The distribution of PAX-2 immunoreactivity in the prostate gland, seminal vesicle, and ejaculatory duct: comparison with prostatic adenocarcinoma and discussion of prostatic zonal embryogenesis

Apparent differences in prostate zones: susceptibility to prostate cancer, benign prostatic hyperplasia and prostatitis

Men are inevitably plagued by prostate disease throughout their lives. However, the understanding of the pathogenesis of prostate diseases is still limited. In the 1960s, McNeal proposed the theory of prostate zones: the prostate was divided into three main zones: transition zone, central zone, and peripheral zone. Over the past 50 years, significant differences between different prostate zones have been gradually revealed. We summarized the most significant differences in different zones of the prostate. For the first time, we proposed the "apparent difference in prostate zones" concept. This new concept has been proposed to understand the different zones of the prostate better. It also provided new ideas for exploring the susceptibility of lesions in different prostate zones. Despite the reported differences between zones, the treatment of prostate-related diseases remains partition agnostic. Therefore, we also discussed the clinical significance of the "apparent difference in the prostate zone" and emphasized the necessity of prostate zones.

Prostate zones and cancer: lost in transition?

Localized prostate cancer shows great clinical, genetic and environmental heterogeneity; however, prostate cancer treatment is currently guided solely by clinical staging, serum PSA levels and histology. Increasingly, the roles of differential genomics, multifocality and spatial distribution in tumorigenesis are being considered to further personalize treatment. The human prostate is divided into three zones based on its histological features: the peripheral zone (PZ), the transition zone (TZ) and the central zone (CZ). Each zone has variable prostate cancer incidence, prognosis and outcomes, with TZ prostate tumours having better clinical outcomes than PZ and CZ tumours. Molecular and cell biological studies can improve understanding of the unique molecular, genomic and zonal cell type features that underlie the differences in tumour progression and aggression between the zones. The unique biology of each zonal tumour type could help to guide individualized treatment and patient risk stratification.

Müllerian duct cyst: Case report with updates in cellular origin, corresponding immunohistochemistry, and contrast to prostatic utricle cyst

A 20-year-old male presented to the emergency department with lower abdominal pain, urinary retention, and constipation. Computed tomography (CT) revealed a large cyst on the posterior aspect of the prostate gland; he was ultimately diagnosed with a Müllerian duct cyst (MDC). Although much has been written on the radiologic diagnosis of such cysts, there is a paucity of recent literature concerning the pathological diagnosis. While older studies debated the Müllerian origin of a midline cyst abutting the poster prostate, we believe that with the advent of monoclonal PAX8 (which was positive in this lesion) and monoclonal PAX2 (which was negative), we have strong evidence that the present cyst is indeed of Müllerian origin. Further, there is debate in the literature as to whether MDC is synonymous or distinct from prostatic utricle cyst. We present an interdisciplinary analysis as to the merits and weaknesses of both sides of the debate and how data gathered from the current case could be used in a future, larger study to arrive at a more definitive conclusion.

Utility of NKX3.1 immunohistochemistry in the differential diagnosis of seminal vesicles versus prostatic tissue in needle biopsy

NKX3.1 is considered a reliable immunohistochemical marker of prostatic origin with high specificity and sensitivity. However, NKX3.1 positivity has been described in other neoplastic and non-neoplastic tissues, such as mesenchymal chondrosarcoma, sex-cord stromal tumors, rete testis adenocarcinoma, lobular and ductal carcinoma of the breast, salivary glands, peribronchial submucosal glands, and Sertoli cells. We analyzed expression of two antibodies (mono and polyclonal) of NKX3.1 in a total of 63 non-neoplastic seminal vesicles. We used 52 resection materials (12 seminal vesicles without prostatic adenocarcinoma, 26 seminal vesicles with prostatic adenocarcinoma infiltration, and 14 cases of seminal vesicles infiltrated by urothelial carcinoma) and 11 prostatic core needle biopsies with incidentally sampled fragment of seminal vesicles. In all cases, tissues from seminal vesicles were completely negative for NKX3.1, despite using polyclonal and monoclonal NKX3.1 antibodies, and regardless of the detection system utilized (diaminobenzidine (DAB) versus alkaline phosphatase (AF)). However, prostatic adenocarcinoma was negative in several cases (n = 6), when AF detection system was used. Reaction with DAB was strong and robust in all cases. Based on our data, we can recommend NKX3.1 as a negative immunohistochemical marker of seminal vesicles.

PI-RADS version 2.1: one small step for prostate MRI

Multiparametric (mp) prostate magnetic resonance imaging (MRI) is playing an increasingly prominent role in the diagnostic work-up of patients with suspected prostate cancer. Performing mpMRI before biopsy offers several advantages including biopsy avoidance under certain clinical circumstances and targeting biopsy of suspicious lesions to enable the correct diagnosis. The success of the technique is heavily dependent on high-quality image acquisition, interpretation, and report communication, all areas addressed by previous versions of the Prostate Imaging-Reporting and Data System (PI-RADS) recommendations. Numerous studies have validated the approach, but the widespread adoption of PI-RADS version 2 has also highlighted inconsistencies and limitations, particularly relating to interobserver variability for evaluation of the transition zone. These limitations are addressed in the recently released version 2.1. In this article, we highlight the key changes proposed in PI-RADS v2.1 and explore the background reasoning and evidence for the recommendations.

Epithelial DNA methyltransferase-1 regulates cell survival, growth and maturation in developing prostatic buds

DNA methyltransferase 1 (DNMT1) is required for embryogenesis but roles in late forming organ systems including the prostate, which emerges from the urethral epithelium, have not been fully examined. We used a targeted genetic approach involving a Shhcre recombinase to demonstrate requirement of epithelial DNA methyltransferase-1 (Dnmt1) in mouse prostate morphogenesis. Dnmt1 mutant urethral cells exhibit DNA hypomethylation, DNA damage, p53 accumulation and undergo cell cycle arrest and apoptosis. Urethral epithelial cells are disorganized in Dnmt1 mutants, leading to impaired prostate growth and maturation and failed glandular development. We evaluated oriented cell division as a mechanism of bud elongation and widening by demonstrating that mitotic spindle axes typically form parallel or perpendicular to prostatic bud elongation axes. We then deployed a Shh^creERT allele to delete Dnmt1 from a subset of urethral epithelial cells, creating mosaic mutants with which to interrogate the requirement for cell division in specific prostatic bud epithelial populations. DNMT1- cell distribution within prostatic buds is not random as would be expected in a process where DNMT1 was not required. Instead, replication competent DNMT1 + cells primarily accumulate in prostatic bud margins and tips while replication impeded DNMT1- cells accumulate in prostatic bud cores. Together, these results highlight the role of DNMT1 in regulating epithelial bud formation by maintaining cell cycle progression and survival of rapidly dividing urethral epithelial cells, which can be extended to the study of other developing epithelial organs. In addition, our results show that prostatic buds consist of two epithelial cell populations with distinct molecular and functional characteristics that could potentially contribute to specialized lineages in the adult prostate.

Benign mimics of prostatic adenocarcinoma

Benign mimics present either as common challenges in daily routine practice or may cause diagnostic dilemmas because some are less commonly seen and one may be less familiar in recognizing them. There are a multitude of mimics of prostatic adenocarcinoma, which may represent normal gland structures, benign proliferations, atrophic lesions, hyperplastic or metaplastic changes, and inflammatory processes. Some of them are preferentially found in certain anatomic areas of the prostate, either confined to the prostate, or outside of the gland. Various benign mimics of prostatic carcinoma may be also evaluated based on their morphologic similarity to Gleason patterns 3-5 of prostatic adenocarcinoma. Most of the mimics are easily recognizable in larger specimens, such as TUR of the prostate or radical prostatectomy specimens, but they may pose diagnostic problems when the evaluation is done on limited tissue, such as needle-core biopsies or if prostate specimens are infrequently encountered in practice. Therefore, before signing out a report with a diagnosis of prostatic carcinoma, pathologists should carefully consider and rule out the various benign lesions that may mimic carcinoma. This is particularly relevant in the current prostate biopsy practice which relies on using extended biopsy core templates. The awareness and familiarity with the characteristic features of the mimics and judicial use of additional ancillary tests, including immunohistochemistry can prevent overdiagnosis and false-positive interpretation. This review provides a contemporary update on the broad spectrum of the benign prostatic lesions that can mimic prostate adenocarcinoma, outlines their key morphologic and immunohistochemical diagnostic features, and provides a diagnostic, pattern-based approach in establishing a correct diagnosis and distinguishing them reliably from prostatic adenocarcinoma.

Vasitis nodosa and related lesions: a modern immunohistochemical staining profile with special emphasis on novel diagnostic dilemmas

Vasitis nodosa is a benign proliferation of vas deferens epithelium, thought to be a response to trauma or obstruction, usually vasectomy. Although histologic features mimic malignancy, diagnosis is usually straightforward due to the clinical context. We analyzed 21 specimens with vasitis or epididymitis nodosa with antibodies to PAX8, CD10, p63, α-methyl-acyl-coA-racemase (AMACR), GATA3, prostein, NKX3.1, and prostate-specific antigen (PSA). Two diagnostically problematic cases included (1) florid bladder muscle involvement after prostatectomy and (2) involvement of the ampulla and ejaculatory duct in a radical prostatectomy specimen. Vasitis nodosa was excluded in 3 additional histologic mimics (2 post-treatment prostate cancers and 1 bladder cancer). PAX8 yielded consistent positive (100%) nuclear staining in the proliferative glands of vasitis nodosa, often stronger and more uniform than native vas deferens. CD10 labeling was common but also labeled secretions and other structures. Labeling for p63 was often basally located in glands with a multilayered appearance, but often markedly attenuated or lacking in the proliferative glands compared to native epithelium. AMACR positivity was variable but often present (19/21). PSA, prostein, and NKX3.1 were consistently negative. Rare problematic cases of vasitis nodosa include "invasion" of the ejaculatory duct at the prostate and involvement of bladder muscle after prostatectomy. The proliferative vasitis nodosa glands often have a prostate cancer-like staining pattern with variable AMACR positivity and negative or patchy p63. However, reliable positivity for PAX8, patchy GATA3, and negative staining for PSA, NKX3.1, and prostein aid in distinguishing from prostate cancer and tubular variants of bladder cancer.

Diagnosis of typical and atypical transition zone prostate cancer and its mimics at multiparametric prostate MRI

Many of the current clinical screening methods for prostate cancer (PCa) such as prostate-specific antigen (PSA) testing or transrectal ultrasound-guided prostate biopsy lack sensitivity and specificity for diagnosis of PCa of the transition zone (TZ). Recent technical advances in multiparametric-MRI have markedly improved detection of PCa of the TZ. However, there are many diagnostic challenges that we still encounter in our daily practice that compromise the accuracy of the diagnosis. By performing both MRI-guided and ultrasound/MRI fusion-guided biopsies, we have gained extensive experience in the diagnosis of PCa of the TZ. Biopsy-proven examples including but not limited to typical and atypical PCa of the TZ as well as a wide variety of its mimics will be presented. Recognition of the MR features of typical and atypical PCa of the TZ and its mimics on multiparametric-MRI along with findings that help to differentiate these mimics from PCa is important in establishing an accurate diagnosis and in guiding clinical management.

Seminal epithelium in prostate biopsy can mimic malignant and premalignant prostatic lesions

OBJECTIVES

In most prostate biopsies, the seminal epithelium is easily recognised because it meets characteristic histological criteria. However, some biopsies can mimic malignant or premalignant prostatic lesions. The aims of this study were to analyse the histological appearance of the biopsies that mimic adenocarcinomas or preneoplastic prostatic lesions, discuss the differential diagnosis and determine the frequency of seminal epithelia in prostate biopsies.

METHODS

We consecutively reviewed 500 prostate puncture biopsies obtained using the sextant method and selected those cases in which we observed seminal vesicle or ejaculatory duct epithelium. In the biopsies in which the seminal epithelium resembled malignant or premalignant lesions, immunohistochemical studies were conducted that included prostate-specific antigen and MUC6. The most important clinical data were recorded.

RESULTS

Thirty-six (7.2%) biopsies showed seminal epithelium, and 7 of them (1.4%) resembled various prostate lesions, including high-grade prostatic intraepithelial neoplasia, atypical acinar proliferations, adenocarcinomas with papillary patterns and poorly differentiated carcinoma. The seminal epithelium resembled prostate lesions when the lipofuscin deposit, the perinuclear vacuoles or the nuclear pseudoinclusions were inconspicuous or missing. Five of the 7 biopsies showed mild to moderate cellular atypia with small and hyperchromatic nuclei, and only 2 showed cellular pleomorphism. The patients were alive and asymptomatic after an average of 6 years of progression.

CONCLUSIONS

The seminal epithelium resembles prostatic intraepithelial neoplasia, atypical acinar proliferations and various types of prostatic adenocarcinomas in approximately 1.4% of prostate biopsies.

GATA3 Is a Sensitive and Specific Marker of Benign and Malignant Mesonephric Lesions in the Lower Female Genital Tract

GATA3 is a transcription factor critical for embryogenesis, development, and cell differentiation. Recent studies have suggested that GATA3 is a sensitive and relatively specific biomarker for urothelial and breast carcinomas, with most Müllerian carcinomas being negative. We investigated GATA3 expression in mesonephric/Wolffian remnants and tumors in the female genital tract. A western blot was performed to assess specificity for the GATA3 antibody. GATA3 immunohistochemistry was performed on 59 formalin-fixed paraffin-embedded mesonephric samples, including 17 mesonephric remnants (MR; 11 cervical and 6 fallopian tube), 15 mesonephric hyperplasias, 21 mesonephric carcinomas, and 6 female adnexal tumors of probable Wolffian origin. Thirty conventional endocervical adenocarcinomas (ENDO-CA), 9 gastric-type cervical adenocarcinomas, and 165 endometrial adenocarcinomas (EM-CA) were also evaluated. GATA3 nuclear intensity and extent of staining was evaluated. The western blot revealed GATA3 expression in seminal vesicle and cell lines derived from breast and urothelial carcinomas, but not in other cell lines including ovarian, cervical, and endometrial cancers. All cervical MRs and mesonephric hyperplasias, 5/6 (83%) fallopian tube MRs, and 20/21 (95%) mesonephric carcinomas were GATA3 positive, although with great variability in both intensity (weak to strong) and extent (1+ to 3+) of staining. Only 1/6 (17%) female adnexal tumors of probable Wolffian origin showed weak multifocal staining. One of 30 (3%) usual-type ENDO-CAs and 3/165 EM-CAs exhibited weak-moderate GATA3 immunoreactivity; all gastric-type cervical adenocarcinomas were negative. GATA3 is a highly sensitive and specific marker for mesonephric lesions in the lower genital tract; however, its utility in the upper genital tract may be more limited. In addition, GATA3 can aid in distinguishing lower genital mesonephric lesions from usual-type and gastric-type ENDO-CAs and uterine EM-CAs.

Apparent Diffusion Coefficient Values of the Benign Central Zone of the Prostate: Comparison With Low- and High-Grade Prostate Cancer

OBJECTIVE

The apparent diffusion coefficient (ADC) values for benign central zone (CZ) of the prostate were compared with ADC values of benign peripheral zone (PZ), benign transition zone (TZ), and prostate cancer, using histopathologic findings from radical prostatectomy as the reference standard.

MATERIALS AND METHODS

The study included 27 patients with prostate cancer (mean [± SD] age, 60.0 ± 7.6 years) who had 3-T endorectal coil MRI of the prostate performed before undergoing prostatectomy with whole-mount histopathologic assessment. Mean ADC values were recorded from the ROI within the index tumor and within benign CZ, PZ, and TZ, with the use of histopathologic findings as the reference standard. ADC values of the groups were compared using paired t tests and ROC curve analysis.

RESULTS

The ADC of benign CZ in the right (1138 ± 123 × 10(-6) mm(2)/s) and left (1166 ± 141 × 10(-6) mm(2)/s) lobes was not significantly different (p = 0.217). However, the ADC of benign CZ (1154 ± 129 × 10(-6) mm(2)/s) was significantly lower (p < 0.001) than the ADCs of benign PZ (1579 ± 197 × 10(-6) mm(2)/s) and benign TZ (1429 ± 180 × 10(-6) mm(2)/s). Although the ADC of index tumors (1042 ± 134 × 10(-6) mm(2)/s) was significantly lower (p = 0.002) than the ADC of benign CZ there was no significant difference (p = 0.225) between benign CZ and tumors with a Gleason score of 6 (1119 ± 87 × 10(-6) mm(2)/s). In 22.2% of patients (6/27), including five patients who had tumors with a Gleason score greater than 6, the ADC was lower in benign CZ than in the index tumor. The AUC of ADC for the differentiation of benign CZ from index tumors was 72.4% (sensitivity, 70.4%; specificity, 51.9%), and the AUC of ADC for differentiation from tumors with a Gleason score greater than 6 was 76.7% (sensitivity, 75.0%; specificity, 65.0%).

CONCLUSION

The ADC of benign CZ is lower than the ADC of other zones of the prostate and overlaps with the ADC of prostate cancer tissue, including high-grade tumors. Awareness of this potential diagnostic pitfall is important to avoid misinterpreting the normal CZ as suspicious for tumor.

Dynamic contrast-enhanced MR imaging features of the normal central zone of the prostate

RATIONALE AND OBJECTIVES

Evaluate qualitative dynamic contrast-enhanced magnetic resonance imaging (MRI) characteristics of normal central zone based on recently described central zone MRI features.

MATERIALS AND METHODS

Institutional review board-approved, Health Insurance Portability and Accountability Act compliant study, 59 patients with prostate cancer, histopathology proven to not involve central zone or prostate base, underwent endorectal MRI before prostatectomy. Two readers independently reviewed T2-weighted images and apparent diffusion coefficient (ADC) maps identifying normal central zone based on low signal intensity and location. Next, two readers drew bilateral central zone regions of interest on dynamic contrast-enhanced magnetic resonance images in consensus and independently recorded enhancement curve types as type 1 (progressive), type 2 (plateau), and type 3 (wash-out). Identification rates of normal central zone and enhancement curve type were recorded and compared for each reviewer. The institutional review board waiver was approved and granted 05/2010.

RESULTS

Central zone identified in 92%-93% of patients on T2-weighted images and 78%-88% on ADC maps without significant difference between identification rates (P = .63 and P = .15 and inter-reader agreement (κ) is 0.64 and 0.29, for T2-weighted images and ADC maps, respectively). All central zones were rated either curve type 1 or curve type 2 by both radiologists. No statistically significant difference between the two radiologists (P = .19) and inter-reader agreement was κ = 0.37.

CONCLUSIONS

Normal central zone demonstrates either type 1 (progressive) or type 2 (plateau) enhancement curves on dynamic contrast-enhanced MRI that can be potentially useful to differentiate central zone from prostate cancer that classically demonstrates a type 3 (wash-out) enhancement curve.

[Benign mimickers of the prostate cancer. Diagnostic challenges]

The diagnosis of prostate cancer (PCa), especially limited adenocarcinoma on needle biopsy, is often challenging. Before making diagnosis of PCa, it is prudent for the pathologist to consider different benign patterns that may lead to a false positive interpretation. Histoanatomic structures such as seminal vesicles, Cowper's glands and paraganglia along with hyperplasia, atrophy with its different patterns and adenosis may generate difficulties in differential diagnosis. Furthermore, inflammatory processes and post-treatment changes may cause problems. The above entities can in some instances simulate low-grade and less commonly high grade PCa. Knowledge of these patterns and application of appropriate immunohistochemistry will lead the pathologist to a correct diagnosis.

Value of PAX2 immunostaining in tumor diagnosis: a review and update

PAX2 is a member of the PAX family of transcription factors that, together with PAX8, is involved in the regulation of the organogenesis of the kidney and the Müllerian system. Recent investigations have demonstrated that, among tumors, PAX2 is commonly expressed in epithelial tumors of the kidney and female genital tract. Although PAX2 expression has also been reported in B-cell lymphomas and rhabdomyosarcomas, especially alveolar rhabdomyosarcomas, it has been suggested that the positivity in these tumors was most probably due to a cross-reactivity of the anti-PAX2 antibody used in those investigations with other members of the PAX protein family. An analysis of published studies indicates that PAX2 sensitivity for epithelial renal neoplasms and epithelial tumors of the female genital tract is lower than that of PAX8. In contrast to the latter marker, however, PAX2 does not appear to be expressed in epithelial tumors of the thyroid gland or thymus. Because of its restricted expression, PAX2 has proved to be a useful immunohistochemical marker with a wide range of diagnostic applications in surgical pathology, some of which will be briefly reviewed.

Normal central zone of the prostate and central zone involvement by prostate cancer: clinical and MR imaging implications

PURPOSE

To describe the anatomic features of the central zone of the prostate on T2-weighted and diffusion-weighted (DW) magnetic resonance (MR) images and evaluate the diagnostic performance of MR imaging in detection of central zone involvement by prostate cancer.

MATERIALS AND METHODS

The institutional review board waived informed consent and approved this retrospective, HIPAA-compliant study of 211 patients who underwent T2-weighted and DW MR imaging of the prostate before radical prostatectomy. Whole-mount step-section pathologic findings were the reference standard. Two radiologists independently recorded the visibility, MR signal intensity, size, and symmetry of the central zone and scored the likelihood of central zone involvement by cancer on T2-weighted MR images and on T2-weighted MR images plus apparent diffusion coefficient (ADC) maps generated from the DW MR images. Descriptive summary statistics were calculated for central zone imaging features. Sensitivity, specificity, and area under the curve were used to evaluate reader performance in detecting central zone involvement.

RESULTS

For readers 1 and 2, the central zone was visible, at least partially, in 177 (84%) and 170 (81%) of 211 patients, respectively. The most common imaging appearance of the central zone was symmetric, homogeneous low signal intensity. Cancers involving the central zone had higher prostate-specific antigen values, Gleason scores, and rates of extracapsular extension and seminal vesicle invasion compared with cancers not involving the central zone (P < .05). Area under the curve, sensitivity, and specificity in detecting central zone involvement were 0.70, 0.30, and 0.96 for reader 1 and 0.65, 0.35, and 0.93 for reader 2, and these values did not differ significantly between T2-weighted imaging and T2-weighted imaging plus ADC maps.

CONCLUSION

The central zone was visualized in most patients. Cancers involving the central zone were associated with more aggressive disease than those without central zone involvement.

The use of immunohistochemistry in the diagnosis of metastatic clear cell renal cell carcinoma: a review of PAX-8, PAX-2, hKIM-1, RCCma, and CD10

The diagnosis of metastatic clear cell renal cell carcinoma may be difficult in some cases, particularly in the small image-guided biopsies that are becoming more common. As targeted therapies for renal cell carcinoma are now standard treatment, the recognition and diagnosis of renal cell carcinoma has become even more critical. Many adjunctive immunohistochemical markers of renal epithelial lineage such as CD10 and RCCma have been proposed as aids in the diagnosis of metastatic renal cell carcinoma, but low specificities often limit their utility. More recently described markers (PAX-2, PAX-8, human kidney injury molecule-1, hepatocyte nuclear factor-1-β, and carbonic anhydrase-IX) offer the potential for greater sensitivity and specificity in this diagnostic setting; however, knowledge of their expected staining in other neoplasms and tissues is critical for appropriate use. In this review, we discuss the most widely used immunohistochemical markers of renal lineage with an emphasis on their sensitivity and specificity for metastatic clear cell renal cell carcinoma. Subsequently, we present a variety of organ-specific differential diagnostic scenarios in which metastatic clear cell renal cell carcinoma might be considered and we propose immunopanels for use in each situation.