Distribution pattern of basal cells detected by cytokeratin 34 beta E12 in primary prostatic duct adenocarcinoma

Intraductal Adenocarcinoma of the Prostate With Cribriform or Papillary Ductal Morphology: Rare Biopsy Cases Lacking Associated Invasive High-grade Carcinoma

Prostatic duct adenocarcinoma, characterized by pseudostratified columnar epithelium, has historically been considered invasive carcinoma, although it may commonly have an intraductal component. Usual (acinar) intraductal carcinoma of the prostate (IDC-P) is a noninvasive high-risk lesion typically associated with high-grade, high-stage prostate cancer. Whereas there have been rare biopsy studies of pure acinar IDC-P or IDC-P associated with only low-grade carcinoma, there have been no analogous series of IDC-P with cribriform or papillary ductal morphology on biopsy unassociated with invasive high-grade carcinoma. We identified 14 patients with biopsies showing IDC-P with ductal morphology, defined as prostatic duct adenocarcinoma confined to glands/ducts with immunohistochemically proven retention of basal cells. Our series includes 12 patients with pure IDC-P and 2 patients with concurrent low-volume Grade Group 1 invasive cancer in unassociated cores. Three patients underwent radical prostatectomy: 2/3 had high-grade cancer in their resection specimen (Grade Group 3, Grade Group 5), including 1 with advanced stage and nodal metastases; 1/3 had Grade Group 1 organ-confined carcinoma and spatially distinct IDC-P with ductal morphology. Five men had only follow-up biopsies: 2/5 had cancer (Grade Group 2, Grade Group 4); 1/5 had IDC-P (on 2 repeat biopsies); and 2/5 had benign transurethral resection of the prostate. In all 5 cases with invasive cancer, the invasive portion was comprised purely of acinar morphology; no invasive ductal component was identified. Five patients did not have follow-up biopsies and were treated with radiation therapy±androgen deprivation. One patient had no follow-up information. In an analogous situation to acinar IDC-P, we propose that rarely there is a precursor form of ductal adenocarcinoma that can exist without concurrent invasive high-grade carcinoma and propose the term "IDC-P with ductal morphology," consistent with the terminology for acinar prostate adenocarcinoma. Until more evidence is accumulated, we recommend reporting and treating patients with IDC-P with ductal morphology in a manner analogous to those with acinar IDC-P. As with pure IDC-P with acinar morphology, we would also recommend not grading pure IDC-P with ductal morphology. Finally, we propose a new addition to the diagnostic criteria of IDC-P to include intraductal lesions with ductal morphology consisting of papillary fronds or cribriform lesions lined by cytologically atypical pseudostratified epithelium.

Prostatic Duct Carcinoma with Combined Prostatic Duct Adenocarcinoma and Urothelial Carcinoma Features

We report a unique case of prostatic duct carcinoma (PDC) featuring both prostatic duct adenocarcinoma (PDA) and high-grade urothelial carcinoma (HG-UC). An 84-year-old man presenting with hematuria showed at ultrasonography and cystoscopy a papillary neoplasia located near to the verumontanum. Histopathologic examination of specimens from transurethral resection revealed a tumor originating from large prostatic ducts showing 2 different components: PDA with endometrioid features (main pattern) and HG-UC (minor part). Immunohistochemically, the areas of PDA were positive for prostatic acid phosphatase (PAP), prostatic specific antigen (PSA), and androgen receptors (AR), while negative for estrogen (ER) and progesterone receptors (PGR). Prognostic factors evaluation pointed out a low proliferation index (10%) and focal expression of p53 (6%); c-erb-B2 was not overexpressed. The HG-UC areas were negative for all previous markers, while positive for thromobomodulin. The proliferation index was high (60%), and p53 was diffusely expressed (55%). The incidence and significance of PDC with combined features is discussed with reference to literature data.

Immunohistochemical profile of ductal adenocarcinoma of the prostate

Ductal adenocarcinoma of the prostate (DAC) is considered to be an aggressive subtype of prostate cancer with greater risk of progression than acinar adenocarcinoma (AC). It has been debated whether DAC is a distinct subtype or a morphological variant of AC. Our aim was to examine the protein expression of DAC and to compare the results with AC. A tissue microarray was constructed from 60 DAC and 46 AC matched by Gleason score. The slides were stained for 28 immunomarkers (estrogen, progesterone and androgen receptor, prolactin, PSA, prostein, PSMA, PSAP, CDX2, lysozyme, villin, monoclonal CEA, CK7, CK20, HMWCK, p63, p504s, c-myc, EGFR, Ki-67, p16, p21, p27, p53, PTEN, ERG, PAX-2, and PAX-8). HMWCK was positive in 8.5 % of DAC, but negative in all cases of AC (p = 0.045). p16 was positive in 53.3 % of DAC and in 26.1 % of AC (p = 0.005). p53 was positive in 42.4 % of DAC and 26.7 % of AC (p = 0.031). A distinct patchy positivity of CK20 was seen in 23.7 % of DAC, and this pattern was also seen in 9.1 % of AC (p = 0.047). Villin was positive in 3.4 % of DAC while expression was negative in AC. Ki-67 labeling index was significantly higher in DAC than in AC (mean 9.2 % [95 % CI 6.4-12.0] and 2.6 % [1.9-3.4], p < 0.001). While there is some overlap in the immunohistochemical expression of DAC and AC, the differences between these two morphotypes of prostatic carcinoma are consistent with DAC having a more aggressive phenotype than AC.

Current significance of the finding of high grade prostatic intraepithelial neoplasia in the prostate biopsy

INTRODUCTION

High grade prostatic intraepithelial neoplasia (HGPIN) is regarded as a precursor of prostate cancer (PC). However, its relationship to cancer has changed throughout the literature, being currently poorly defined and remains controversial for urologists in their clinical practice. Because of his frequency and the impact on patient outcomes that the lack of consensus clinical attitude could carry out, it seems advisable to review the understanding of this disease.

OBJECTIVE

The aim of this literature review is to summarize the main features of this entity (histopathology, molecular, epidemiological) and evaluate their relationship with prostate adenocarcinoma, explaining the variation of incidence seen in the literature and the clinical significance of their finding.

MATERIAL AND METHODS

Review of the literature, based on the research and analysis of publications found in Pubmed with the words "prostate" and "intraepithelial neoplasms".

RESULTS

The HGPIN detection rate has increased to the extent that it has increased the number of punctures in prostate biopsies. With the current biopsy schemes (10-12 punctures), the detection rate of PC in repeat biopsies is similar in patients with and without isolated HGPIN. However, HGPIN multifocality predicts increased risk of PC detection in repeat biopsy.

CONCLUSION

HGPIN detection is common with current biopsy schemes. Its genetic relationship with PC is clear and its multifocality is the most important predictor factor of PC.

Preneoplasia in the prostate gland with emphasis on high grade prostatic intraepithelial neoplasia

There are a variety of morphological patterns and processes that have been implicated in the pathogenesis of prostate cancer. Prostatic intraepithelial neoplasia (PIN), inflammation with or without atrophy, and adenosis (atypical adenomatous hyperplasia) have all been given candidate status as precursor lesions of prostatic adenocarcinoma. Based on decades of research, high grade prostatic intraepithelial neoplasia (HPIN), a proliferative lesion of prostatic secretory cells, has emerged as the most likely morphological pre-invasive lesion involved in the evolution of many but not all prostatic adenocarcinomas. In this manuscript, we briefly discuss other proposed precursors of prostatic adenocarcinoma and then focus on the history, diagnostic criteria and morphology of HPIN. The incidence of HPIN and its relationship to prostate cancer is reviewed. The differential diagnosis of large glandular patterns in the prostate is discussed in depth. Finally, we summarise the recent clinicopathological studies evaluating the clinical significance of HPIN and discuss follow-up strategies in men diagnosed with HPIN.

Histopathological features of ductal adenocarcinoma of the prostate in 1,051 radical prostatectomy specimens

Ductal adenocarcinoma (DAC) of the prostate is thought to have worse prognosis than prostatic acinar carcinoma (PAC). We aimed to evaluate the prognostic significance of histopathological patterns of DAC. A series of 1,051 radical prostatectomy specimens from Karolinska University Hospital 1998-2005 was reviewed. A ductal component was classified as classical DAC (DACC) if it had columnar, pseudostratified epithelium, elongated nuclei, and papillary, glandular, or cribriform architecture; borderline DAC (DACB) if it lacked elongated nuclei or classical architecture; and prostatic adenocarcinoma with ductal features (PCDF) if stratified high-grade nuclei were found. DACC, DACB, and PCDF were seen in 2.6, 4.0, and 1.6 % of the cases. DAC was usually mixed with PAC and constituted 10-100 % (mean 40 %) of the main tumor. Location was periurethral, peripheral, or both in 69.8, 3.5, and 26.7 %. Necrosis was seen in 31.3 %, stromal invasion of DAC in 52.3 %, and intraductal spread in 91.9 %. In DACC/DACB and PAC, extraprostatic extension was seen in 66.7 and 42.4 % (p < 0.001) and seminal vesicle invasion in 13.0 and 5.0 % (p = 0.0045). DACC, DACB, and PCDF had a hazard ratio for biochemical recurrence of 1.5 (0.7-2.8), 1.4 (0.8-2.6) and 1.2 (0.5-2.7). When PCDF was excluded from DAC, hazard ratio was 1.4 (95 % CI 0.9-2.3, p = 0.12). Location, % DAC, necrosis, stromal invasion, or Gleason score were not predictive of recurrence. This suggests that DACC and DACB are more aggressive than average PAC, while cancers with acinar architecture and pseudostratified high-grade nuclei should not be included in DAC.

Study of immunohistochemistry in prostatic lesions with special reference to proliferation and invasiveness

Prostatic lesions on routine staining sometimes cause diagnostic dilemma especially in premalignant lesions like atypical adenomatous hyperplasia and prostatic intraepithelial neoplasia. Benign small acinar lesions also may be difficult to differentiate from small acinar adenocarcinoma. An important differentiating point is the loss of basal cell layer in adenocarcinoma and its presence in benign lesions. Basal cell markers (e.g. 34βE12 cytokeratin) & proliferative markers (e.g. AgNOR and PCNA) can help in this regard. Total 60 cases of different prostatic lesions studied. After history taking, clinical examination, radiological & other investigations were done. Routine H&E staining, immunohistochemical staining against 34βE12 cytokeratin & proliferative markers (AgNOR & PCNA) was performed. Statistically significant differences found in expression of 34βE12 cytokeratin and proliferative markers between benign, premalignant and malignant prostatic lesions. Basal cell markers and proliferative markers are important parameters to distinguish between different benign, premalignant and malignant prostatic lesions.

Gene expression profiles of ductal versus acinar adenocarcinoma of the prostate

Ductal adenocarcinoma is an uncommon variant of prostatic adenocarcinoma with a generally more aggressive clinical course than usual acinar adenocarcinoma. However, the molecular distinction between ductal and acinar adenocarcinomas is not well characterized. The aim of this investigation was to evaluate the relatedness of ductal versus acinar prostatic adenocarcinoma by comparative gene expression profiling. Archived, de-identified, snap frozen tumor tissue from 5 ductal adenocarcinomas, 3 mixed ductal-acinar adenocarcinomas, and 11 acinar adenocarcinomas cases were analyzed. All cases of acinar and ductal adenocarcinomas were matched by Gleason grade. RNA from whole tissue sections of the 5 ductal and 11 acinar adenocarcinomas cases were subjected to gene expression profiling on Affymetrix U133Plus2 microarrays. Independently, laser-capture microdissection was also performed on the three mixed ductal-acinar cases and five pure acinar cases to isolate homogeneous populations of ductal and acinar carcinoma cells from the same tumor. Seven of these laser-capture microdissected samples (three ductal and four acinar cell populations) were similarly analyzed on U133Plus2 arrays. Analysis of data from whole sections of ductal and acinar carcinomas identified only 25 gene transcripts whose expression was significantly and at least two-fold different between ductal and acinar adenocarcinomas. A similar analysis of microdissected cell populations identified 10 transcripts, including the prolactin receptor, with more significant differences in expression of 5- to 27-fold between ductal and acinar adenocarcinomas cells. Overexpression of prolactin receptor protein in ductal versus acinar adenocarcinoma was confirmed by immunohistochemistry in an independent set of tumors. We conclude that ductal and acinar adenocarcinomas of the prostate are strikingly similar at the level of gene expression. However, several of the genes identified in this study, including the prolactin receptor, represent targets for further investigations on the molecular basis for histomorphological and clinical behavioral differences between acinar and ductal adenocarcinomas.

Precursor lesions to prostatic adenocarcinoma

High-grade prostatic intraepithelial neoplasia (PIN) is the one well-documented precursor to adenocarcinoma of the prostate. This review article defines both low- and high-grade PIN. Unusual variants of high-grade PIN are illustrated. Benign lesions that may be confused with high-grade PIN, including central zone histology, clear cell cribriform hyperplasia, and basal cell hyperplasia are described and illustrated. High-grade PIN is also differentiated from invasive acinar (usual) and ductal adenocarcinoma. The incidence of high-grade PIN, its relationship to carcinoma (including molecular findings), and risk of cancer on rebiopsy are covered in detail. Finally, intraductal carcinoma of the prostate, a controversial entity, is discussed and differentiated from high-grade PIN.

Rare and unusual histological variants of prostatic carcinoma: clinical significance

We review the clinicopathological features of the following unusual histological variants of prostatic carcinoma: small cell carcinoma, ductal adenocarcinoma, sarcomatoid (carcinosarcoma), basal cell, squamous cell and adenosquamous, and urothelial carcinoma. These variants are rare and account for 5-10% of carcinomas that originate in the prostate. Some develop from acinar adenocarcinoma after hormonal or radiation therapy. They are usually aggressive tumours that often present with secondary deposits. The outcome is generally poor. Only basal cell carcinoma is seen as a low-grade carcinoma.

Loss of myoepithelium is variable in solid papillary carcinoma of the breast

AIMS

Reports on the frequency of myoepithelial loss in solid papillary carcinoma (SPC) of the breast, an unusual variant of papillary carcinoma with a solid pattern of expansile growth, have been strikingly contradictory. The aim was to clarify the frequency of myoepithelial loss in cases of SPC diagnosed at our institution.

METHODS AND RESULTS

Eleven cases of SPC with available blocks or unstained slides were retrieved from the M. D. Anderson archives or obtained from outside contributors. Immunohistochemistry for smooth muscle actin (SMA) and p63 was evaluated on the circumscribed nests that appeared to be non-invasive by haematoxylin and eosin morphology. Three of the 11 cases (27%) were positive for both SMA and p63 at the periphery of all such foci, whereas eight cases (73%) lacked staining for both myoepithelial markers in at least one focus. Of these eight cases, one was diagnosed with only microinvasion, yet metastatic tumour resembling the circumscribed primary SPC was identified in two ipsilateral axillary lymph nodes.

CONCLUSIONS

SPC of the breast frequently lacks myoepithelial markers at the tumour-stromal interface in spite of a circumscribed non-invasive appearance. Metastases from such tumours are infrequent, but can occur in cases that lack myoepithelial marker expression by immunohistochemistry.

Prostatic ductal adenocarcinoma presenting as a urethral polyp: a clinicopathological study of eight cases of a lesion with the potential to be misdiagnosed as a benign prostatic urethral polyp

AIMS

Centrally located prostatic ductal adenocarcinoma can present as a single urethral polyp mimicking a benign polyp. Such lesions have not been formally studied.

METHODS AND RESULTS

Clinicopathological and immunohistochemical findings of eight cases were analysed. Patients (mean age 76 years) presented with urinary symptoms and haematuria. Mean serum prostate specific antigen (PSA) was 7.01 ng/mL (range 1.04-21). Single small polyps were seen on cystourethroscopy with a clinical diagnosis of benign polyps. The most common architectural patterns were cribriform and papillary. Five cases had mild cytological atypia, three of which were initially diagnosed as benign prostatic urethral polyps. All cases were positive for PSA and 34betaE12. Seven cases tested were positive for AMACR (a-methylacyl-CoA racemase), p63 and cytokeratin (CK) 7 and 70% for CK20. Proliferative activity defined as Ki-67 labelling index was high (mean 26%, range 20-35%). Adenocarcinoma, predominantly ductal, was found in other specimens in four patients.

CONCLUSIONS

Centrally located prostatic ductal adenocarcinoma has the propensity to mimic benign urethral polyps clinically and histopathologically. Basal cell immunostaining may not help with this distinction but AMACR is useful. Prominent glandular complexity including cribriform patterns, nuclear pseudostratification, at least mild atypia and a high Ki-67 index distinguish these lesions from prostatic urethral polyps.

Immunohistochemical Antibody Cocktail Staining (p63/HMWCK/AMACR) of Ductal Adenocarcinoma and Gleason Pattern 4 Cribriform and Noncribriform Acinar Adenocarcinomas of the Prostate

Overexpression of alpha-methylacyl coenzyme A racemase (AMACR) in combination with absence of basal cell markers [ie, p63 and high molecular weight cytokeratin (HMWCK)] is typical of classic acinar prostatic adenocarcinoma. We studied the expression and diagnostic utility of p63/HMWCK/AMACR immunohistochemical cocktail staining in ductal adenocarcinoma and cribriform Gleason pattern 4 acinar prostate cancer and compared it to noncribriform Gleason pattern 4 acinar prostate cancer. One to 4 representative formalin-fixed paraffin-embedded archival tissue blocks from 62 radical prostatectomy specimens harboring prostate cancer of ductal (n=51), cribriform Gleason pattern 4 acinar (n=27), and noncribriform Gleason pattern 4 acinar adenocarcinoma (n=48) were included in this study. Immunohistochemistry was performed using a triple stain of AMACR, p63, and HMWCK. Only staining that was moderate or strong was considered positive. The percentage of staining intensity and the presence of occasional basal cells positive with p63/HMWCK were recorded in each histologic type of prostatic adenocarcinoma. Seventy-seven percent of ductal prostatic adenocarcinoma, 67% of cribriform acinar prostatic carcinoma, and 81% of noncribriform acinar prostatic carcinoma showed positive staining for AMACR. There was no statistically significant difference between AMACR staining among the 3 histologic types, although there was a trend for noncribriform acinar prostatic carcinoma to have greater expression of AMACR than cribriform acinar prostatic carcinoma (P=0.07). Staining was often heterogeneous, varying in staining intensities within the same histologic type of carcinoma. Basal cells were detectable by p63 and HMWCK in a patchy fashion in 31.4% (16/51) of ductal and 29.6% (8/27) of cribriform acinar carcinomas compared with 2.1% (1/48) of noncribriform acinar carcinomas. In summary: (1) the majority of prostatic ductal and cribriform acinar carcinomas strongly expressed AMACR, however, subpopulations of these prostatic carcinoma were either completely negative or only weakly positive; (2) AMACR staining was often heterogeneous in intensity in the same histologic type of tumor, even within the same case; (3) patchy basal cell staining in noncribriform acinar prostatic carcinoma is rare. In contrast, remnants of basal cells identified by p63/HMWCK were seen in a patchy fashion in a significant minority of both ductal and cribriform acinar prostatic adenocarcinoma, which most likely represents intraductal spread of tumor.

My approach to intraductal lesions of the prostate gland

The morphologically heterogeneous (intra)ductal lesions of the prostate frequently present a diagnostic challenge, particularly when found within prostate needle biopsies. By current convention, all high-grade intra-acinar and intraductal neoplastic lesions of prostatic origin fall under the diagnostic umbrella term: prostatic intraepithelial neoplasm (PIN). Although a long-standing contentious issue, some lesions currently adhering to the diagnostic criteria of PIN may actually represent the intraductal spread of (generally high grade) invasive cancer. Illustrating this fact, the well-described ductal subtype of prostatic adenocarcinoma is frequently associated with conventional-type acinar adenocarcinoma, and has a tendency to propagate within adjacent intact prostatic ducts. Clearly, the misdiagnosis of lesions representing invasive disease as preinvasive has the potential for unfavourable clinical sequelae. As yet, however, many of these lesions have escaped the establishment of reliable morphologic criteria or immunohistochemical differentiation for diagnosis. By defining stringent architectural and cytonuclear features specific for each of these lesions, it may be feasible to separate potentially sinister lesions from the subset of traditional (preinvasive) PIN lesions with limited clinical urgency. This review discusses the (intra)ductal lesions of the prostate, along with their differential diagnoses. Given the current state of knowledge, a pragmatic approach to their effective reporting is outlined, taking into consideration the clinical implications, as well as current guidelines for treatment and follow-up.

The utility of Ki-67 expression in the differential diagnosis of prostatic intraepithelial neoplasia and ductal adenocarcinoma

Cribriform and/or papillary prostatic lesions observed on limited tissue, such as needle biopsy, can pose diagnostic dilemmas. One such area of difficulty is the distinction between papillary and/or cribriform prostatic high-grade prostatic intraepithelial neoplasia (HG-PIN) and ductal adenocarcinoma. Over 48 months, we identified 17 cases of ductal adenocarcinoma and 17 cases of HG-PIN from radical retropubic prostatectomy specimens. The HG-PIN lesions were in all cases associated with an acinar prostatic adenocarcinoma component. For each case, we evaluated the proliferative activity, assessed by Ki-67 immunohistochemistry. The majority (82%) of ductal adenocarcinomas were composed of mixed papillary and cribriform patterns, with the remaining demonstrating pure papillary or cribriform patterns. The HG-PIN lesions showed a papillary, cribriform, or mixed papillary/cribriform architecture. The proliferative activity, defined as Ki-67 labeling index, was statistically higher in ductal adenocarcinoma (mean 33%, range 21%-66%) as compared with HG-PIN (mean 6%, range 2%-15%), with no overlap in the Ki-67 indices (P = 0001). A combination of histological features and measurements of cellular proliferation may be helpful to distinguish HG-PIN from ductal adenocarcinoma in limited prostatic tissue samples.

Immunohistochemistry in diagnostic surgical pathology of the prostate

Immunohistochemistry (IHC) can play an important role in diagnostic surgical pathology of the prostate. Basal cell markers, such as the 34betaE12 antibody and antibodies directed against cytokeratin 5 and 6 or p63, are very useful for demonstration of basal cells as their presence argues against a diagnosis of invasive prostatic carcinoma (PC). However, several benign mimickers of PC, including atrophy, atypical adenomatous hyperplasia (AAH), nephrogenic adenoma, and mesonephric hyperplasia, can stain negatively with these markers, and thus, a negative basal cell marker immunostain alone does not exclude a diagnosis of benignancy. Although there are examples in the literature of high grade PC that stain focally with some of the basal cell markers, these cases are usually readily diagnosed based on H&E appearances and are unlikely to be confused with these benign mimickers. Alpha-methylacyl-coenzyme-A racemase (AMACR) is a sensitive marker of PC (except for a few uncommon variants: atrophic, foamy gland, and pseudohyperplastic variants), and its detection by immunohistochemical staining in atypical prostatic lesions can be very useful in confirming an impression of adenocarcinoma. AMACR expression can also be identified in high grade prostatic intraepithelial neoplasia (PIN), prostatic atrophy, AAH, and benign prostatic glands, and accordingly, a diagnosis of PC should not be based solely on a positive AMACR immunostain, especially when the luminal staining is weak and/or noncircumferential. The use of AMACR/basal cell antibody cocktails has been found to greatly facilitate the distinction between PC and its benign mimickers, especially when only limited tissue is available for staining. Prostate specific antigen (PSA) and prostate specific acid phosphatase (PSAP) are both quite sensitive and fairly specific markers of PC (there are a few nonprostatic tumors that can express one or both), and are both very helpful in establishing or confirming the diagnosis of PC when the differential diagnosis includes other tumors that can involve the prostate such as urinary bladder urothelial carcinoma. 34betaE12, p63, thrombomodulin, and uroplakin III are additional urothelial associated markers useful in this differential diagnosis. CDX2 and villin are useful markers to diagnostically separate colonic adenocarcinoma from PC. AMACR positivity and negative basal cell marker reactions are useful to confirm the presence of residual PC after hormonal or radiation therapy. Pan-cytokeratin, PSA, and PSAP can also highlight subtle infiltrates of PC with hormonal or radiation therapy effect. PSA and PSAP immunohistochemical stains are valuable in confirming metastatic carcinoma as being of prostatic origin and should always be utilized in the diagnostic evaluation of metastatic adenocarcinoma of unknown primary origin in males.

Unusual subtypes of prostate cancer

The vast majority of prostatic tumors developing in adult males are adenocarcinomas. For the most part, variations in histology have not received specific designations and, from a practical approach, have had any specific prognostic implications handled through application of the Gleason grading system. Nonetheless, some of the adenocarcinoma variants have specific clinical features and differential diagnoses. Furthermore, there has been some controversy regarding the appropriate application of the Gleason grading scheme in these tumors. In addition, there are carcinomas that are in fact not adenocarcinomas and that should be kept as distinct entities. In this paper, the histologic variants of adenocarcinoma are reviewed with emphasis on clinicopathologic features and the clinical relevance of these subtypes. Other carcinomas that occur in the prostate gland are also discussed again with a focus on the clinicopathologic characteristics.

Precancerous lesions and conditions of the prostate: from morphological and biological characterization to chemoprevention

Prostatic intraepithelial neoplasia (PIN) is composed of dysplastic cells with a luminal cell phenotype, expressing the androgen receptor as well as prostate-specific antigen. PIN is characterized by progressive abnormalities of phenotype that are intermediate between normal prostatic epithelium and cancer, indicating impairment of cell differentiation and regulatory control with advancing stages of carcinogenesis. High-grade PIN is considered the most likely precursor of prostatic carcinoma, according to virtually all available evidence. Androgen deprivation decreases the prevalence and extent of PIN and the degree of capillary vascularization (e.g., angiogenesis) in the surrounding stroma via suppression of vascular endothelial growth factor production. Prostatic carcinoma is also likely to arise from precursor lesions other than high-grade PIN such as low-grade PIN, atypical adenomatous hyperplasia, malignancy-associated foci, and atrophy.

Morphological identification of the patterns of prostatic intraepithelial neoplasia and their importance

High grade prostatic intraepithelial neoplasia (PIN) is the most likely precursor of prostatic carcinoma. PIN has a high predictive value as a marker for carcinoma, and its identification in biopsy specimens warrants repeat biopsy for concurrent or subsequent carcinoma. The only methods of detection are biopsy and transurethral resection; PIN does not greatly raise the concentration of serum prostate specific antigen (PSA) or its derivatives, does not induce a palpable mass, and cannot be detected by ultrasound. Androgen deprivation decreases the prevalence and extent of PIN, suggesting that this form of treatment might play a role in chemoprevention. Radiotherapy is also associated with a decreased incidence of PIN.

Does prostatic ductal adenocarcinoma exist?

Prostatic ductal (endometrioid) adenocarcinoma has been considered a distinct pathologic and clinical entity since it was first described more than 30 years ago. Its current status as a unique neoplasm is controversial, however, because it has considerable histologic overlap with typical acinar adenocarcinoma, particularly in small specimens such as needle biopsies. There are also conflicting views regarding its clinical behavior. We recently encountered a series of typical peripheral zone cancers of the prostate gland with prominent papillary or cribriform pattern that apparently did not involve the large periurethral prostatic ducts or verumontanum. To determine the incidence of these "ductal features" in nonductal carcinoma, we reviewed the findings in 338 consecutive totally embedded whole-mount prostatectomy specimens with typical clinical and pathologic features of acinar carcinoma. We defined carcinoma with significant "ductal features" as one that displayed papillary or cribriform pattern involving an arbitrarily defined aggregate focus at least 5 mm in diameter. Anti-keratin 34beta-E12 immunohistochemical staining for basal cells allowed exclusion of areas of papillary or cribriform pattern of high-grade prostatic intraepithelial neoplasia. We identified carcinoma with ductal features (papillary or cribriform growth) in 17 prostatectomy specimens (5% of cases) exclusively in the peripheral zone without involving the periurethral region. Papillary pattern was present in 11 of these cases (65%) and cribriform pattern in 10 (59%), including 4 cases (24%) with both patterns. Of 11 needle biopsy specimens available for examination from these 17 cases, 4 (36%) contained at least focal papillary or cribriform pattern of carcinoma. We conclude that adenocarcinoma arising in the peripheral zone of the prostate gland may display ductal carcinoma features (papillary or cribriform growth) classically associated with ductal adenocarcinoma. These findings, together with the recognized near-constant association of prostatic ductal adenocarcinoma and typical prostate cancer, suggest that ductal adenocarcinoma results from spread of typical prostatic acinar carcinoma into the large accommodating periurethral ducts and stroma, and that there are no unique histologic features other than site of growth. Identification of papillary or cribriform growth of cancer in prostate needle biopsies usually results from peripheral zone adenocarcinoma and not ductal adenocarcinoma.

Patterns of high-grade prostatic intraepithelial neoplasia associated with clinically aggressive prostate cancer

High-grade prostatic intraepithelial neoplasia (PIN) is the only widely accepted precursor lesion for prostatic adenocarcinoma (PCa). However, the spread of established PCa within prostatic ducts may be indistinguishable morphologically from high-grade PIN. By convention, all cytologically malignant cellular proliferations within prostatic ducts have been lumped into a PIN category, although there have been recent attempts by McNeal to develop reproducible criteria to separate high-grade PIN from the spread of established PCa within prostatic ducts--intraductal carcinoma (IDCa). Using McNeal's criteria for IDCa, we studied whole-mount sections from 252 patients with pT3NO PCa for the presence of IDCa and correlated the presence or absence of IDCa with Gleason score, total tumor volume, surgical margin status, seminal vesicle involvement, and disease progression. Patients with IDCa had higher Gleason score and total tumor volume and were more likely to show seminal vesicle involvement and disease progression than those patients without IDCa. In addition, IDCa was of independent prognostic significance. Total tumor volume and surgical margin status had no independent prognostic significance in this data set.