New Frontiers in Pathology GU case presentation Rajal B. Shah, M.D. Associate Professor - Pathology and Urology

Case 13 A 65 year-old white American male with serum PSA of 4 ng/ml, underwent extended 12 core biopsies

34βE12 + p63

P504S

Summary of atypical findings Disorganized growth pattern Presence of some round and poorly formed small glands Micro nucleoli Lack of basal cell staining in some glands AMACR reactivity

Diagnosis Benign prostate parenchyma with focus of partial atrophy

Diagnosis of Limited Cancer in Prostate Biopsy: Critical Issues Recognize cancer and avoid under- diagnosis (false negative) Recognize cancer and avoid under- diagnosis (false negative) Recognize benign mimics and avoid over-diagnosis (false positive) Recognize benign mimics and avoid over-diagnosis (false positive)

Pattern 2 Cribriform/large growth pattern Pattern 1 Small glandular growth pattern Pattern 3 Fused gland/solid growth pattern Mimics of Prostate Cancer

Pattern 1-Small gland mimics Seminal vesicle/ejaculatory duct epithelium Cowpers glands Verumontenum hyperplasia Crowding of small glands Mucinous metaplasia Mesonephric gland hyperplasia Post atrophic hyperplasia/atrophy Partial atrophy Adenosis Radiation atypia Nephrogenic adenoma Basal cell hyperplasia

PA: Among the most common reasons for second opinion Herawi M et al, AJSP, 2005

Partial atrophy (PA) - Background Experts have utiized various terms to describe partial atrophy Some have used the term post atrophic hyperplasia (PAH) to describe similar lesions (Amin MB et al, 1999, Srigley JR et al, 2004) Recently PA and PAH recognized as a distinct types of focal atrophy in the Working Group Classification of Focal Prostate Atrophy Lesions (De Marzo et al, 2006)

Partial atrophy - Significance Potential for confusion with prostatic adenocarcinoma (PCa) –Among the most common reasons for second opinion in a consultation practice (Herawi et al, 2005) –Potential immunohistochemical (basal cell markers and P504S (monoclonal antibody to AMACR)) overlap with PCa Association with inflammation and proliferation found in certain forms of atrophy such as post atrophic hyperplasia (Ruska et al, 1998; De Marzo et al, 1999; Shah R et al, 2001)

Architectural indices –Gland size –Gland shape –Circumscription –Stromal characteristics –Associated completely atrophic glands within the focus –Luminal secretions –Inflammation Cytological indices –Character of cytoplasm –Nuclear size in relation to benign glands –Micronucleoli (visible only at 40x) and macronucleoli (visible easily at 10X) AJSP, 32(1), 2008

Basal cell marker cocktail(34βE12 + p63) –Completely positive –Patchy positive –Completely negative P504S - Rabbit monoclonal antibody to AMACR (Zeta corporation, Sierra Madre, CA ) –Negative –Weak –Moderate-to-strong (Expression evaluated in relation to benign glands) AJSP, 32(1), 2008

Study design - Proliferation status Ki-67 (MIB-1 clone) immunohistochemistry Quantitative analysis by ChromaVision ACIS –Measurement of stain intensity of PA foci compared with benign glands (range 0-225, 0%-100%) –Manual delineation of foci

Results - Morphology (architectural features) N=73 foci

Circumscribed focus with stellate – star shaped glands

Disorganized poorly formed round glands

Results - Morphology (architectural features) % CASES FEATURES

Complete dark atrophic glands within the focus

Results - Morphology (cytologic features) % CASES FEATURES

Micro nucleoli visible at high power

Other benign conditions known to contain nucleoli: > Basal cell hyperplasia > Post atrophic hyperplasia > Adenosis > Radiation atypia > Benign glands associated with inflammation

Clear cytoplasm similar to adjacent benign glands, placed laterally to Nuclei giving them partially atrophic look

Results: IHC – Basal cell markers cocktail 34βE12 + p63

Other lesions with patchy/negative basal cell reactions PINAdenosis Lack of basal cell staining in few atypical glands is not necessarily diagnostic of cancer

Results: IHC – P504S

Comparison with published literature AMACR results AMACR results –79% (15/19 cases) (Herawi et al, 2005) Series consisting of selected consultation cases with AMACR staining performed at multiple institutions –31% (38/122 foci) (Adley et al, 2006) Hospital based series, AMACR staining using the triple antibody (P504S + CK 903+ p63)

AMACR-specificity issues PIN= Prostatic intraepithelial neoplasia, NA= Nephrogenic adenoma NS= Not studied

Results - Basal cell markers and P504S antibody as a panel Profile of Antibody Panel Number of foci (%) N=70 P504S(-)/basal cell markers(+) 58/70 (83%) P504S(+)/basal cell markers(+) 7/70 (10%) P504S(-)/basal cell markers(-) 5/70 (7%) P504S(+)/basal cell markers(-) 0/70 (0%)

Results - Proliferation status Results - Proliferation status N=54 foci Mean proliferative indices: –PA foci=5.5 (range 0-30) –Benign glands=5.6 (range 0-31) –P=0.97 (paired t-test)

Summary - Features that potentially mimic prostate cancer Morphology –Disorganized growth pattern –Small, round, poorly-formed glands –Visible nucleoli Immunohistochemistry –Very patchy/negative staining for basal cells –Possible AMACR positivity

Summary - Reliable morphologic features of PA Stellate/undulated gland lumina Pale cytoplasm similar to adjacent benign glands Presence of completely atrophic glands within the focus Lack of nuclear enlargement or macronucleoli

PAHPA PAH = post atrophic hyperplasia, PA = partial atrophy Morphological low-power comparison of PAH and PA

So where to draw a line between partial atrophy and atypia/cancer? Infiltrative glands Amphophilic cytoplasm Macronucleoli Presence of blue mucin Lack of basal cell markers and/or AMACR positivity with any of the above features

Architectural/cytological features not specific but suggest the benign diagnosis:

Architecture Lobular/circumscribed growth

Pseudo infiltrative appearance – patch like growth pattern

Benign glands as reference Similar cytoplasmic character Benign gland

Cellular spindle cell stroma BCH Adenosis Sclerosing adenosis

Nuclei occupy full cell height Complete atrophy BCH

Random cytological atypia SV Radiation atypia

Random cytological atypia, smudgy nuclei, prominent nucleoli, cytoplasmic vacuolization Radiation atypia

Conclusions A systemic approach using constellation of architectural and cytological features necessary to work up atypical small glandular proliferations Diagnosis relies on constellation of features Use markers to support your impression, use them as a panel An expert second opinion can help reduce atypia rate

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