2 May 2008 Case of the Week #117


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We thank Debra L. Zynger, M.D., Ava Hosseini, B.A. and Ximing J. Yang, M.D., Ph.D., Northwestern Memorial Hospital, Northwestern University, Chicago, Illinois (USA) for contributing this case.  To contribute a Case of the Week, email NatPernick@Hotmail.com with the clinical history, your diagnosis and microscopic images in JPG, GIF or TIFF format (send as attachments, we will shrink if necessary). Please include any other images (gross, immunostains, etc.) that may be helpful or interesting. We will write the discussion (unless you want to), list you as the contributor, and send you $35 (US dollars) for your time after we send out the case. Please only send cases with high quality images and a diagnosis that is somewhat unusual (or a case with unusual features).


Case of the Week #117


Clinical History


A 70 year old man had laparoscopic robotic-assisted radical prostatectomy.


Micro images: low power; high power #1; #2; #3


What is your diagnosis?




























Pseudohyperplastic variant of prostatic adenocarcinoma




The malignant nature of the hyperplastic appearing glands was confirmed with the triple stain, which showed lack of basal cells (i.e. no staining) by p63 and high molecular weight keratin, and staining of the hyperplastic cells by AMACR: triple stain #1 (AMACR, p63, HMWK); #2. The normal appearing glands served as controls.


Pseudohyperplastic variant of prostatic adenocarcinoma is a rare variant in which at least 60% of the tumor has architectural features resembling benign hyperplastic glands (AJSP 2000;24:1039). The tumor typically has complex, medium to large sized glands with crowding, papillary infoldings and branching or cystic dilatations. The nuclei are enlarged, and often have prominent nucleoli. There are usually pink amorphous secretions, and often crystalloids. At low power, transition to typical, small acinar adenocarcinomas may be a helpful diagnostic clue (AJSP 1998;22:1239). With core needle biopsies, the only diagnostic clue may be a subtle disruption of the normal glandular - stromal relationship. Basal cell stains (p63, HMWK) are important to confirm the absence of basal cells, and the tumor cells are immunoreactive for AMACR / P504S in 70% of cases (AJSP 2003;27:772).


Pseudohyperplastic variant may be misdiagnosed as benign hyperplasia. In one study, the rate of false negative diagnoses was 1.3% for TURP specimens (Pathol Oncol Res 2003;9:232). The differential diagnosis also includes high grade prostatic intraepithelial neoplasia. Although high grade PIN also shows papillary infoldings with prominent nucleoli, the glands are not as crowded or infiltrative.



Nat Pernick, M.D., President
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