Foamy gland carcinoma in core needle biopsies of the prostate: clinicopathologic and immunohistochemical study of 56 cases ☆ Sevim Baykal Koca, MD a , Pelin Yıldız, MD b , Kemal Behzatoğlu, MD a, ⁎ a Department of Pathology, Istanbul Education and Research Hospital, Istanbul, Turkey b Department of Pathology, Bezmialem University, Medical Faculty, İstanbul, Turkey abstract article info Keywords: Prostate Adenocarcinoma Foamy gland Incidence Peripheral nerve invasion Foamy gland carcinoma is a subtype of acinar adenocarcinoma characterized by foamy appearance, large cytoplasm, pyknotic nuclei, inconspicuous nucleoli and infiltrative pattern. In this study, we investigated the histological features and the incidence of foamy gland carcinoma. We compared foamy gland carcinoma with acinar adenocarcinoma according to age, prostate-specific antigen value, Gleason score, peripheral nerve invasion and accompanying high-grade prostatic intraepithelial neoplasia. Besides, we investigated the diagnostic value of immunohistochemical markers in foamy gland carcinoma. A total of 863 TRUS-guided prostate needle core biopsies performed at our hospital pathology clinic between January 1, 2010, and December 31, 2011, were examined, 251 of these were diagnosed acinar type adenocarcinoma. Conventional acinar type adenocarcinoma was present in 195 (78%) cases, and foamy gland carcinoma, in 56 cases (22%). We found that 11 (19%) of the 56 foamy gland carcinoma cases were pure and 45 (81%) cases were mixed with conventional acinar type adenocarcinoma. Single-core localization was present in 7 of 14 pure foamy gland carcinomas, and the number of cases with a Gleason score of 7 and above was 21 (37%). No statistically significant difference was found between foamy gland carcinoma and conventional acinar type adenocar- cinoma in terms of age, Gleason score, high-grade prostatic intraepithelial neoplasia, and prostate-specific antigen values. Peripheral nerve invasion was found to be statistically significantly more common in foamy gland carcinoma compared to acinar type adenocarcinoma (P b .05). The staining percentage of immunohistochemical markers in foamy gland carcinoma was 90.1% for p63, 90.6% for 34Beta12 and 90.6% for AMACR. © 2014 Elsevier Inc. All rights reserved. 1. Introduction Prostate cancer is the most common type of cancer in men and ranks second in cancer deaths [1]. Its incidence has been increasing and the age at detection decreasing with the increase of diagnostic methods, use of prostate-specific antigen (PSA) among the routine controls of those over the age of 50 in particular, and increased awareness of prostate cancer. Most prostate adenocarcinoma cases are conventional acinar type adenocarcinoma. Although less common, there are also many subtypes of prostatic adenocarcinoma. Foamy gland carcinoma was first defined by Epstein and Nelson in 1996 and is one of the subtypes that cause the most difficulty during diagnosis [2]. Foamy gland adenocarcinoma is a subtype of acinar type prostatic adenocarcinoma and consists of cells with abundant foamy cytoplasm and a very low nucleus/cytoplasm ratio. It is more difficult to diagnose because it has a low histological grade and resembles the normal prostate glands in small tumors. There are few studies on foamy gland adenocarcinoma and although there is no difference with conventional acinar type adenocarcinoma in prognostic terms, a Gleason score of 7 has been reported to be more frequent in recent studies [3,4]. The large nuclei, prominent nucleoli and prominent infiltrative pattern that are the typical histological characteristics of classic acinar adenocarcinoma are not usually found in foamy gland carcinoma. This makes it difficult to identify these lesions in needle core biopsy materials especially when they are well differentiated. Immunohis- tochemical markers are therefore needed in the diagnosis of pure foamy gland carcinoma especially when there is only a small number of glands in only a few cores. We compared the frequency of the foamy cell variant and diagnostic problems of the cases diagnosed with prostate acinar type adenocarcinoma in all transrectal ultrasound (TRUS) biopsy of the prostate materials sent to the pathology laboratory of our hospital between 2010 and 2011 and compared these cases with the conventional type acinar adenocarcinoma in terms of PSA, age, Annals of Diagnostic Pathology 18 (2014) 271–274 ☆ We have no relevant financial interest in the products or companies described in this article. No actual or potential conflicts of interest exist. ⁎ Corresponding author. Samatya cad. Istanbul Egitim Hastanesi, Patoloji Lab., Koca M Pasa, Fatih, Istanbul, Turkey. Tel.: +90 5055784122; fax: +90 212 589 32 35. E-mail addresses: bksevim@gmail.com (S.B. Koca), pelinyildiz@yahoo.com (P. Yıldız), kbehzatoglu@hotmail.com (K. Behzatoğlu). http://dx.doi.org/10.1016/j.anndiagpath.2014.07.002 1092-9134/© 2014 Elsevier Inc. All rights reserved. Contents lists available at ScienceDirect Annals of Diagnostic Pathology