Atypical Intraductal Cribriform Proliferations of the Prostate Exhibit Similar Molecular and Clinicopathologic Characteristics as Intraductal Carcinoma of the Prostate

Histopathological evaluation and grading for prostate cancer: current issues and crucial aspects

ABSTRACT

A crucial aspect of prostate cancer grading, especially in low- and intermediate-risk cancer, is the accurate identification of Gleason pattern 4 glands, which includes ill-formed or fused glands. However, there is notable inconsistency among pathologists in recognizing these glands, especially when mixed with pattern 3 glands. This inconsistency has significant implications for patient management and treatment decisions. Conversely, the recognition of glomeruloid and cribriform architecture has shown higher reproducibility. Cribriform architecture, in particular, has been linked to the worst prognosis among pattern 4 subtypes. Intraductal carcinoma of the prostate (IDC-P) is also associated with high-grade cancer and poor prognosis. Accurate identification, classification, and tumor size evaluation by pathologists are vital for determining patient treatment. This review emphasizes the importance of prostate cancer grading, highlighting challenges like distinguishing between pattern 3 and pattern 4 and the prognostic implications of cribriform architecture and intraductal proliferations. It also addresses the inherent grading limitations due to interobserver variability and explores the potential of computational pathology to enhance pathologist accuracy and consistency.

Assessing the predictive value of intraductal carcinoma of the prostate (IDC-P) in determining abiraterone efficacy for metastatic hormone-sensitive prostate cancer (mHSPC) patients

BACKGROUND

This study explored the value of intraductal carcinoma of the prostate (IDC-P) in predicting the efficacy of abiraterone treatment in metastatic hormone-sensitive prostate cancer (mHSPC) patients.

METHODS

A retrospective study of 925 patients who underwent prostate biopsies to detect IDC-P was conducted, with participants divided into two cohorts. The first cohort of 165 mHSPC patients receiving abiraterone treatment was analyzed to compare therapeutic effectiveness between IDC-P positive and negative cases. Utilizing propensity score matching (PSM) to reduce bias, outcomes such as PSA response, progression-free survival (PSA-PFS), radiographic progression-free survival (rPFS), and overall survival were assessed. Additionally, the second cohort of 760 mHSPC patients compared the efficacy of abiraterone with conventional hormone therapy, focusing on differences between IDC-P positive and negative individuals.

RESULTS

After PSM, our first cohort included 108 patients with similar baseline characteristics. Among them, 50% (54/108) were diagnosed with IDC-P, with 22.2% (12/54) having IDC-P pattern 1 and 77.8% (42/54) with IDC-P pattern 2. While no notable difference was seen in PSA responses between IDC-P positive and negative patients, IDC-P presence linked to worse clinical outcomes (PSA-PFS: 18.6 months vs. not reached [NR], p = 0.009; rPFS: 23.6 months vs. NR, p = 0.020). Further analysis showed comparable outcomes for IDC-P pattern 1 but significantly worse prognosis for IDC-P pattern 2 (PSA-PFS: 18.6 months vs. NR, p = 0.002; rPFS: 22.4 months vs. NR, p = 0.010). Subgroup analysis revealed IDC-P pattern 2 consistently predicted poorer outcomes across patient subgroups. Remarkably, both IDC-P positive and negative patients gained more from androgen deprivation therapy with abiraterone than conventional treatment, with IDC-P negative patients showing a more significant survival advantage, supported by better hazard ratios (0.47 and 0.66).

CONCLUSION

This study found that IDC-P, especially pattern 2, predicts poor prognosis in mHSPC patients on abiraterone therapy. Also, abiraterone's advantage over hormone therapy is reduced in cases with IDC-P compared to those without.

Distinct patterns of biomarker expression for atypical intraductal proliferations in prostate cancer

High-grade prostatic intraepithelial neoplasia (HGPIN) is a well-characterised precursor lesion in prostate cancer. The term atypical intraductal proliferations (AIP) describes lesions with features that are far too atypical to be considered HGPIN, yet insufficient to be diagnosed as intraductal carcinoma of the prostate (IDCP). Here, a panel of biomarkers was assessed to provide insights into the biological relationship between IDCP, HGPIN, and AIP and their relevance to current clinicopathological recommendations. Tissue samples from 86 patients with prostate cancer were assessed by routine haematoxylin and eosin staining and immunohistochemistry (IHC) with a biomarker panel (Appl1/Sortilin/Syndecan-1) and a PIN4 cocktail (34βE12+P63/P504S). Appl1 strongly labelled atypical secretory cells, effectively visualising intraductal lesions. Sortilin labelling was moderate-to-strong in > 70% of cases, while Syndecan-1 was moderate-to-strong in micropapillary HGPIN/AIP lesions (83% cases) versus flat/tufting HGPIN (≤ 20% cases). Distinct biomarker labelling patterns for atypical intraductal lesions of the prostate were observed, including early atypical changes (flat/tufting HGPIN) and more advanced atypical changes (micropapillary HGPIN/AIP). Furthermore, the biomarker panel may be used as a tool to overcome the diagnostic uncertainty surrounding AIP by supporting a definitive diagnosis of IDCP for such lesions displaying the same biomarker pattern as cribriform IDCP.

Contemporary Diagnostic Reporting for Prostatic Adenocarcinoma: Morphologic Aspects, Molecular Correlates, and Management Perspectives

The diagnosis and reporting of prostatic adenocarcinoma have evolved from the classic framework promulgated by Dr Donald Gleason in the 1960s into a complex and nuanced system of grading and reporting that nonetheless retains the essence of his remarkable observations. The criteria for the "Gleason patterns" originally proposed have been continually refined by consensuses in the field, and Gleason scores have been stratified into a patient-friendly set of prognostically validated and widely adopted Grade Groups. One product of this successful grading approach has been the opportunity for pathologists to report diagnoses that signal carefully personalized management, placing the surgical pathologist's interpretation at the center of patient care. At one end of the continuum of disease aggressiveness, personalized diagnostic care means to sub-stratify patients with more indolent disease for active surveillance, while at the other end of the continuum, reporting histologic markers signaling aggression allows sub-stratification of clinically significant disease. Whether contemporary reporting parameters represent deeper nuances of more established ones (eg, new criteria and/or quantitation of Gleason patterns 4 and 5) or represent additional features reported alongside grade (intraductal carcinoma, cribriform patterns of carcinoma), assessment and grading have become more complex and demanding. Herein, we explore these newer reporting parameters, highlighting the state of knowledge regarding morphologic, molecular, and management aspects. Emphasis is made on the increasing value and stakes of histopathologists' interpretations and reporting into current clinical risk stratification and treatment guidelines.

Recent insights on the clinical, pathological, and molecular features of intraductal carcinoma of the prostate

Intraductal carcinoma of the prostate, a unique histopathologic entity that is often observed (especially in advanced prostate cancer), is characterized by the proliferation of malignant cells within normal acini or ducts surrounded by a basement membrane. Intraductal carcinoma of the prostate is almost invariably associated with an adjacent high-grade carcinoma and is occasionally observed as an isolated subtype. Intraductal carcinoma of the prostate has been demonstrated to be an independent poor prognostic factor for all stages of cancer, whether localized, de novo metastatic, or castration-resistant. It also has a characteristic genetic profile, including high genomic instability. Recognizing and differentiating it from other pathologies is therefore important in patient management, and morphological diagnostic criteria for intraductal carcinoma of the prostate have been established. This review summarizes and outlines the clinical and pathological features, differential diagnosis, molecular aspects, and management of intraductal carcinoma of the prostate, as described in previous studies. We also present a discussion and future perspectives regarding intraductal carcinoma of the prostate.

PTEN loss in intraductal carcinoma of the prostate has low incidence in Japanese patients

Clinical and genomic features of prostate cancer (PCa) vary considerably between Asian and Western populations. PTEN loss is the most frequent abnormality in intraductal carcinoma of the prostate (IDC-P) in Western populations. However, its prevalence and significance in Asian populations have not yet been well studied. In the present study, we evaluated PTEN expression in IDC-P in a Japanese population and its association with ERG expression. This study included 45 and 59 patients with PCa with and without IDC-P, respectively, who underwent radical prostatectomy. PTEN loss was observed in 10 patients with PCa with IDC-P (22%) and nine patients with PCa without IDC-P (17%). ERG expression was relatively frequent in patients with PCa with PTEN loss, although a significant difference was not observed. The co-occurrence of PTEN loss and ERG expression was observed in four patients with PCa with IDC-P and one without IDC-P. PTEN loss and ERG expression did not affect progression-free survival, regardless of the presence of IDC-P. The frequency of PTEN loss in IDC-P is lower in Asian patients than in Western patients. Our results indicate that mechanisms underlying IDC-P in Asian populations are different from those of Western populations.

Prostatın benign, prekürsör ve malign epitelyal proliferasyonlarında ERG ile PTEN ekspresyonlarının araştırılması ve bulguların klinikopatolojik korelasyonu

Amaç: Prostat kanseri farklı klinik gidişata ve geniş bir tedavi yelpazesine sahip, klinik ve moleküler olarak oldukça heterojen bir kanser türüdür. Özellikle “prostatik intraepitelyal neoplazi” (PİN), “atipik intraduktal proliferasyon” (AİP) ve “intraduktal karsinom” (İDK) benzer morfolojik özelliklere sahip olması açısından ayırıcı tanı zorluğu yaratan tanılar olup, hasta tedavi ve takibi de farklı olan antitelerdir. Çalışmamızda bu lezyonlarda ERG ve PTEN ekspresyon düzeylerini belirlemeyi ve bu biyobelirteçlerin prognostik ve diagnostik değerini araştırmayı amaçladık. Gereç ve Yöntem: EÜTF Tıbbi Patoloji Anabilim Dalında 2011-2012 yılında radikal prostatektomi veya iğne biyopsi materyallerinde “Adenokarsinom” tanısı almış 87 olgu çalışmaya alındı. Histopatolojik olarak AİP, İDK ve PİN içeren alanlar belirlendi. immunohistokimyasal olarak bu alanlarda ERG ve PTEN ekspresyonları değerlendirildi.Bulgular: Olguların 6’sında İDK, 29’unda AİP ve 52’sinde PİN belirlendi. İDK AİP, DG 3 ve üstünde olan tümörlerde daha fazla görüldü. İDK ve AİP in eşlik ettiği prostat karsinomlarının sağ kalım süresi daha kısaydı (p=0.043). İDK ve AİP içeren tümörlerde ERG ve PTEN durumu invaziv komponentle uyum içindeydi. Ayrıca tüm İDK alanlarında ERG pozitifti. PTEN ile heterojen boyanma görülmüş olup, PTEN’in invaziv karsinom ve İDK alanlarında negatifliği daha fazlaydı (p=0,63). ERG pozitifliği ve PTEN negatifliği istatistiksel olarak anlamlı olmamakla birlikte AİP tanısını desteklediği dikkati çekti.Sonuç: Özellikle ayırıcı tanı sorunu yaratan intraduktal lezyonlarda ERG pozitifliği ve PTEN negatifliği klinik öneme sahip prostat karsinomuna eşlik edebileceği için özellikle biyopsilerde gözardı edilmemeli ve hasta tedavi ile takibi buna göre yapılmalıdır.  

Cribriform Lesions of the Prostate Gland

"Cribriform lesions of the prostate represent an important and often diagnostically challenging spectrum of prostate pathology. These lesions range from normal anatomical variation, benign proliferative lesions, premalignant, suspicious to frankly malignant and biologically aggressive entities. The concept of cribriform prostate adenocarcinoma (CrP4) and intraductal carcinoma of the prostate (IDC-P), in particular, has evolved significantly in recent years with a growing body of evidence suggesting that the presence of these morphologies is important for clinical decision-making in prostate cancer management. Therefore, accurate recognition and reporting of CrP4 and IDC-P architecture are especially important. This review discusses a contemporary diagnostic approach to cribriform lesions of the prostate with a focus on their key morphologic features, differential diagnosis, underlying molecular alterations, clinical significance, and reporting recommendations."

The 2022 World Health Organization Classification of Tumors of the Urinary System and Male Genital Organs-Part B: Prostate and Urinary Tract Tumors

The 2022 World Health Organization (WHO) classification of the urinary and male genital tumors was recently published by the International Agency for Research on Cancer. This fifth edition of the WHO "Blue Book" offers a comprehensive update on the terminology, epidemiology, pathogenesis, histopathology, diagnostic molecular pathology, and prognostic and predictive progress in genitourinary tumors. In this review, the editors of the fifth series volume on urologic and male genital neoplasms present a summary of the salient changes introduced to the classification of tumors of the prostate and the urinary tract.

WHO Classification of Tumours fifth edition: evolving issues in the classification, diagnosis, and prognostication of prostate cancer

The fifth edition of the WHO Classification of Tumours of the Urinary and Male Genital Systems encompasses several updates to the classification and diagnosis of prostatic carcinoma as well as incorporating advancements in the assessment of its prognosis, including recent grading modifications. Some of the salient aspects include: (1) recognition that prostatic intraepithelial neoplasia (PIN)-like carcinoma is not synonymous with a pattern of ductal carcinoma, but better classified as a subtype of acinar adenocarcinoma; (2) a specific section on treatment-related neuroendocrine prostatic carcinoma in view of the tight correlation between androgen deprivation therapy and the development of prostatic carcinoma with neuroendocrine morphology, and the emerging data on lineage plasticity; (3) a terminology change of basal cell carcinoma to "adenoid cystic (basal cell) cell carcinoma" given the presence of an underlying MYB::NFIB gene fusion in many cases; (4) discussion of the current issues in the grading of acinar adenocarcinoma and the prognostic significance of cribriform growth patterns; and (5) more detailed coverage of intraductal carcinoma of prostate (IDC-P) reflecting our increased knowledge of this entity, while recommending the descriptive term atypical intraductal proliferation (AIP) for lesions falling short of IDC-P but containing more atypia than typically seen in high-grade prostatic intraepithelial neoplasia (HGPIN). Lesions previously regarded as cribriform patterns of HGPIN are now included in the AIP category. This review discusses these developments, summarising the existing literature, as well as the emerging morphological and molecular data that underpins the classification and prognostication of prostatic carcinoma.

Cribriform Patterned Lesions in the Prostate Gland with Emphasis on Differential Diagnosis and Clinical Significance

Simple Summary

A cribriform structure is defined as a continuous proliferation of cells with intermingled lumina. Various entities may have a cribriform morphology within the prostate gland, ranging from normal, to benign, to borderline and even to malignant lesions. This review summarizes the morphologic features of entities that have a cribriform morphology within the prostate gland, with an emphasis on their differential diagnosis, molecular profile and clinical significance. The basic aim is to assist the pathologist with challenging and controversial cases and inform the clinician on the clinical implications of cribriform morphology.

Abstract

Cribriform glandular formations are characterized by a continuous proliferation of cells with intermingled lumina and can constitute a major or minor part of physiologic (normal central zone glands), benign (clear cell cribriform hyperplasia and basal cell hyperplasia), premalignant (high-grade prostatic intraepithelial neoplasia), borderline (atypical intraductal cribriform proliferation) or clearly malignant (intraductal, acinar, ductal and basal cell carcinoma) lesions. Each displays a different clinical course and variability in clinical management and prognosis. The aim of this review is to summarize the current knowledge regarding the morphological features, differential diagnosis, molecular profile and clinical significance of the cribriform-patterned entities of the prostate gland. Areas of controversy regarding their management, i.e., the grading of Intaductal Carcinoma, will also be discussed. Understanding the distinct nature of each cribriform lesion leads to the correct diagnosis and ensures accuracy in clinical decision-making, prognosis prediction and personalized risk stratification of patients.

Intraductal Carcinoma of the Prostate as a Cause of Prostate Cancer Metastasis: A Molecular Portrait

Intraductal carcinoma of the prostate (IDC-P) is one of the most aggressive types of prostate cancer (PCa). IDC-P is identified in approximately 20% of PCa patients and is associated with recurrence, metastasis, and PCa-specific death. The main feature of this histological variant is the colonization of benign glands by PCa cells. Although IDC-P is a well-recognized independent parameter for metastasis, mechanisms by which IDC-P cells can spread and colonize other tissues are not fully known. In this review, we discuss the molecular portraits of IDC-P determined by immunohistochemistry and genomic approaches and highlight the areas in which more research is needed.

Prostate Pathology: What is New in the 2022 WHO Classification of Urinary and Male Genital Tumors?

In 2022, after a six-year interval, the International Agency for Research on Cancer (IARC) has published the 5th edition of the WHO Classification of Urinary and Male Genital Tumors, which provides a comprehensive update on tumor classification of the genitourinary system. This review article focuses on prostate carcinoma and underscores changes in the prostate chapter as well as those made across the entire series of the 5th edition of WHO Blue Books. Although no major alterations were made to this chapter, some of the most notable updates include restructure of contents and introduction of a new format; standardization of mitotic counts, genomic nomenclatures, and units of length; refined definition for the terms "variant", "subtype", and "histologic pattern"; reclassification of prostatic intraepithelial neoplasia (PIN)-like adenocarcinoma as a subtype of prostatic acinar adenocarcinoma; and recognition of treatment-related neuroendocrine prostatic carcinoma as a distinct tumor type. Evolving and unsettled issues related to grading of intraductal carcinoma of the prostate and reporting of tertiary Gleason pattern, the definition and prognostic significance of cribriform growth pattern, and molecular pathology of prostate cancer will also be covered in this review.

Intraductal Carcinoma of the Prostate: A Guide for the Practicing Pathologist

Intraductal carcinoma of the prostate gland (IDCP) is characterized by an expansile, architecturally, and cytologically atypical proliferation of prostatic epithelial cells within preexisting prostatic ducts and acini. There has been a wider recognition of IDCP by practicing pathologists since its recognition as a separate category in the World Health Organization (WHO) 2016 classification of tumours of the prostate gland. However, there is also a lack of clarity regarding the diagnosis and reporting of IDCP, which has been compounded by divergent expert recommendations regarding the grading of invasive prostate cancers associated with an intraductal component. The International Society of Urological Pathologists (ISUP) recommends that the IDCP component should be incorporated into the Gleason score, while the Genitourinary Pathology Society (GUPS) recommends excluding it when grading prostate cancer. This review seeks to clarify some of these issues and outline a pragmatic approach to reporting IDCP, particularly in needle biopsies. Diagnostic issues and terminology for lesions falling short of IDCP but exceeding that of high-grade prostatic intraepithelial neoplasia are discussed. The management of patients whose prostate biopsies show only IDCP without an associated invasive component is controversial. Some experts recommend radical therapy, while others recommend prompt repeat biopsy. An alternative clinicopathologic approach that takes into consideration the extent, histomorphology, and location (with respect to a radiologic abnormality) of IDCP, as well as radiologic features, is outlined.

Knowing what's growing: Why ductal and intraductal prostate cancer matter

Prostate cancer is a common malignancy, but only some tumors are lethal. Accurately identifying these tumors will improve clinical practice and instruct research. Aggressive cancers often have distinctive pathologies, including intraductal carcinoma of the prostate (IDC-P) and ductal adenocarcinoma. Here, we review the importance of these pathologies because they are often overlooked, especially in genomics and preclinical testing. Pathology, genomics, and patient-derived models show that IDC-P and ductal adenocarcinoma accompany multiple markers of poor prognosis. Consequently, "knowing what is growing" will help translate preclinical research to pinpoint and treat high-risk prostate cancer in the clinic.

The 2019 Genitourinary Pathology Society (GUPS) White Paper on Contemporary Grading of Prostate Cancer

CONTEXT.—

Controversies and uncertainty persist in prostate cancer grading.

OBJECTIVE.—

To update grading recommendations.

DATA SOURCES.—

Critical review of the literature along with pathology and clinician surveys.

CONCLUSIONS.—

Percent Gleason pattern 4 (%GP4) is as follows: (1) report %GP4 in needle biopsy with Grade Groups (GrGp) 2 and 3, and in needle biopsy on other parts (jars) of lower grade in cases with at least 1 part showing Gleason score (GS) 4 + 4 = 8; and (2) report %GP4: less than 5% or less than 10% and 10% increments thereafter. Tertiary grade patterns are as follows: (1) replace "tertiary grade pattern" in radical prostatectomy (RP) with "minor tertiary pattern 5 (TP5)," and only use in RP with GrGp 2 or 3 with less than 5% Gleason pattern 5; and (2) minor TP5 is noted along with the GS, with the GrGp based on the GS. Global score and magnetic resonance imaging (MRI)-targeted biopsies are as follows: (1) when multiple undesignated cores are taken from a single MRI-targeted lesion, an overall grade for that lesion is given as if all the involved cores were one long core; and (2) if providing a global score, when different scores are found in the standard and the MRI-targeted biopsy, give a single global score (factoring both the systematic standard and the MRI-targeted positive cores). Grade Groups are as follows: (1) Grade Groups (GrGp) is the terminology adopted by major world organizations; and (2) retain GS 3 + 5 = 8 in GrGp 4. Cribriform carcinoma is as follows: (1) report the presence or absence of cribriform glands in biopsy and RP with Gleason pattern 4 carcinoma. Intraductal carcinoma (IDC-P) is as follows: (1) report IDC-P in biopsy and RP; (2) use criteria based on dense cribriform glands (>50% of the gland is composed of epithelium relative to luminal spaces) and/or solid nests and/or marked pleomorphism/necrosis; (3) it is not necessary to perform basal cell immunostains on biopsy and RP to identify IDC-P if the results would not change the overall (highest) GS/GrGp part per case; (4) do not include IDC-P in determining the final GS/GrGp on biopsy and/or RP; and (5) "atypical intraductal proliferation (AIP)" is preferred for an intraductal proliferation of prostatic secretory cells which shows a greater degree of architectural complexity and/or cytological atypia than typical high-grade prostatic intraepithelial neoplasia, yet falling short of the strict diagnostic threshold for IDC-P. Molecular testing is as follows: (1) Ki67 is not ready for routine clinical use; (2) additional studies of active surveillance cohorts are needed to establish the utility of PTEN in this setting; and (3) dedicated studies of RNA-based assays in active surveillance populations are needed to substantiate the utility of these expensive tests in this setting. Artificial intelligence and novel grading schema are as follows: (1) incorporating reactive stromal grade, percent GP4, minor tertiary GP5, and cribriform/intraductal carcinoma are not ready for adoption in current practice.

Intraductal Carcinoma of the Prostate: Pathogenesis and Molecular Perspectives

Intraductal carcinoma of the prostate (IDC-P), a clinicopathological entity characterized by malignant prostatic epithelial cells growing within ducts and/or acini, has a distinct architectural pattern, cytological features, and biological behavior. Whereas most IDC-P tumors could be derived from adjacent high-grade invasive cancer via retrograde spreading of cancer cells along benign ducts and acini, a small subset of IDC-P may arise from the transformation and intraductal proliferation of precancerous cells induced by various oncogenic events. These isolated IDC-P tumors possess a distinct mutational profile and may function as a carcinoma in situ lesion with de novo intraductal outgrowth of malignant cells. Further molecular characterization of these two types of IDC-P and better understanding of the mechanisms underlying IDC-P formation and progression could be translated into valuable biomarkers for differential diagnosis and actionable targets for therapeutic interventions. PATIENT SUMMARY: Intraductal carcinoma of the prostate is an aggressive type of prostate cancer associated with high risk for local recurrence and distant metastasis. In this review, we discussed pathogenesis, biomarkers, differential diagnoses, and therapeutic strategies for this tumor.

Head to head: should the intraductal component of invasive prostate cancer be graded?

The reporting of intraductal carcinoma of the prostate (IDCP) is controversial, with conflicting recommendations having recently been published by the International Society of Urological Pathology (ISUP) and the Genitourinary Pathology Society (GUPS). Both recommend that isolated (pure) IDCP should not be graded. However, the ISUP recommends incorporating the IDCP component of invasive prostate cancer in the Gleason score, whereas the GUPS recommends reporting IDCP as a comment, independently of the Gleason score. The arguments for and against incorporating the IDCP component of invasive prostate cancer in the Gleason score are discussed in detail.

Identification of intraductal carcinoma of the prostate on tissue specimens using Raman micro-spectroscopy: A diagnostic accuracy case-control study with multicohort validation

BACKGROUND

Prostate cancer (PC) is the most frequently diagnosed cancer in North American men. Pathologists are in critical need of accurate biomarkers to characterize PC, particularly to confirm the presence of intraductal carcinoma of the prostate (IDC-P), an aggressive histopathological variant for which therapeutic options are now available. Our aim was to identify IDC-P with Raman micro-spectroscopy (RμS) and machine learning technology following a protocol suitable for routine clinical histopathology laboratories.

METHODS AND FINDINGS

We used RμS to differentiate IDC-P from PC, as well as PC and IDC-P from benign tissue on formalin-fixed paraffin-embedded first-line radical prostatectomy specimens (embedded in tissue microarrays [TMAs]) from 483 patients treated in 3 Canadian institutions between 1993 and 2013. The main measures were the presence or absence of IDC-P and of PC, regardless of the clinical outcomes. The median age at radical prostatectomy was 62 years. Most of the specimens from the first cohort (Centre hospitalier de l'Université de Montréal) were of Gleason score 3 + 3 = 6 (51%) while most of the specimens from the 2 other cohorts (University Health Network and Centre hospitalier universitaire de Québec-Université Laval) were of Gleason score 3 + 4 = 7 (51% and 52%, respectively). Most of the 483 patients were pT2 stage (44%-69%), and pT3a (22%-49%) was more frequent than pT3b (9%-12%). To investigate the prostate tissue of each patient, 2 consecutive sections of each TMA block were cut. The first section was transferred onto a glass slide to perform immunohistochemistry with H&E counterstaining for cell identification. The second section was placed on an aluminum slide, dewaxed, and then used to acquire an average of 7 Raman spectra per specimen (between 4 and 24 Raman spectra, 4 acquisitions/TMA core). Raman spectra of each cell type were then analyzed to retrieve tissue-specific molecular information and to generate classification models using machine learning technology. Models were trained and cross-validated using data from 1 institution. Accuracy, sensitivity, and specificity were 87% ± 5%, 86% ± 6%, and 89% ± 8%, respectively, to differentiate PC from benign tissue, and 95% ± 2%, 96% ± 4%, and 94% ± 2%, respectively, to differentiate IDC-P from PC. The trained models were then tested on Raman spectra from 2 independent institutions, reaching accuracies, sensitivities, and specificities of 84% and 86%, 84% and 87%, and 81% and 82%, respectively, to diagnose PC, and of 85% and 91%, 85% and 88%, and 86% and 93%, respectively, for the identification of IDC-P. IDC-P could further be differentiated from high-grade prostatic intraepithelial neoplasia (HGPIN), a pre-malignant intraductal proliferation that can be mistaken as IDC-P, with accuracies, sensitivities, and specificities > 95% in both training and testing cohorts. As we used stringent criteria to diagnose IDC-P, the main limitation of our study is the exclusion of borderline, difficult-to-classify lesions from our datasets.

CONCLUSIONS

In this study, we developed classification models for the analysis of RμS data to differentiate IDC-P, PC, and benign tissue, including HGPIN. RμS could be a next-generation histopathological technique used to reinforce the identification of high-risk PC patients and lead to more precise diagnosis of IDC-P.

Isolated Intraductal Carcinoma of the Prostate in Prostatectomy Specimens: Report of 2 Cases and Review of the Literature

Intraductal carcinoma of the prostate (IDCp) is a distinct neoplastic entity, and although recognized for some time, it was included for the first time in the histologic classification of prostate cancer in the 2016 publication of World Health Organization. IDCp represents an intraductal or intra-acinar proliferation of malignant cells, with preservation of the basal cell layer. Even though IDCp is usually accompanied by a high-grade invasive component, low-grade invasive carcinoma can rarely be seen adjacent to the lesion. Even rarer is the incidence of isolated IDCp in needle biopsies, while a few such cases have been reported in prostatectomy specimens. We report 2 cases with isolated IDCp without any invasive component. A review of the literature is performed including the diagnostic challenges of IDCp and its morphologic mimics, immunohistochemical markers, molecular aspects, and prognostic implications. Even though it is not yet clear whether IDCp represents an intraductal spread of invasive cancer or a precursor of invasive carcinoma, the existence of isolated IDCp reinforces the idea that, at least in some of the cases, IDCp is a precancerous lesion. Further molecular studies need to be performed in order to clarify its pathogenesis.

PTEN loss in prostatic adenocarcinoma correlates with specific adverse histologic features (intraductal carcinoma, cribriform Gleason pattern 4 and stromogenic carcinoma)

BACKGROUND

The loss of PTEN tumor suppressor gene is one of the most common somatic genetic aberrations in prostate cancer (PCa) and is frequently associated with high-risk disease. Deletion or mutation of at least one PTEN allele has been reported to occur in 20% to 40% of localized PCa and up to 60% of metastases. The goal of this study was to determine if somatic alteration detected by PTEN immunohistochemical loss of expression is associated with specific histologic features.

METHODS

Two hundred sixty prostate core needle biopsies with PCa were assessed for PTEN loss using an analytically validated immunohistochemical assay. Blinded to PTEN status, each tumor was assessed for the Grade Group (GG) and the presence or absence of nine epithelial features. Presence of stromogenic PCa was also assessed and defined as grade 3 reactive tumor stroma as previously described: the presence of carcinoma associated stromal response with epithelial to stroma ratio of greater than 50% reactive stroma.

RESULTS

Eight-eight (34%) cases exhibited PTEN loss while 172 (66%) had intact PTEN. PTEN loss was significantly (P < 0.05) associated with increasing GG, poorly formed glands (74% of total cases with loss vs 49% of intact), and three well-validated unfavorable pathological features: intraductal carcinoma of the prostate (IDC-P) (69% of total cases with loss vs 12% of intact), cribriform Gleason pattern 4 (38% of total cases with loss vs 10% of intact) and stromogenic PCa (23% of total cases with loss vs 6% of intact). IDC-P had the highest relative risk (4.993, 95% confidence interval, 3.451-7.223, P < 0.001) for PTEN loss. At least one of these three unfavorable pathological features were present in 67% of PCa exhibiting PTEN loss, while only 11% of PCa exhibited PTEN loss when none of these three unfavorable pathological features were present.

CONCLUSIONS

PCa with PTEN loss demonstrates a strong correlation with known unfavorable histologic features, particularly IDC-P. This is the first study showing the association of PTEN loss with stromogenic PCa.

[Grading of prostate cancer. For a more precise prognosis]

The simplification of the Gleason grading system, together with the reclassification of some of its patterns, has improved correlation with the clinical reality of prostate cancer, whilst maintaining the basic principles established fifty years ago. The subsequent grouping of the patterns into five degrees has allowed a more rational unification and enhanced the physician/patient communication. However, a greater precision in the assessment of the prognosis for each patient is still necessary and, to this end, elements that allow greater discrimination are continually being sought. The purpose of this brief review is to discuss the value and possible future incorporation in international recommendations of the percentage of pattern 4, the quantification of the cribriform pattern, the detection of intraductal carcinoma, the regrouping of some 'scores' and the possible stratification of the grade group 1.

Intraductal carcinoma of the prostate: a critical re-appraisal

Intraductal carcinoma of the prostate gland (IDCP), which is now categorised as a distinct entity by WHO 2016, includes two biologically distinct diseases. IDCP associated with invasive carcinoma (IDCP-inv) generally represents a growth pattern of invasive prostatic adenocarcinoma while the rarely encountered pure IDCP is a precursor of prostate cancer. This review highlights issues that require further discussion and clarification. The diagnostic criterion “nuclear size at least 6 times normal” is ambiguous as “size” could refer to either nuclear area or diameter. If area, then this criterion could be re-defined as nuclear diameter at least three times normal as it is difficult to visually compare area of nuclei. It is also unclear whether IDCP could also include tumours with ductal morphology. There is no consensus whether pure IDCP in needle biopsies should be managed with re-biopsy or radical therapy. A pragmatic approach would be to recommend radical therapy only for extensive pure IDCP that is morphologically unequivocal for high-grade prostate cancer. Active surveillance is not appropriate when low-grade invasive cancer is associated with IDCP, as such patients usually have unsampled high-grade prostatic adenocarcinoma. It is generally recommended that IDCP component of IDCP-inv should be included in tumour extent but not grade. However, there are good arguments in favour of grading IDCP associated with invasive cancer. All historical as well as contemporary Gleason outcome data are based on morphology and would have included an associated IDCP component in the tumour grade. WHO 2016 recommends that IDCP should not be graded, but it is unclear whether this applies to both pure IDCP and IDCP-inv.

Large-Gland Proliferations of the Prostate

Large-gland proliferations of the prostate have gained considerable attention in the past decade. The differential diagnosis is quite broad but can be refined using histologic criteria and, sometimes, immunostains. Pathologists have come to realize that cribriform and intraductal as well as ductal carcinomas are particularly aggressive patterns, and should name them in diagnostic reporting when present.

Molecular Biomarkers in the Clinical Management of Prostate Cancer

Prostate cancer, one of the most common noncutaneous malignancies in men, is a heterogeneous disease with variable clinical outcome. Although the majority of patients harbor indolent tumors that are essentially cured by local therapy, subsets of patients present with aggressive disease or recur/progress after primary treatment. With this in mind, modern clinical approaches to prostate cancer emphasize the need to reduce overdiagnosis and overtreatment via personalized medicine. Advances in our understanding of prostate cancer pathogenesis, coupled with recent technologic innovations, have facilitated the development and validation of numerous molecular biomarkers, representing a range of macromolecules assayed from a variety of patient sample types, to help guide the clinical management of prostate cancer, including early detection, diagnosis, prognostication, and targeted therapeutic selection. Herein, we review the current state of the art regarding prostate cancer molecular biomarkers, emphasizing those with demonstrated utility in clinical practice.

Spectrum of Cribriform Proliferations of the Prostate: From Benign to Malignant

Context.—

The presence of cribriform glands/ducts in the prostate can pose a diagnostic challenge. Cribriform glands/ducts include a spectrum of lesions, from benign to malignant, with vastly different clinical, prognostic, and treatment implications.

Objective.—

To highlight the diagnostic features of several entities with a common theme of cribriform architecture. We emphasize the importance of distinguishing among benign entities such as cribriform changes and premalignant to malignant entities such as high-grade prostatic intraepithelial neoplasia, atypical intraductal cribriform proliferation, intraductal carcinoma of the prostate, and invasive adenocarcinoma (acinar and ductal types). The diagnostic criteria, differential diagnosis, and clinical implications of these cribriform lesions are discussed.

Data Sources.—

Literature review of pertinent publications in PubMed up to calendar year 2017. Photomicrographs obtained from cases at the University of California at Irvine and authors' collections.

Conclusions.—

Although relatively uncommon compared with small acinar lesions (microacinar carcinoma and small gland carcinoma mimickers), large cribriform lesions are increasingly recognized and have become clinically and pathologically important. The spectrum of cribriform lesions includes benign, premalignant, and malignant lesions, and differentiating them can often be subtle and difficult. Intraductal carcinoma of the prostate in particular is independently associated with worse prognosis, and its presence in isolation should prompt definitive treatment. Patients with atypical intraductal cribriform proliferation, intraductal carcinoma of the prostate, or even focal cribriform pattern of invasive adenocarcinoma in biopsies would not be ideal candidates for active surveillance because of the high risk of adverse pathologic findings associated with these entities.

Clinical implications of PTEN loss in prostate cancer

Genomic aberrations of the PTEN tumour suppressor gene are among the most common in prostate cancer. Inactivation of PTEN by deletion or mutation is identified in ∼20% of primary prostate tumour samples at radical prostatectomy and in as many as 50% of castration-resistant tumours. Loss of phosphatase and tensin homologue (PTEN) function leads to activation of the PI3K-AKT (phosphoinositide 3-kinase-RAC-alpha serine/threonine-protein kinase) pathway and is strongly associated with adverse oncological outcomes, making PTEN a potentially useful genomic marker to distinguish indolent from aggressive disease in patients with clinically localized tumours. At the other end of the disease spectrum, therapeutic compounds targeting nodes in the PI3K-AKT-mTOR (mechanistic target of rapamycin) signalling pathway are being tested in clinical trials for patients with metastatic castration-resistant prostate cancer. Knowledge of PTEN status might be helpful to identify patients who are more likely to benefit from these therapies. To enable the use of PTEN status as a prognostic and predictive biomarker, analytically validated assays have been developed for reliable and reproducible detection of PTEN loss in tumour tissue and in blood liquid biopsies. The use of clinical-grade assays in tumour tissue has shown a robust correlation between loss of PTEN and its protein as well as a strong association between PTEN loss and adverse pathological features and oncological outcomes. In advanced disease, assessing PTEN status in liquid biopsies shows promise in predicting response to targeted therapy. Finally, studies have shown that PTEN might have additional functions that are independent of the PI3K-AKT pathway, including those affecting tumour growth through modulation of the immune response and tumour microenvironment.

The New Realization About Cribriform Prostate Cancer

Data from the past 6 years have shown that the presence of any amount of cribriform (or more comprehensively, large acinar cribriform to papillary) pattern of invasive prostate cancer is associated with adverse pathologic features and leads to uniquely adverse outcomes. Sixteen papers and numerous abstracts have reached these conclusions concordantly. Not only does this justify removal of all cribriform cancer from Gleason grade 3, it shows that cribriform cancer has pathologic, outcome, and molecular features distinct from noncribriform Gleason grade 4. Suggestions for accommodating the presence of cribriform cancer into the 2014 Grade Group scheme are proposed.

High-grade prostatic intraepithelial neoplasia, PIN-like carcinoma, ductal carcinoma, and intraductal carcinoma of the prostate

Many prostate lesions have 'large gland' morphology with gland size similar to or larger than benign glands, complex glandular architecture including papillary, cribriform, and solid, and significant cytological atypia in glandular epithelium with nucleomegaly, prominent nucleoli, or anisonucleosis. The most common and clinically important lesions with 'large gland' morphology include high-grade prostatic intraepithelial neoplasia (HGPIN), PIN-like carcinoma, ductal adenocarcinoma, and intraductal carcinoma. These lesions have diverse clinical significance and management implications. HGPIN refers to proliferation of glandular epithelium that displays severe cytological atypia within the confines of prostatic ducts and acini. A HGPIN diagnosis in biopsies connotes ~25% risk of detection of cancer in repeat biopsies. It has been accepted as the main precursor lesion to invasive carcinoma. PIN-like carcinoma is a variant of acinar carcinoma that is morphologically reminiscent of HGPIN and is composed of large cancer glands lined with pseudostratified epithelium. Its clinical outcome is similar to that of usual acinar carcinomas and is graded as Gleason score 3+3=6. Ductal adenocarcinoma comprises large glands lined with tall columnar and pseudostratified epithelium. It is more aggressive than acinar carcinomas and is associated with higher stage disease and greater risk of PSA recurrence and mortality. Intraductal carcinoma is an intraglandular/ductal neoplastic proliferation of glandular epithelial cells that results in marked expansion of glandular architecture and nuclear atypia that often exceeds that in invasive carcinomas. In majority of cases, it is thought to represent retrograde extension of invasive carcinoma into pre-existing ducts and acini. Rarely it may represent a peculiar form of carcinoma with predilection for intraductal location. It is considered an adverse pathological feature and is seen almost always in high-grade and volume carcinoma and harbingers worse clinical outcomes. This article reviews 'new' information on the clinical and pathological features of HGPIN, PIN-like carcinoma, ductal carcinoma, and intraductal carcinoma, and focuses morphological features that aid the differential diagnosis.