenic adenoma)

Summary Table

Clinical Importance

1. Misdiagnosis of benign mimickers as carcinoma leads to unnecessary radical prostatectomy, radiation, or hormonal therapy with major morbidity.
2. Misdiagnosis of true carcinoma as a benign mimicker leads to delayed treatment.
3. IHC (AMACR + p63 + HMWCK "triple cocktail") is the standard approach when morphology is equivocal.
4. ASAP on biopsy mandates repeat biopsy within 3-6 months.
5. HGPIN on multiple cores (>/= 2) carries similar cancer risk to ASAP.

Laboratory Investigations for Diagnosis of Bladder Cancer

1. Urinalysis (Routine)

• Pyuria - from concomitant infection or tumor necrosis
• Azotemia - if the tumor causes ureteral obstruction
• Anemia - from chronic blood loss or bone marrow replacement in metastatic disease

Smith and Tanagho's General Urology, 19th Edition - "The most common laboratory abnormality is hematuria."

2. Urine Cytology

• Sensitivity: 31-62% (overall); better for high-grade tumors
• Specificity: 94-100% (highly specific)
• High-grade tumors and carcinoma in situ (CIS) - most reliably detected
• Low-grade tumors - relatively insensitive (low cell shedding)

Campbell Walsh Wein Urology - Sensitivity 31-62%, specificity 94-100%. Paris classification standardizes reporting.

3. Urine-Based Biomarkers

A. Bladder Tumor Antigen (BTA) Tests

• BTA-STAT: Qualitative, point-of-care. Detects human complement factor H-related protein in urine.
• BTA-TRAK: Quantitative ELISA assay.
• More sensitive than cytology, especially for low-grade tumors, but less specific
• False positives: Active UTI, recent instrumentation, intravesical therapy - all limit reliability

B. Nuclear Matrix Protein 22 (NMP22)

• NMP22 is a nuclear structural protein elevated 20 times more in malignant than normal urothelial cells
• NMP22 Lab Test: Quantitative immunoassay - Sensitivity 69%, Specificity 77%
• NMP22 BladderChek: Point-of-care qualitative test - Sensitivity 58%, Specificity 88%
• More sensitive than cytology for low-grade tumors; equivalent for high-grade
• False positives: UTI, calculi, other urologic conditions

C. UroVysion FISH (Fluorescence In Situ Hybridization)

• Detects chromosomal abnormalities in exfoliated urothelial cells: aneuploidy of chromosomes 3, 7, 17 and homozygous deletion of 9p21 locus
• Positive if: ≥ 5 cells with gains of 2+ chromosomes, OR ≥ 10 cells with single chromosome gain, OR > 20% cells with 9p21 deletion
• Sensitivity: 63%, Specificity: 87%
• Unique advantage: Can be used to adjudicate equivocal cytology and to monitor patients after intravesical chemotherapy

D. ImmunoCyt Test

• Combines cytology with immunofluorescence using antibodies against mucin and CEA expressed on bladder cancer cells
• Improves sensitivity of cytology for low-grade tumors
• Used as an adjunct to, not replacement for, cytology

E. CxBladder Test

• Detects specific mRNA in urine (IGFBP5, HOXA13, MDK, CDK1, CXCR2)
• Uses a mathematical model incorporating patient-specific characteristics
• Geared toward ruling out bladder cancer in hematuria evaluation

F. Newer Tests

• AssureMDx: DNA methylation-based urine test
• Xpert Bladder Cancer Monitor: Detects TERT promoter mutations and FGFR3 mutations
• Designed to rule out cancer in surveillance/hematuria evaluation

1. Further evaluation of atypical urine cytology
2. Assessment of response to intravesical therapy

Smith and Tanagho's General Urology, 19th Edition; Campbell Walsh Wein Urology

4. Summary Comparison Table

Key Points

• Urine cytology remains the gold standard urine-based test - high specificity makes a positive result highly meaningful
• No urine test replaces cystoscopy + biopsy, which is the definitive diagnostic method
• Low-grade tumors shed fewer abnormal cells - sensitivity of all urine tests is poor for these
• FISH is particularly useful when cytology is atypical or equivocal
• Multiple consecutive urine samples improve cytology yield
• Negative urine cytology cannot rule out bladder cancer

Role of Testicular Biopsy in Male Infertility - From a Pathology Perspective

Introduction

Campbell Walsh Wein Urology - "Testis biopsy is not indicated in the initial diagnostic evaluation of the infertile man" as FSH + testis size can predict obstruction vs spermatogenic failure in most cases. It is reserved for specific indications.

Indications for Testicular Biopsy

Diagnostic Indications

1. Azoospermia - to distinguish obstructive from non-obstructive causes when FSH and testis size are equivocal
2. Confirmation of spermatogenic failure before reconstructive surgery
3. Evaluation of unexplained infertility with severe oligospermia
4. Suspected intratubular germ cell neoplasia (ITGCN) in cryptorchidism, intersex disorders, or contralateral testis after germ cell tumor

Therapeutic Indications

1. Sperm retrieval for IVF/ICSI in obstructive and non-obstructive azoospermia - testicular sperm extraction (TESE) or micro-TESE

Fixation - Critically Important

Campbell Walsh Wein Urology - "Formalin fixation results in distortion of testicular histology and should not be used for testis biopsy."

Histological Patterns on Testicular Biopsy

1. Normal Spermatogenesis

• All stages of spermatogenesis present: spermatogonia → primary spermatocytes → secondary spermatocytes → spermatids → spermatozoa
• Tubules of normal diameter
• Leydig cells normal
• Interpretation: Obstruction is the cause of azoospermia - evaluate ductal system (vasography, epididymal assessment)
• Best prognosis for sperm retrieval

2. Hypospermatogenesis

• All stages of spermatogenesis present but quantitatively reduced
• Fewer germ cells at each stage; reduced sperm output
• Tubular diameter may be slightly reduced
• Interstitial and Sertoli cells relatively preserved
• Interpretation: Non-obstructive azoospermia or severe oligospermia; sperm retrieval (TESE) has a reasonable success rate

3. Maturation Arrest (Spermatogenic Arrest)

• Spermatogenesis halted at a specific developmental stage
• Early arrest: Arrest at primary spermatocyte level - no secondary spermatocytes or spermatids
• Late arrest: Arrest at spermatid level - round spermatids present but no elongated spermatids/spermatozoa
• Tubular diameter preserved
• Sertoli cells present; Leydig cells may be normal
• Genetic association: AZFb deletions on Y chromosome cause arrest at primary spermatocyte stage; AZFa deletions may cause Sertoli cell-only pattern
• Prognosis: TESE success rate approximately 40% (especially late arrest)

4. Sertoli Cell-Only Syndrome (Germ Cell Aplasia / Del Castillo Syndrome)

• Complete absence of germ cells from seminiferous tubules
• Only Sertoli cells line the tubular epithelium
• Tubules are smaller in diameter, may appear empty
• Peritubular fibrosis may be present
• Leydig cells are present and may appear hyperplastic
• Interstitium and basement membrane relatively intact
• Causes: Genetic (AZFa, AZFb deletions, Klinefelter syndrome), irradiation, chemotherapy, cryptorchidism, viral orchitis, idiopathic
• Prognosis: TESE success rate approximately 30%
• Micro-TESE may find isolated foci of spermatogenesis despite Sertoli cell-only appearance on standard biopsy (due to focal heterogeneity of spermatogenesis)

5. Tubular Sclerosis / Tubular Atrophy

• Seminiferous tubules replaced by hyaline, collagenous material (peritubular/intratubular fibrosis)
• Germ cells and Sertoli cells absent
• Tubular "ghost" outlines with thickened basement membrane
• Leydig cells may appear prominent (relative hyperplasia)
• Causes: End-stage testicular atrophy, post-orchitis, post-torsion, radiation damage
• Prognosis: Poorest - TESE usually unsuccessful; sperm retrieval nearly impossible

Additional Histological Finding: Intratubular Germ Cell Neoplasia (ITGCN)

• Also called carcinoma in situ of testis
• Large atypical germ cells with clear cytoplasm and irregular nuclei lining the basement membrane of seminiferous tubules
• Spermatogenesis absent in affected tubules
• Markers: PLAP (placental alkaline phosphatase), OCT3/4, c-Kit positive on IHC
• Found in contralateral testis in ~5% of germ cell tumor patients, in cryptorchidism, and intersex
• Testicular biopsy of contralateral testis is indicated in high-risk patients to detect ITGCN

Heterogeneity of Spermatogenesis - A Key Pathology Concept

• One-third of men with a Sertoli cell-only biopsy were found to have sperm at a distant site in the same testis
• ~40% of men with 1-2 prior negative biopsies had mature sperm found at micro-TESE
• Even with 3-4 negative prior biopsies, 1 in 9 men had mature sperm on micro-TESE

Campbell Walsh Wein Urology - "Spermatogenesis may be highly focal in men with azoospermia, and a biopsy may not describe the entirety of the histology of a testis."

Micro-TESE Sperm Retrieval Rates by Histological Diagnosis

Campbell Walsh Wein Urology, Table 67.5

Summary: Pathological Role in Management Algorithm

Azoospermia
    │
    ├── FSH markedly elevated + small testes
    │       → Likely non-obstructive (spermatogenic failure)
    │       → Biopsy / Micro-TESE to retrieve sperm + histological pattern
    │
    ├── FSH normal + normal testis size
    │       → Likely obstructive
    │       → Biopsy confirms normal spermatogenesis → Vasography + reconstruction
    │
    └── Equivocal
            → Biopsy clarifies pattern

• Normal spermatogenesis → Surgical reconstruction of obstruction
• Hypospermatogenesis / Maturation arrest / Sertoli cell-only → TESE/micro-TESE for IVF/ICSI
• ITGCN found → Surveillance / irradiation of testis
• Tubular sclerosis → Donor sperm / adoption counseling

Prognostic Markers in Prostatic Carcinoma - Pathology Perspective

Introduction

A. HISTOLOGICAL GRADE - The Most Important Pathological Prognostic Marker

1. Gleason Grading System

• Range: 6 to 10 (scores 2-5 are no longer assigned in practice)
• Tertiary pattern: If a higher-grade tertiary pattern 5 is present, it is incorporated - a 3+4 with tertiary 5 becomes 3+5

Campbell Walsh Wein Urology - "Histologic grade is the most important information obtained from prostate needle biopsy."

2. ISUP Grade Groups (2014 / WHO 2016 Classification)

• GG 1 (Gleason 3+3=6) has virtually no metastatic potential - supports active surveillance
• The distinction between GG2 (3+4) and GG3 (4+3) is prognostically significant despite both being "score 7"
• Grade Group accurately predicts biochemical recurrence after radical prostatectomy

Campbell Walsh Wein Urology - "The new system simplifies grading, appropriately classifies the lowest risk as Grade Group 1, and accurately predicts prognosis."

• Gleason grade should NOT be assigned to carcinomas with hormone therapy effect (grade appears artifactually higher)
• Post-radiation: cancer showing treatment effect is NOT graded and carries equivalent prognosis to a non-cancerous diagnosis
• Post-cryotherapy/HIFU: if residual cancer has no treatment effect, Gleason score can be assigned

B. BIOPSY-DERIVED PROGNOSTIC PARAMETERS

3. Number and Percentage of Positive Cores

• More positive cores and higher percentage positive correlate with:
  • Higher tumor volume
  • Extraprostatic extension at radical prostatectomy
  • Worse biochemical recurrence-free survival
• Used in nomograms (Partin tables, CAPRA score) to predict pathological stage

4. Perineural Invasion (PNI) on Biopsy

• Cancer cells infiltrating around and along nerve fibers
• Prognostic significance: Associated with extraprostatic extension (nerves provide a path of least resistance for spread beyond the capsule)
• Guides nerve-sparing decisions during radical prostatectomy
• Presence on biopsy is used in active surveillance candidacy assessment

5. Seminal Vesicle Invasion on Biopsy

• Sampling of seminal vesicle involvement during biopsy
• Indicates locally advanced (pT3b) disease
• Associated with significantly poorer prognosis - higher risk of nodal and distant metastasis

6. Periprostatic Fat Involvement on Biopsy

• Tumor in periprostatic adipose tissue = extraprostatic extension
• Adverse prognostic finding indicating locally advanced disease

Campbell Walsh Wein Urology - "Findings of seminal vesicle invasion or involvement of the periprostatic fat on prostate needle biopsy are associated with poorer prognosis."

C. RADICAL PROSTATECTOMY SPECIMEN - Pathological Stage Markers

7. Pathological Stage (pTNM)

8. Surgical Margin Status

• Positive surgical margin (PSM): Ink touches tumor at cut edge of specimen
• Indicates residual tumor left behind - predicts biochemical recurrence
• Location matters: apical positive margins have better prognosis than posterior/posterolateral margins
• Graded as focal vs. extensive positive margin

9. Seminal Vesicle Invasion (SVI)

• Tumor in the muscular wall of seminal vesicle = pT3b
• Strong predictor of systemic disease and poor prognosis
• Associated with high rate of lymph node metastasis

10. Lymphovascular Invasion (LVI)

• Tumor emboli within lymphatic or vascular channels
• Predicts lymph node metastasis and distant recurrence
• Independent adverse prognostic factor

11. Lymph Node Status (pN)

• Nodal involvement = systemic disease
• Number of positive nodes and extent of involvement matter
• pN1 disease has significantly worse 10-year cancer-specific survival

D. TUMOR VOLUME AND EXTENT

12. Tumor Volume

• Larger tumor volume correlates with higher stage and worse prognosis
• Assessed as percentage of gland involved or cm³ on RP specimen
• Dominant nodule size > 0.5 mL has greater metastatic potential
• Used in combination with grade for risk stratification

13. Intraductal Carcinoma of the Prostate (IDC-P)

• Malignant cells filling and expanding prostatic ducts/acini
• Associated with high-grade, high-volume cancer
• Presence on biopsy - adverse prognostic marker even when invasive carcinoma is absent
• Predicts worse pathological stage at RP

E. HISTOLOGICAL SUBTYPES - Prognostic Significance

Campbell Walsh Wein Urology - "The average survival of patients with small cell carcinoma of the prostate is less than 1 year." Small cell carcinomas are not assigned a Gleason grade.

F. BIOCHEMICAL / CLINICAL MARKERS (Used Alongside Pathology)

14. Serum PSA (Prostate-Specific Antigen)

• Pre-treatment PSA level is a strong independent prognostic factor
• Integrated with pathological grade in AJCC staging (8th ed.) and risk stratification
• PSA density (PSA / prostate volume) adds predictive value
• Post-treatment PSA kinetics: PSA doubling time (PSADT) and PSA velocity predict recurrence

15. PSMA (Prostate-Specific Membrane Antigen)

• Overexpressed in higher-grade and metastatic prostate cancer
• Basis for PSMA-PET/CT imaging and PSMA-targeted therapies
• High PSMA expression correlates with worse prognosis

G. MOLECULAR / IHC PROGNOSTIC MARKERS

H. INTEGRATED RISK STRATIFICATION

• Low risk: PSA ≤ 10, GG1, stage ≤ cT2a
• Intermediate risk: PSA 10-20, GG2-3, stage cT2b
• High risk: PSA > 20, GG4-5, stage ≥ cT2c

Summary Table of Key Pathological Prognostic Markers