Case Report
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Oncol. Jun 10, 2017; 8(3): 289-292
Published online Jun 10, 2017. doi: 10.5306/wjco.v8.i3.289
Prostatic adenocarcinoma oncocytic variant: Case report and literature review
Matthew M Klairmont, Nadeem Zafar
Matthew M Klairmont, Nadeem Zafar, Department of Pathology, University of Tennessee Health Science Center, Memphis, TN 38163, United States
Author contributions: All authors contributed to the acquisition of data, writing, and revision of this manuscript.
Institutional review board statement: This case report was exempt from the Institutional Review Board standards at University of Tennessee Health Science Center at Memphis.
Informed consent statement: The patient reported in this study gave verbal informed consent authorizing use and disclosure of his protected health information.
Conflict-of-interest statement: There are no conflicts of interest to report for any author.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Nadeem Zafar, MD, Associate Professor, Department of Pathology, University of Tennessee Health Science Center, 930 Madison 5th Floor, Memphis, TN 38163, United States. nzafar@uthsc.edu
Telephone: +1-901-4486436 Fax: +1-901-4486979
Received: January 29, 2017
Peer-review started: February 12, 2017
First decision: March 8, 2017
Revised: March 29, 2017
Accepted: April 23, 2017
Article in press: April 24, 2017
Published online: June 10, 2017
Processing time: 124 Days and 4 Hours
Abstract

The oncocytic variant of prostatic adenocarcinoma is exceptionally rare with only 4 cases reported in the English literature. Little is known about the clinical behavior of this variant of prostatic adenocarcinoma, because of the exceptionally low number of reported cases. The 2016 World Health Organization Classification of Tumors of Prostate does not recognize the oncocytic variant, again likely related to the exceptional paucity of reported cases. Here, we report the fifth case of the oncocytic variant of acinar type prostatic adenocarcinoma in an asymptomatic 64-year-old Caucasian American male with elevated serum prostate specific antigen (7.33 ng/mL; normal range 0-4.00 ng/mL) during routine blood screening for diabetes mellitus. At subsequent transrectal prostate biopsy, the right side of prostate was infiltrated by adenocarcinoma with tumor cells forming variably differentiated glands, including some poorly differentiated. Tumor cell nuclear:cytoplasmic ratio was low, with small to intermediate sized vesicular nuclei and only rare discernable small nucleoli. Cellular cytoplasm was characteristically granular pink with sharply defined cell membranes. Positive AMACR (P504S) epithelial immunohistochemical staining and absence of staining for prostatic basal cells confirmed the tumor to be primary prostatic adenocarcinoma. AMACR immunohistochemical staining was also helpful with accurate grading of the tumor due to the difficulty of differentiating tumor cells from residual prostate myocytes at routine hematoxylin and eosin (HE) staining. This new case adds to the exceptionally small number of previously reported cases of the oncocytic variant of primary prostatic adenocarcinoma. It also highlights the difficulty associated with Gleason scoring of the oncocytic variant by routine HE evaluation and the usefulness of AMACR (P504S) immunostaining for accurate grading of prostatic adenocarcinoma in the oncocytic variant.

Keywords: Prostate; Adenocarcinoma; Clinical behavior; Oncocytic; Gleason; Prognosis

Core tip: The oncocytic variant of prostatic adenocarcinoma is exceptionally rare with only 4 cases reported so far. Through reporting this new case, the oncocytic variant is being highlighted and challenges associated with its accurate diagnosis and staging discussed. The use of immunohistochemistry to confirm prostatic origin of this tumor for accurate grading of this lesion is also highlighted. It is also postulated that the tumor cells may be difficult to locate for their presence and organization at hematoxylin and eosin evaluation, potentially resulting in inaccurate grading of the tumor, the tumor likely behaves no different from the usual/typical variant of acinar-type adenocarcinoma if appropriately graded.