[982] Atypical Adenomatous Hyperplasia (AAH) That Is Associated with Prostatic Adenocarcinoma Has Higher Expression of α-Methylacyl Coenzyme A Racemase (AMACR) Than AAH Not Associated with Cancer.

Chen Zhang, Gregory T MacLennan, Rodolfo Montironi, Antonio Lopez-Beltran, Yan Li, Puay-Hoon Tan, Kenneth A Iczkowski, Liang Cheng. Indiana University, Indianapolis; Case Western Reserve University, Cleveland, OH; Polytechnic University of the Marche Region, Ancona, Italy; Cordoba University, Spain; Amylin Pharmaceuticals Inc, San Diego, CA; Singapore General Hospital, Singapore; University of Colorado, Aurora

Background: Alpha-methylacyl coenzyme A racemase (AMACR) is highly expressed in prostatic adenocarcinoma. Atypical adenomatous hyperplasia (AAH) is a histologic mimicker of prostatic adenocarcinoma. A detailed analysis of AMACR expression in AAH and its association with prostatic adenocarcinoma (PCA) is lacking.
Design: One hundred twenty one AAH foci from 101 patients who underwent transurethral prostatic resection or prostatectomy were immunohistochemically analyzed for AMACR, keratin 34βE12, and p63 expression by a triple antibody (PIN-4) cocktail stain.
Results: Sixty-eight foci (56%) of AAH showed no AMACR immunostaining. Fourteen cases (12%) showed weak AMACR immunoreactivity in 1-9% of lesional cells. Sixteen cases (13%) showed strong immunopositivity for AMACR in >50% of lesional cells. AMACR expression in AAH was significantly higher in cases in which co-existing PCA was present, when compared with its expression in AAH foci without co-existing PCA (p=0.029). Strong diffuse P504S positivity in over 50% of lesional cells was seen almost exclusively in AAH foci with co-existing PCA (p=0.003). P504S expression in AAH showed no correlation with patient age (p=0.053), specimen type (p=0.053), prostate weight (p=0.32), zonal location (p=0.50), distance to cancer (p=0.16), Gleason score (p=0.38), or pathologic stage (p=0.23). Increased AMACR expression showed a negative correlation with the size of AAH foci (p=0.03). All AAH lesions showed fragmented basal cell layers, highlighted by p63 and high-molecular weight cytokeratin stainings.
Conclusions: A significant percentage of AAH cases show stronger and more extensive AMACR expression when associated with prostatic adenocarcinoma, as compared to AAH foci found without coexisting prostate cancer, providing additional evidence linking AAH to prostatic adenocarcinoma.
Category: Genitourinary (including renal tumors)

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 100, Monday Morning


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