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The Use of Immunohistochemistry in Prostate Needle Core Biopsies 2009 Current Issues in Anatomic Pathology May 30th San Francisco, CA

Uses of Immunohistochemistry

• Confirm your diagnosis of cancer – Histologically subtle patterns

• Work-up small atypical foci Jesse K McKenney, MD Director, Urologic Pathology

Overview • Histology lab decisions – Routine protocol

• • • •

Available immunostains Interpretation Real mimic of cancer Examples

The Technical Issues (What’s your protocol?)

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Preparing Slides for Immunohistochemistry

Unstained Interval Levels

1) No prophylactic measures -- Order stains on new levels from block -- De-stain H&E with atypical glands

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2) Saved unstained interval levels

Hameed and Humphrey Am J Clin Pathol 2009;131:683-688

Comparison of Methods Original H&E Routine Deeper

De/Re

Interval Levels

Technical Risk

Extra Work

Lose Focus

Extra Chances

• 682 prostate needle core cases – (n=38) Ordered stains on interval levels and recut levels – Loss of atypical focus • 3 interval (8%) • 19 recuts (50%)

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Unstained Interval Levels L1

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The Stains

Cytokeratin 34ßE12

Immunostains • Basal cell markers – Cytoplasmic • Cytokeratin 34ßE12 (CK903) • Cytokeratin 5/6

– Nuclear • p63

• AMACR/P504S

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p63

Cocktails

• p63/ CK 34ßE12 cocktail – Anecdotal cases of basal cell staining with one marker but not the other in individual cases

Basal Cell Markers: Summary • Sensitivity p63 > CK 34ßE12 • p63/ CK 34ßE12 cocktail – Better intensity – Better “quality” – Two for one

Interpreting Basal Cell Markers • The basal cell layer is often incomplete • Some benign prostate glands can be negative (5-23% in reported studies) • Rules that I follow: • Morphology driven staining • Patchy non-circumferential staining is sufficient evidence of benignity • A collection of suspicious glands should be interpreted as a whole

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Population of crowded glands: probable partial atrophy

Partial atrophy: population interpreted together

Entrapped benign glands with cancer

AMACR (P504S/Racemase) • Amino acid enzyme involved in fatty acid oxidation • Found to be selectively over-expressed in prostate cancer by gene microarray studies in 2000 • Antibodies to AMACR are available – Many good studies reporting sensitive marker of malignant prostate glands

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Prostate Cancer

AMACR/Racemase/P504S

AMACR Problems

Granular cytoplasmic Luminal/Apical Circumferential

AMACR/p63 cocktail Cytoplasmic AMACR staining in benign glands

• Immunoreactivity in benign glands – Benign, NOS (2-36%) – Atrophy (4-36%) – Partial atrophy (50%) – Adenosis (18%) – Nephrogenic adenoma (35-58%)

AMACR

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AMACR Problems

AMACR/p63 Cocktail

• Immunoreactivity in carcinoma – Overall (82-95%) – Pseudohyperplastic (70-77%) – Foamy (62-72%) – Atrophic (70%)

• Shown to be equivalent to using both antibodies separately • Advantage in focal lesions – Only one slide is needed

Hameed O, Sublett J, Humphrey PA. Am J Surg Pathol 2005;29:579-587

Most Common Problems • Benign (Pseudomalignant) – Partial atrophy

The Problematic Lesions

• Carcinoma (Pseudobenign) – Pseudohyperplastic carcinoma – Foamy carcinoma – Atrophic carcinoma

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Partial Atrophy

Partial Atrophy • Most common benign mimic of prostate cancer (Herawi et al. AJSP 2005;29;874-80) • Earliest phase of atrophy (nuclei more Partial atrophy can be the closest mimic spaced apart and less basophilic) of prostatic adenocarcinoma! • Variable loss of cytoplasm • Nucleoli may be present (15%) see it pale everyday. • Crowded We glands with cytoplasm and disorganized appearance Oppenheimer JR, Wills ML, Epstein JI. Partial atrophy in prostate needle cores: another diagnostic pitfall for the surgical pathologist. Am J Surg Pathol 1998;22:440-5

Partial Atrophy

Partial Atrophy

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Subtle Variants of Gleason Prostate Carcinoma (Pseudo-Benign)

Pseudohyperplastic Carcinoma

• Pseudohyperplastic • Foamy • Atrophic

Pseudohyperplastic CA

Normal Prostate

Pseudohyperplastic Carcinoma

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Pseudohyperplastic Carcinoma

Foamy Carcinoma

Foamy Carcinoma

Atrophic Carcinoma

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Atrophic Carcinoma Admixed with Conventional

Foamy/Atrophic Carcinoma

Using the Stains

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CK 34ßE12

My Diagnosis

• Benign prostatic glands and stroma

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AMACR/p63

My Diagnosis

• Prostatic adenocarcinoma, Gleason score 6 (3+3)

AMACR/Basal cell cocktail

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My Diagnosis

• Atypical small acinar proliferation, highly suspicious for carcinoma (S/C)

• Comment: There is a small gland proliferation present in biopsy “right apex” consisting of two glands with morphologic and immunohistochemical highly suspicious for carcinoma.

Goldstein NS, Begin LR, Grody WW, Novak JM, Qian J, Bostwick DG.

Minimal or no cancer in radical prostatectomy specimens. Report of 13 cases of the "vanishing cancer phenomenon".

Am J Surg Pathol 1995 Sep;19(9):1002-9

My Diagnosis

• Prostatic adenocarcinoma, Gleason score 6 (3+3)

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AMACR/Basal cell cocktail

My Diagnosis

• Prostatic adenocarcinoma, Gleason score 6 (3+3)

AMACR/p63/CK34BE12

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My Diagnosis

• Benign prostatic glands and stroma with radiation atypia

AMACR/Basal cell cocktail

My Diagnosis

• Atypical small acinar proliferation, highly suspicious for carcinoma (S/C)

• Comment: There is a small gland proliferation present in biopsy “left base” consisting of two glands with morphologic and immunohistochemical highly suspicious for carcinoma.

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Rule Out Pseudohyperplastic Carcinoma

Rule Out Pseudohyperplastic Carcinoma

My Diagnosis

• Benign prostatic glands and stroma

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Summary

Deciding on a Histology Protocol

• My approach – Rule out benign mimics – Know the “pseudo-benign” variants of cancer • Don’t rule out cancer for the wrong reason

– Use immunohistochemistry

• In my opinion, cutting and saving interval unstained slides is the best method – Retrospective and prospective studies

• Not blindly (specificity issue) • Confirmation – e.g., Pseudohyperplastic or foamy

• Rule out benign with a few atypical glands

Choosing Your Immunostains: Basal Cell Markers • • • •

p63 is most sensitive basal cell marker CK 34ßE12 is also acceptable CK 5/6 probably shouldn’t be used at present p63/ CK 34ßE12 cocktail is a good alternative

• How often do you use them in your practice?

Choosing Your Immunostains: Do you need AMACR? • Is AMACR standard of care? • Do you have dual chromagen capability? – AMACR/p63/HMWCK cocktail can be very useful – Does your case volume rationalize a stain only used in prostate biopsies?

– Is it cost effective to have one stain for prostate only? – CK 34ßE12 can also be used as your high molecular weight cytokeratin

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Using the Term ASAP • Not simply for “funny looking” glands • When benign lesions are excluded, ASAP identifies a group of patients whose pretherapy work-up and risk assessment will benefit from additional biopsies • Generally, should not use ASAP if any basal cells

The Use of Immunohistochemistry in Prostate Needle Core Biopsies

Jesse K McKenney, MD Director, Urologic Pathology Stanford University Medical Center

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