Detection of prostate cancer by alpha-methylacyl CoA racemase (P504S) in needle biopsy specimens previously reported as negative for malignancy

AIMS : To investigate the possibility of detecting small focal prostatic cancer by alpha-methylacyl CoA racemase (AMACR)/P504S immunohistochemistry on needle biopsy specimens that were previously interpreted as negative for carcinoma on routine haematoxylin and eosin (H&E)-stained sections. METHODS: Prostate needle biopsy specimens (n = 793) previously interpreted as benign prostatic tissue by conventional morphology from 239 patients with prostatic cancer diagnosed in other biopsy cores taken at the same biopsy session were stained with the P504S monoclonal antibody. If a biopsy specimen stained positively, two pathologists independently reviewed the original corresponding H&E-stained sections to establish the malignant diagnosis. RESULTS: Eighty-four of the 793 biopsy specimens showed AMACR immunoreactivity; nine of these (9/793, 1.1%) contained previously unrecognized small focal prostatic carcinoma (Gleason 6, N = 8; Gleason 8, N = 1). Six of nine (67%) carcinomas showed foamy/pseudohyperplastic (N = 3) or atrophic (N = 3) features. Additionally, five biopsy specimens (5/793, 0.6%) with positive AMACR staining that did not meet the criteria for prostatic cancer on the original H&E slides were considered to be atypia. CONCLUSIONS: In this study, we found a 1.1% false-negative rate for carcinoma on routine H&E-stained sections. AMACR immunohistochemical staining has shown the ability to improve detection of small focal prostatic carcinoma that could be missed by conventional histological examination.     

Paneth cell-like change in benign prostate can account for P504S (AMACR) reactivity

Paneth cell-like neuroendocrine metaplasia of benign and cancerous prostate was described in 1992. Here, we note that P504S (AMACR), the cytoplasmic marker for prostate cancer used alone or in concert with basal cell markers, can be strongly reactive in benign prostatic acini with Paneth cell-like change.     

Comparison of monoclonal antibody (P504S) and polyclonal antibody to alpha methylacyl-CoA racemase (AMACR) in the work-up of prostate cancer

AIM: Studies using a monoclonal (P504S) and a polyclonal antibody (p-AMACR) to alpha-methylacyl-CoA racemase (AMACR) have shown variable expression in prostate cancer (PCa). The goal is to compare the sensitivity of both antibodies in PCa and evaluate their utility in the work-up of atypical prostate needle biopsies (NBXs). METHODS AND RESULTS: A tissue microarray (TMA) with 248 samples of benign prostate, high-grade prostatic intraepithelial neoplasia (HGPIN) and PCa samples, 20 NBXs with minute PCa and 32 NBXs with 'atypical' foci were stained with P504S and p-AMACR. Ninety percent of PCa (76/76 TMA, 16/20 NBXs) showed predominantly strong p-AMACR expression while 87% (65/69 TMA, 16/20 NBXs) showed variable P504S expression (sensitivity 90% versus 87%, P = 0.10). In HGPIN, P504S and p-AMACR were positive in 77% and 91% of samples, respectively. In the 'atypical' NBXs group, 53% were classified as PCa, 12% benign and 35% atypical, suspicious for PCa, after review of the basal marker. Of atypical, suspicious for PCa, P504S/p-AMACR helped convert the diagnosis to PCa in 5/11 (45%) cases, where, despite negative basal cell markers, morphology was less than optimal. CONCLUSIONS: Differences between P504S and p-AMACR appear marginal and clinically insignificant. AMACR is negative in a subset of unequivocal minute PCa with both antibodies. However, when utilized in proper context, AMACR may offer significant advantage in converting an 'atypical' diagnosis to PCa where morphology and basal markers are less than optimal in resolving the diagnosis.     

Analysis of alpha-methylacyl-CoA racemase (P504S) expression in high-grade prostatic intraepithelial neoplasia

Alpha-methylacyl-CoA racemase (AMACR), also known as P504S, is a recently identified molecular marker for prostate cancer. The expression of AMACR/P504S has also been observed in high-grade prostatic intraepithelial neoplasia (PIN), a precursor lesion of prostate cancer. However, a detailed study focusing on the analysis of AMACR/P504S expression in high-grade PIN has not been performed. In this study, we analyzed AMACR/P504S expression by immunohistochemistry in 3954 prostatic ducts and acini with high-grade PIN from 140 prostatectomy specimens. AMACR/P504S immunoreactivity was measured as negative (0), weakly positive (+1), moderately positive (+2), and strongly positive (+3). AMACR/P504S immunoreactivity was detected in 90.0% (126/140) of high-grade PIN cases, although only 41.5% (1642/3954) of prostatic glands involved by PIN showed AMACR/P504S immunoreactivity. A significantly higher AMACR/P504S-positive rate (56.0%) was found in isolated high-grade PIN glands adjacent to cancer (distance less than 5 mm) compared with those away from cancer (distance more than 5 mm; 14%, P < 0.0001). High-grade PIN glands adjacent to cancer also showed a higher (P < 0.0004) AMACR/P504S intensity (1.62) than did those away from cancer (1.11). Our results suggest that PIN strongly positive for AMACR/P504S might be more closely associated with cancer than PIN negative or weakly positive for AMACR/P504S. This study provides additional evidence to link high-grade PIN as a precursor lesion to prostatic adenocarcinoma.     

The significance of the P504S expression pattern of high-grade prostatic intraepithelial neoplasia (HGPIN) with and without adenocarcinoma of the prostate in biopsy and radical prostatectomy specimens

Diagnosis of prostatic adenocarcinoma is usually not difficult in biopsy specimens. Problems may occur in biopsy specimens, containing only a few suspicious lesions. Recently, P504S has been tested as a new marker for prostatic carcinoma. When over-expressed in atypical glands without basal cells, it establishes the diagnosis of prostatic carcinoma. We analysed the staining intensity of P504S in 208 biopsy specimens from prostates (1) with adenocarcinoma (n=132), (2) with high-grade prostatic intraepithelial neoplasia (HGPIN) with adenocarcinoma (n=36), (3) with HGPIN alone (n=40) and in radical prostatectomy specimens with HGPIN adjacent to (n=54) or distant from adenocarcinoma (n=64). P504S expression was negative to weakly positive in biopsy specimens showing HGPIN without carcinoma and weakly positive in radical prostatectomy specimens revealing HGPIN distant from adenocarcinoma. In biopsy specimens with a combination of HGPIN and adenocarcinoma and in radical prostatectomy specimens with HGPIN adjacent to adenocarcinoma, P504S was strongly expressed. The same findings were made in radical prostatectomy specimens containing adenocarcinoma and HGPIN adjacent to or distant from adenocarcinoma and in preoperative biopsies revealing adenocarcinoma and HGPIN. These results suggest that moderate to strong P504S expression in HGPIN of biopsy specimens is indicative of an associated adenocarcinoma and may be helpful in the choice of therapy.     

Florid basal cell hyperplasia of the prostate: a histological,ultrastructural, and immunohistochemical analysis

Basal cell proliferation is a common finding in a benign hyperplastic prostate gland. Occasionally, basal cell hyperplasia is so florid that it can be mistaken for prostatic adenocarcinoma. We characterized histological, ultrastructural, and immunohistochemical features of florid basal cell hyperplasia from transurethral resections (n = 11) and prostatectomy specimens (n = 4). Fifteen cases of prostatic adenocarcinoma were used as comparison. Intraluminal calcification was present in 40% of florid basal cell hyperplasia cases (6 of 15) and a unique finding of intracytoplasmic hyaline globules was detected in 53.3% of florid basal cell hyperplasia cases (8 of 15). Ultrastructural analysis revealed luminal calcification and intracytoplasmic electron-dense globules in foci of basal cell hyperplasia. Crystalloids, a frequent finding in low-grade prostate cancer, were absent in all 15 cases of florid basal cell hyperplasia. By immunohistochemistry, the basal cell-specific 34betaE12 and p63 as well as glutathione-s-transferase pi were positive in all basal cell hyperplasia cases but negative in all prostatic adenocarcinomas. These distinguishing features of florid basal cell hyperplasia are helpful in differential diagnosis from prostatic adenocarcinoma. Cytokeratins 8 and 18 were both positive in basal cells, benign secretory cells, and carcinoma cells, failing to be of discrimatory value. Immunostaining for alpha-methylacyl-coenzyme racemase, a new prostate cancer marker, was negative in hyperplastic basal cells but detected a distinct minor benign cell population in basal cell hyperplasia of possible neuroendocrine origin.     

α‐Methylacyl‐CoA racemase (AMACR) in fine‐needle aspiration specimens of prostate lesions

The elevated expression of P504S gene and its product α‐methylacyl‐CoA racemase (AMACR) can serve as a molecular marker for prostate cancer. The goal of this study is to investigate P504S/AMACR expression in fine‐needle aspiration smears and correlate it with cytological diagnosis. Immunocytochemistry was performed in 35 patients with morphological diagnosis of prostate carcinoma (n = 16), atypia (n = 15), and benign hyperplasia (n = 4). Among 16 malignant cases there were two low‐grade, eight intermediate, and six high‐grade prostate carcinomas. Cytoplasmic positivity is analyzed qualitatively as predominantly diffuse or focal and quantitatively as <5%, 5–50%, and >50% of cells. Benign cases showed no P504S/AMACR expression. Positive staining was recorded in 75% of malignant cases, but in the majority of them it was weak and focal or diffuse and in a small amount of cells. The most intensive staining was seen in low‐grade carcinomas and some atypical cases. This observation indicates a correlation between P504S/AMACR expression and differentiation of cells. P504S/AMACR staining might be of great value in cytodiagnosis of prostate lesions as well as an example of the characterization of cells at the molecular level using fresh tissue obtained by fine‐needle aspiration. Diagn. Cytopathol. 2009. © 2009 Wiley‐Liss, Inc.     

前列腺摘除病检和穿刺活检的形态学差异

目的：探讨前列腺摘除病检和穿刺活检的形态学差异。方法：对340例穿刺标本和280例因良性前列腺增生（BPH）而摘除的前列腺标本进行形态学对比分析。结果：在穿刺活检中,前列腺癌,上皮内新生物（PIN）和非特异性肉芽肿性前列腺炎（NSGP）的检出率明显高于摘除者,在前列腺摘除的标本中,梗死,磷化,间质增生性结节,腺性尿道炎和非典型性腺瘤样增生（AAH）的检出率明显市政地穿刺活检,结论：形态学差异是由于穿刺和摘除标本分别取自前列腺不同解剖并且并且部位所致,对穿刺和摘除前列腺的病理诊断,应该有不同的鉴别诊断思路。     

Fine needle aspiration biopsy of the prostate gland

With the worldwide acceptance of mechanically assisted, ultrasound guided thin needle biopsy of the prostate gland, prostate fine needle aspiration (FNA) has fallen out of favor with both urologists and cytopathologists. Nonetheless, given today's trend to submit from 12 to 18 core biopsies per patient, prostate FNA remains less expensive, more expedient and more economical than any other sampling method so far developed. This short overview presents prostate FNA as a sensitive, specific and reliable diagnostic modality that should not be dismissed, as an anachronism, from the diagnostic armamentarium of either the urologist or the pathologist.     

Discrepancies between Gleason scores of needle biopsy and radical prostatectomy specimens

The purpose of this study was to determine the accuracy of Gleason scores in prostate needle biopsy diagnosis and to investigate factors affecting the accuracy of the tumor grade. A single pathologist reviewed 116 sets of prostate cancer biopsies and radical prostatectomy specimens. The following factors were examined to determine their effect on the accuracy of the biopsy Gleason scores: (i) relative tumor differentiation; (ii) pathological stage; (iii) amount of tissue in the biopsy specimen; (iv) amount of cancer tissue in the biopsy specimen; (v) tumor heterogeneity; (vi) clinical findings (prostate specific antigen value and digital rectal examination); and (vii) interobserver variability. In 53 cases the Gleason score of biopsy specimens was identical to the score of prostatectomy specimens (45.7%). Fifty-four cases (46.6%) of biopsy specimens were undergraded. The most common discrepancy was diagnosis of well-differentiated carcinoma in the biopsy but diagnosis of moderately differentiated tumor in the corresponding prostatectomy specimen. This discrepancy occurred when the amount of tumor in the biopsy was 3 mm or less. Biopsy and prostatectomy results showed less agreement when the original biopsy tumor grade rendered by nine different pathologists was used, suggesting that interobserver variability can adversely affect the accuracy of tumor grade. Clarifying the histologic criteria for distinguishing each grade, especially between Gleason grades 2 and 3, is important for accurate grading.     

Using an AMACR (P504S)/34betaE12/p63 cocktail for the detection of small focal prostate carcinoma in needle biopsy specimens

We assessed the usefulness of immunohistochemical analysis with a 3-antibody cocktail (alpha-methylacyl coenzyme A racemase [AMACR, or P504S], 34betaE12, p63) and a double-chromogen reaction for detection of limited prostate cancer in 138 needle biopsy specimens, including 82 with small foci of prostatic adenocarcinoma and 56 benign prostates. When carcinoma was present, red cytoplasmic granular staining (AMACR) in the malignant glands and cells and dark brown nuclear (p63) and cytoplasmic (34betaE12) staining in basal cells of adjacent nonmalignant glands were found. Of 82 cases of small foci of prostatic adenocarcinoma, 78 (95%) expressed AMACR; all malignant glands were negative for basal cell staining. All benign glands adjacent to malignant glands were recognized easily by basal cell marker positivity and little or no AMACR expression. No benign glands were simultaneously positive for AMACR and negative for basal cell markers (specificity, 100%). There were no differences in intensity and numbers of positive glands with double-chromogen staining compared with using 1-color staining. Our results indicate that immunohistochemistry with a 3-antibody cocktail and double chromogen is a simple and easy assay that can be used as a routine test, which overcomes the problems of studying small lesions in prostate needle biopsies with multiple immunohistochemical stains.     

Florid basal cell hyperplasia of the prostate

Florid basal cell hyperplasia of the prostate is an uncommon proliferative condition, most often associated with adenomatous hyperplasia. It is considered a benign lesion although confusion with prostatic cancer is possible when one is not familiar with the histopathological appearance. We report another two cases of the glandular type of basal cell hyperplasia with immunohistochemical findings. Both lesions were composed of crowded and rather small glands with piling up of basaloid cells. They showed immunohistochemical positivity for high molecular weight cytokeratin 34βE12, confirming their relationship with basal cells. We detected focal positivity of these basal cells for α-smooth muscle actin, suggesting myoepithelial differentiation. Paucity of actin-positive smooth muscle cells in the stroma was noticed. One of the lesions showed some mild cytological atypia with prominent nucleoli and increased mitotic activity.     

Diagnostic utility of alpha-methylacyl CoA racemase (P504S) on prostate needle biopsy

Alpha-methylacyl CoA racemase (AMACR), also known as P504S, was identified by the analysis of cDNA library subtraction in conjunction with high throughput microarray screening from prostate tissue and has been proven to be one of the very few biomarkers that can distinguish cancer from benign cells with high sensitivity and specificity for prostate carcinoma. It is a successful example of the translation of molecular findings into clinical practice. This review focuses on the study of AMACR (P504S) expression in small focal prostate cancer and atypical small acinar proliferation (ASAP) on needle biopsies and emphasizes the utility of AMACR (P504S) in routine surgical pathology practice. We also discuss the potential pitfalls and caveats in the interpretation of immunostaining results.     

Basal cell hyperplasia, adenoid basal cell tumor, and adenoid cystic carcinoma of the prostate gland: An immunohistochemical study

Basal cell hyperplasia (BCH) is an uncommon proliferative lesion of the prostate gland. We studied ten cases of BCH, one case of an unusual adenoid basal cell tumor (ABT), and one case of a prostatic adenoid cystic carcinoma (ACC), using a panel of antibodies to define the histogenesis of these lesions. Monoclonal antibodies (MoAb) directed against a cytokeratin, which selectively stains basal cells (34 beta E12), and against muscle-specific actin, which stains myoepithelial cells (HHF35), were used. In addition, antibodies directed against prostatic acid phosphatase (PAP), prostate-specific antigen (PSA), S-100 protein, and vimentin were used. In the normal prostate, epithelial cells reacted positively with 34 beta E12, PAP, and PSA, and negatively with the actin, S-100 protein, and vimentin antibodies. In BCH, positive staining was seen for 34 beta E12, PSA, and PAP, with no reactivity for actin, S-100 protein, and vimentin. In ABT and ACC, positive reactivity was demonstrated for all antibodies except actin and vimentin. These findings indicate that the basaloid cells of BCH, ABT, and ACC are derived from basal cells of the normal prostate gland and suggest a continuum among the three lesions. The presence of S-100 protein in ABT and ACC may be related to the lack of this antigen's specificity for myoepithelial cells. The absence of reactivity with the HHF35 MoAb supports our belief that the S-100 positivity does not necessarily indicate myoepithelial cell differentiation.     

Sensitivity of P504S/alpha-methylacyl-CoA racemase (AMACR) immunohistochemistry for the detection of prostate carcinoma on stored needle biopsies.

Alpha methylacyl-CoA-racemase (AMACR), also known as P504S, has been widely used as a positive marker for the diagnosis of prostate carcinoma in clinical practice. The utility of this assay is highly dependent on the sensitivity of AMACR detection in routinely processed biopsies. It is common practice to store precut prostate biopsy sections. Hence, it is important to determine the effect on the immunoreactive of P504S/AMACR in stored, unstained glass slides as compared with freshly cut sections of paraffin-embedded tissue. The purpose of this study was to determine the sensitivity of AMACR immunostaining for the detection of prostate carcinoma on stored needle biopsies. A total of 63 prostate biopsies with prostate carcinoma were transferred onto glass slides, baked, and stored for 1.6 to 9.2 months. The Gleason scores were 3+3(6) (n=40) including 10 small focal carcinomas (< or = 1.0 mm), 4+3(7) (n=16), and 4+4(8) or higher (n=7). The slides were then stained with a monoclonal antibody to P504S, and the staining intensity was compared with sections cut from the same blocks just prior to immunostaining, without an intervening storage period. There was no loss of sensitivity of AMACR for prostate adenocarcinoma, regardless of the length of the storage interval. The sensitivity was preserved and was independent of Gleason scores. The sensitivity of AMACR for small foci of adenocarcinoma was also not affected by the length of storage. Overall, stored slides had no observable increase in nonspecific background staining over freshly cut sections. These results indicate that the time interval between mounting and staining does not affect the sensitivity of the AMACR immunohistochemistry (IHC) stain in the detection of prostate cancer even with small foci of carcinoma on needle biopsies.     

The usefulness of S100P,mesothelin, fascin,prostate stem cell antigen,and 14‐3‐3 sigma in diagnosing pancreatic adenocarcinoma in cytological specimens obtained by endoscopic ultrasound guided fine‐needle aspiration

Endoscopic ultrasound‐guided fine‐needle aspiration (EUS‐FNA) of the pancreas is an efficient and minimally invasive procedure for the diagnosis and staging of pancreatic adenocarcinoma. Because of some limitations of EUS‐FNA in diagnosis of well‐differentiated or early stage cancers, the purpose of this study is to assess the added benefit of immunohistochemistry. We studied five proteins overexpressed in pancreatic adenocarcinoma, namely, prostate stem cell antigen, fascin, 14‐3‐3 sigma, mesothelin and S100P utilizing immunohistochemistry on paraffin sections from cellblocks obtained by EUS‐FNA. Sixty‐two cases of EUS‐FNA of the pancreas that had follow‐up histological and/or clinical diagnosis and sufficient material in cell blocks were included. Using histological diagnosis and/or clinical outcome as the reference standard, EUS‐FNA shows the highest sensitivity (95%) and specificity (91%) and is superior to any marker in this study. Among five antibodies, S100P reveals the best diagnostic characters showing 90% of sensitivity and 67% of specificity. Fascin shows high specificity (92%) but low sensitivity (38%). Mesothelin has a moderate sensitivity (74%) and low specificity (33%), PSCA and 14‐3‐3 show high sensitivity but zero specificity. S100P and mesothelin were useful in nine indeterminate cases. S100P correctly predicted six of seven cancers and one of one without cancer and mesothelin correctly diagnosed five of seven cancers and one of two noncancers in this group. EUS‐FNA cytomorphology is superior to any of the immunohistochemical markers used in this study. Use of S100P and mesothelin in cytologically borderline cases can increase the diagnostic accuracy in this group. Diagn. Cytopathol. 2014;42:193–199. © 2011 Wiley Periodicals, Inc.     

Expression of alpha-methylacyl-CoA racemase (P504s) in various malignant neoplasms and normal tissues: astudy of 761 cases

Alpha-methylacyl CoA racemase (AMACR), also known as P504S, plays an important role in peroxisomal beta-oxidation of branched-chain fatty acids. It has recently been shown that AMACR is highly expressed in prostate cancer and that it may be an important diagnostic marker for prostate carcinoma. However, little is known about expression of AMACR in normal tissues and other malignant tumors. In this study, we investigated expression of AMACR in 539 malignant tumors and 222 normal human tissues of various types by immunohistochemical analysis. mRNA levels of AMACR in normal organs and in selected tumors were assessed by real time PCR. In normal tissue, high expression of AMACR mRNA was identified in liver, kidney and salivary gland, while AMACR protein was detected in liver (hepatocytes), kidney (tubular epithelial cells), lung (only bronchial epithelial cells), and gallbladder (only mucosal epithelial cells). High expression of AMACR mRNA was found in prostate, liver, and kidney cancers but rarely in stomach and bladder cancers. A high percent of adenocarcinomas arising from these organs express AMACR, including 17 of 21 (81%) of hepatocellular carcinomas and 18 of 24 (75%) of renal cell carcinomas. In addition, carcinomas arising from tissues normally not expressing AMACR were also positive for the antigen, including 17 of 18 (94%) prostate carcinomas, 9 of 29 (31%) of urothelial carcinomas, and 4 of 15 (27%) of gastric adenocarcinomas. Two hundred and fifty cases of adenocarcinomas from lung, breast, pancreas, bile duct, adrenal gland, salivary gland, ovary, thyroid and endometrium were negative or rarely positive for AMACR. Neuroendocrine carcinomas rarely expressed AMACR. Melanomas, squamous cell carcinomas, basal cell carcinomas, soft tissue tumors (including epithelioid sarcomas and synovial sarcoma), thymomas, and germ cell tumors were negative for AMACR. Our data provide important baseline information for using AMACR in clinical practice and also are valuable in furthering understanding of the pathogenic role of AMACR in malignant neoplasms.     

Negative 34betaE12 staining in a small focus of atypical glands on prostate needle biopsy: a follow-up study of 332 cases

Atypical glands on prostate needle biopsy with a negative 34betaE12 (cytokeratin 903; CK903) immunostain, indicating a lack of a basal cell layer, are typically diagnostic of prostate cancer. However, in certain cases a negative 34betaE12 immunostain in a small focus of atypical glands is still not convincing enough to make the diagnosis of cancer. This study is the first report to evaluate the incidence of prostate cancer on follow-up biopsy in individuals with this diagnosis. A total of 543 men who had prostate core biopsy specimens diagnosed as a small focus of atypical-appearing glands with a negative 34betaE12 immunostain between January 1, 1997 and December 31, 2000 were selected for study. Some 61% of these 543 individuals (n = 332) had undergone at least one follow-up biopsy procedure. Of these, 43% of repeat biopsy cases (n = 142) were diagnostic of prostate cancer. A total of 46 individuals had at least 2 follow-up biopsy procedures, with 48% of these (n = 22) being diagnosed as cancer. The Gleason grades of the detected carcinomas were broken down as follows: Gleason grade 3 + 2 = 5, 6%; grade 3 + 3 = 6, 86%; grade 3 + 4 = 7, 1%; grade 4 + 3 = 7, 4%; and grade 4 + 4 = 8, 3%. The median amount of time to the first follow-up biopsy was 79 days, with 52% of follow-up biopsies performed within 90 days. A negative 34betaE12 immunohistochemical stain in a small focus of atypical glands is not associated with an increased prediction of prostate cancer on follow-up biopsy (43%), compared with previously published data for "small focus of atypical glands" alone (approximately 45%). Because 48% of men with an initial negative biopsy and multiple follow-up biopsy procedures were found to have cancer, more than one repeat biopsy session or more extensive sampling on the first repeat biopsy procedure may be necessary to maximize the identification of cancer. This finding is similar to that found in men with atypical diagnoses in general, without a negative 34betaE12 immunohistochemical stain. Only half of all individuals with a diagnosis of 34betaE12-negative focus of atypical glands underwent repeat biopsy within 3 months. Urologists need to be educated as to the significance of an atypical diagnosis and the need for repeat biopsy. In a small focus of atypical glands on prostate biopsy, negative staining for 34betaE12 should not necessarily lead to a definitive malignant diagnosis in all cases, because almost half of these biopsies on follow-up sampling are benign.