Perineural invasion, mucinous fibroplasia, and glomerulations: diagnostic features of limited cancer on prostate needle biopsy

Prostate Cancer: Update on Grading and Reporting

The Gleason scoring system and Grade Group systems facilitate accurate grading and reporting of prostate cancer, which are essential tasks for surgical pathologists. Gleason Pattern 4 is critical to recognize because it signifies a risk for more aggressive behavior than Gleason Pattern 3 carcinoma. Prostatic adenocarcinoma with radiation or androgen therapy effect, with aberrant P63 expression, or with Paneth cell-like differentiation represent pitfalls in prostate cancer grading because although they display architecture associated with aggressive behavior in usual prostatic adenocarcinoma, they do not behave aggressively and using conventional Gleason scoring in these tumors would significantly overstate their biologic potential.

Prostate cancer grading: a decade after the 2005 modified system

This review article will cover the evolution of grading of prostate cancer from the original Gleason system in the 1960-1970s to a more patient-centric grading system proposed in 2013 from a group at Johns Hopkins Hospital, validated in 2014 by a large multi-institutional study, and subsequently accepted by the World Health Organization (WHO), College of American Pathology (CAP), and the AJCC TNM system. Covered topics include: (1) historical background; (2) 2005 and 2014 International Society of Urological Pathology Grading Conferences; (3) Description of Gleason patterns; (4) new approaches to display Gleason grades; (5) grading variants and variations of acinar adenocarcinoma; (6) reporting rules for Gleason grading reporting secondary patterns of higher grade when present to a limited extent; (7) reporting secondary patterns of lower grade when present to a limited extent; (8) reporting percentage pattern 4; (9) general applications of the Gleason grading system; (10) needle biopsy with different cores showing different grades; (11) radical prostatectomy specimens with separate tumor nodules; and (12) a new grading system for prostate cancer.

Prostate cancer: diagnostic criteria and role of immunohistochemistry

The diagnosis of prostate cancer is based on microscopic criteria. Presently, prostate needle biopsy interpretation can be a challenge for the pathologist due to the increased number of specimens with limited amount of suspicious glands and minimal atypia. It is critical for the pathologist to have an organized methodical approach when considering the morphological features enabling a definitive diagnosis of prostate cancer. Although several diagnostic criteria and supportive features have been advocated, only few findings are absolutely specific and diagnostic of prostate cancer. The diagnosis of prostate cancer relies on a combination of architectural and cytological features that are reviewed in detail herein. Infiltrative growth pattern, prominent nucleoli and lack of basal cells are the most useful diagnostic criteria. Perineural invasion, glomerulation and mucinous fibroplasia are pathognomonic features of prostate cancer, although uncommon on small prostate cancer foci. The role of immunohistochemistry in establishing a diagnosis of limited prostate is addressed.

Histopathology of Prostate Cancer

This review focuses on histopathological aspects of carcinoma of the prostate. A tissue diagnosis of adenocarcinoma is often essential for establishing a diagnosis of prostate cancer, and the foundation for a tissue diagnosis is currently light microscopic examination of hematoxylin and eosin (H&E)-stained tissue sections. Markers detected by immunohistochemistry on tissue sections can support a diagnosis of adenocarcinoma that is primary in the prostate gland or metastatic. Histological variants of carcinoma of the prostate are important for diagnostic recognition of cancer or as clinicopathologic entities that have prognostic and/or therapeutic significance. Histological grading of adenocarcinoma of the prostate, including use of the 2014 International Society of Urological Pathology (ISUP) modified Gleason grades and the new grade groups, is one of the most powerful prognostic indicators for clinically localized prostate cancer, and is one of the most critical factors in determination of management of these patients.

Artefact as the Pathologist’s Friend: Peritumoral Retraction in In Situ and Infiltrating Duct Carcinoma of the Breast

Peritumoral retraction artefact appears in tissue sections as an empty space partially or completely encircling a nest of tumor cells, usually in conformity with the rounded or angular outline of that particular nest. The present study was designed to test this finding in a large series of cases and to quantify the appearance of peritumoral retraction artefact in, in situ and infiltrating duct carcinoma of the breast. We examined 199 cases of infiltrating duct carcinoma (IDC) and 188 cases of ductal carcinoma in situ (DCIS). Of the total of 387 cases, 111 were core needle biopsies, whereas the others were larger resections. In each specimen, retraction was evaluated on hematoxylin and eosin-stained slides as negative, 1+ (1% to 25% of tumor showing retraction), 2+ (26% to 50%), 3+ (51% to 75%), or 4+ (76% to 100%). Overall, peritumoral retraction was noted in 168 of 199 cases (84.4%) of IDC, versus 30 of 188 cases (16%) of DCIS ( P < 0.0001). Peritumoral retraction scored as 2+ or greater (26% to 50%) was seen in only 1 of 188 DCIS specimens, compared with 77 of 199 IDC. Thus, peritumoral retraction artefact appears to be a significant finding seen during the evaluation of hematoxylin and eosin specimens for the diagnosis of carcinoma. We discuss the possibility that this phenomenon might represent true prelymphatic space involvement rather than a fixation artefact.

Grading of prostatic adenocarcinoma: current state and prognostic implications

Background

Despite significant changes in the clinical and histologic diagnosis of prostate cancer, the Gleason grading system remains one of the most powerful prognostic predictors in prostate cancer. The correct diagnosis and grading of prostate cancer is crucial for a patient’s prognosis and therapeutic options. However, this system has undergone significant revisions and continues to have deficiencies that can potentially impact patient care.

Main Body

We describe the current state of grading prostate cancer, focusing on the current guidelines for the Gleason grading system and recent changes from the 2014 International Society of Urological Pathology Consensus Conference on Gleason Grading of Prostatic Carcinoma. We also explore the limitations of the current Gleason grading system and present a validated alternative to the Gleason score. The new grading system initially described in 2013 in a study from Johns Hopkins Hospital and then validated in a multi-institutional study, includes five distinct Grade Groups based on the modified Gleason score groups. Grade Group 1 = Gleason score ≤6, Grade Group 2 = Gleason score 3 + 4 = 7, Grade Group 3 = Gleason score 4 + 3 = 7, Grade Group 4 = Gleason score 8, Grade Group 5 = Gleason scores 9 and 10.

Conclusion

As this new grading system is simpler and more accurately reflects prostate cancer biology, it is recommended by the World Health Organization (WHO) to be used in conjunction with Gleason grading.

A retrospective analysis of 111 canine prostatic samples: histopathological findings and classification

The purpose of this retrospective study is to evaluate the frequency and further characterize the pathological features of common and uncommon histological lesions in 111 canine prostatic samples. Benign prostatic hyperplasia, suppurative and non-suppurative prostatitis, and prostate cancer were observed individually or in combination in 45, 11, 68 and 50 samples, respectively. Six growth patterns of prostatic carcinoma were differentiated: papillary, cribriform, solid, small acinar/ductal, signet ring, mucinous. In a few cases, perineurial invasion and collagenous micronodules were observed. Lesions considered preneoplastic in men, such as high-grade prostatic intraepithelial neoplasia (HGPIN) and prostatic inflammatory atrophy (PIA), were observed in 27 and 21 histological samples, respectively. This study represents a detailed characterization of the different histological subtypes of canine prostate cancer. The awareness of the unusual patterns might be critical in avoiding diagnostic misinterpretation. The high prevalence of PIA and HGPIN underlines the reasonable chance of their detection in routine biopsy specimens.

Precursor lesions of mucinous carcinoma of the breast: analysis of 130 cases

Mucinous mammary carcinoma (MC) is a tumor type with relatively favorable prognosis. Unlike the circumstances surrounding conventional invasive duct carcinoma, data are limited regarding precursor lesions for MC. This study characterizes patterns of mucinous ductal carcinoma in situ (DCIS) as a precursor lesion for MC. All slides from 130 cases of MC encountered between 2000 and 2011 at Henry Ford Hospital, Detroit, MI were reviewed to subclassify MC, identify DCIS, and explore transition patterns from DCIS to MC. Calponin, p63, chromogranin, synaptophysin, CD56, and MIB-1 immunostaining analyses were performed in 65 cases. Among 106 cases of pure (71 type A, 35 type B) and 24 cases of mixed MC, DCIS appeared in 88 (68%) specimens, with all but 4 showing luminal mucin accumulation. Dominant patterns of mucinous DCIS were cribriform/solid (66), cribriform and papillary (7), papillary (5), micropapillary (3), and flat (3). Fifty-seven (68%) cases of mucinous DCIS demonstrated transitions from DCIS to MC. Luminal mucinous distention, focal flattening and attenuation of the epithelium, and disruption of the duct wall resulting in a mucocele-like extravasation of malignant epithelia with escaping mucin was a transition pattern seen with all architectures of DCIS and in all types of MC. This was the only pattern of transition to type A MC. The epithelial outpouching, formation of a cleft with accumulation of mucin around the epithelium, and transition into mucin pools with floating tumor cell clusters was the second transition pattern that went from cribriform/solid DCIS to type B and mixed MC. DCIS preceding aggressive phenotypes of MC (type B and mixed) more often had a cribriform/solid architecture, higher nuclear grade, and higher Ki-67-labeling index (all P<0.05). In summary, mucinous DCIS is a precursor to MC with distinctive features that link patterns of DCIS with aggressive MC phenotypes. The 2 observed transitions between mucinous DCIS and MC suggest that pathogenesis of different types of MC is different correlating with less or more aggressive behavior of the latter.

Mucin-producing tumors and tumor-like lesions involving the prostate: a comprehensive review

Mucin-producing tumors of the prostate include both primary and secondary tumors with mucinous differentiation or features involving the prostate gland. These tumors are relatively rare and have variable prognostic and therapeutic implications. Primary mucinous (colloid) adenocarcinoma of the prostate is defined as prostatic adenocarcinoma with mucinous differentiation involving 25% or more of the entire tumor. Another primary tumor of the prostate that may have mucinous features is primary mucin-producing urothelial-type adenocarcinoma of the prostate (mucinous prostatic urethral adenocarcinoma). Primary mucin-producing urothelial-type adenocarcinoma of the prostate is a distinct entity that typically arises from the prostatic urethra possibly from urethritis glandularis or glandular metaplasia with malignant transformation, and it is analogous to adenocarcinoma with mucinous differentiation arising from the urinary bladder. Signet ring cell tumors of the prostate, though rare, may also have mucinous features. Secondary tumors with mucinous differentiation that may involve the prostate include adenocarcinomas of the urinary bladder and colorectum. Pathologists should also be aware of mucin-producing tumor-like lesions involving the prostate, including mucinous metaplasia, and benign Cowper glands that may mimic malignancy. Herein we present an updated and comprehensive review of the clinicopathologic, immunohistochemical, molecular, and prognostic features of mucinous tumors and tumor-like lesions involving the prostate gland, with emphasis on mucinous prostatic adenocarcinoma and its mimickers, including potential diagnostic pitfalls.

Variants and unusual patterns of prostate cancer: clinicopathologic and differential diagnostic considerations

Beyond the typical acinar morphology observed in the majority of prostatic adenocarcinomas, a spectrum of morphologic variants and prostate cancer subtypes exists. These unusual entities may be classified as: (1) cancer morphologies arising by divergent differentiation of prostatic ductal, acinar, or basal cells and associated with unique clinical features and/or therapeutic approaches, and (2) histologies occurring in the context of usual prostatic adenocarcinoma that may result in diagnostic misinterpretation or difficulties in Gleason grade assignment, especially in limited samples. This article details a number of variants, with emphasis on diagnostic criteria, differential diagnoses, and clinical significance.

Periacinar retraction clefting in nonneoplastic and neoplastic prostatic glands: artifact or molecular involvement

A space between neoplastic acini and prostatic stroma is not rare and studies have interpreted this as an artifact, considering the absence of endothelial cells indicating vascular invasion. Thus, the aims of this work were to characterize and correlate the occurrence and extent of retraction clefting with the reactivities of α and β dystroglycan (αDG, βDG), laminin, matrix metalloproteinase 2 (MMP-2), p63, insulin-like growth factor 1(IGF-1), vimentin, and fibroblast growth factor 2 (FGF-2). The study was based on nonneoplastic and neoplastic prostatic tissues obtained from necropsies and retropubic radical prostatectomies. The results showed that periacinar retraction clefting was significantly more frequent in prostatic carcinoma samples than in normal prostatic acini. Most of the neoplastic acini (72.0%) showed retraction clefting of more than 50% of circumference, which were significantly more frequent in Gleason score 7 and 6. Decreased collagen and reticular and elastic fibers were verified in the stroma around neoplastic acini. Weak and discontinuous αDG, βDG, and laminin immunoreactivities and intensified MMP-2, vimentin, IGF-1 and FGF-2 immunoreactivities were verified in the neoplastic acini; p63 immunoreactivity was negative in all carcinomas. Thus, these findings showed that the lack of epithelial basal cells, DGs, and laminin and increased MMP-2, IGF-1, and FGF-7 could be considered important pathways in periacinar retraction occurrence. This study demonstrated the origin of and the biological mechanisms responsible for periacinar retraction clefting in prostatic carcinoma.

Morphological parameters associated with perineural invasion (PNI) in carcinoma of the cervix uteri

The study determines morphological features that are associated with perineural invasion (PNI) in patients with cervical carcinoma (CX). Histological slides from 194 patients from surgically treated squamous cell carcinoma were re-examined for PNI and correlated to morphological factors of tumor growth. Material from 68 patients (35.1%) represented PNI. PNI was significantly correlated with advanced tumor stage (P < .001). Patients with deep cervical stromal invasion (>66%) showed more PNI than those with more superficial invasion (41% vs 16.9%; P = .001). Tumors with spray-like PI showed significantly more PNI (48.4%) when compared with finger-like PI (26.7%) and those with pushing borders (18.8%; P = .007). Strong peritumoral desmoplastic stromal reaction and absence of peritumoral inflammation were associated with a higher frequency of PNI (P < .001). PNI is associated with advanced tumor stage, deep cervical stromal invasion (>66%), high grade of tumor cell dissociation (ie, spray-like pattern of invasion), strong peritumoral desmoplastic stromal reaction, and reduced peritumoral inflammation.

TMPRSS2-ERG gene fusion is associated with low Gleason scores and not with high-grade morphological features

TMPRSS2-ERG gene rearrangement is seen in about half of clinically localized prostate cancers, yet controversy exists with regard to its prognostic implications. Similarly, the relationship of TMPRSS2-ERG fusion to Gleason score and morphology remains uncertain. We assigned Gleason scores and recorded morphological features for 521 clinically localized prostate cancers sampled in triplicate and arrayed in eight tissue microarray blocks. Fluorescence in situ hybridization was performed to delineate TMPRSS2-ERG aberrations. Using maximum Gleason score, based on three core evaluation, and overall Gleason score, based on prostatectomy sections, Fisher's exact test was performed for tumors with TMPRSS2-ERG translocation/deletion, copy number increase (≥ 3) of the TMPRSS2-ERG region without translocation/deletion, and copy number increase and concomitant translocation/deletion. In all, 217 (42%) translocation/deletion and 30 (5.9%) copy number increase-alone cases were detected. Among 217 translocation/deletion cases, 32 had translocation/deletion with copy number increase. In all, 237, 200, and 75 cancers had maximum core-specific Gleason score of 6, 7, and 8-10, respectively. Tumors with translocation/deletion tended toward lower Gleason scores than those without (P=0.002) with similar results for overall Gleason score (P=0.02); copy number increase cases tended toward higher Gleason scores than those without (P<0.001). Gleason score of 8-10 tumors demonstrated lower odds of translocation/deletion (odds ratio (OR) 0.38; 95% CI 0.21-0.68) and higher odds of copy number increase alone (OR 7.33; 95% CI 2.65-20.31) or copy number increase+translocation/deletion (OR 3.03; 95% CI 1.12-8.15) relative to Gleason score of <7 tumors. No significant difference in TMPRSS2-ERG incidence was observed between patients with and without cribriform glands, glomerulations, signet-ring cells, or intraductal cancer (P=0.821, 0.095, 0.132, 0.375). TMPRSS2-ERG gene fusion is associated with lower core-specific and overall Gleason scores and not with high-grade morphologies. Conversely, TMPRSS2-ERG copy number increase, with or without rearrangement, is associated with higher Gleason score. These findings indicate that translocation/deletion of TMPRSS2-ERG is not associated with histological features of aggressive prostate cancer.

Perineural invasion: identification, significance, and a standardized definition

BACKGROUND

Mohs surgeons have expanded the range of cancers treated using the Mohs technique. Mohs surgeons today are expected to diagnose perineural invasion (PNI) when as little as one nerve is involved.

OBJECTIVE

To address the issue of identification and significance of perineural invasion from the perspective of the Mohs surgeon. The experience of other medical specialties dealing with the same issue are reviewed and applied.

METHODS AND MATERIALS

This article is based on a review of the entire medical literature regarding PNI.

RESULTS

PNI is a significant complication of cancers, regardless of the organ of origin. The most common complication of PNI is recurrence of the cancer. Leptomeningeal carcinomatosis occurs in neglected or aggressive cancers. The process is indolent and contiguous, lending itself well to treatment with Mohs surgery. There are diagnostic mimics of PNI. Variation of reported incidences and cure rates suggest that diagnostic criteria for PNI may not be consistent from study to study.

CONCLUSION

We propose the following definition for the minimum histopathologic criteria required to make a diagnosis of PNI: "In the presence of a malignancy, PNI may be diagnosed according to the observation of cytologically malignant cells in the perineural space of nerves. In equivocal cases, the observation of total or near-total circumferential involvement is supportive, as is the presence of perineural tracking in tangential sections and intraneural involvement."

Gleason grading of prostatic adenocarcinoma with glomeruloid features on needle biopsy

Glomerulations in prostatic adenocarcinoma are characterized by dilated glands containing intraluminal cribriform structures with a single point of attachment, resembling a renal glomerulus. On prostate biopsy, glomerulations are exclusively associated with carcinoma and not associated with benign mimickers. However, the Gleason grading of carcinoma with glomerulations on needle biopsy remains controversial. We prospectively collected 45 prostate needle biopsies containing carcinoma with glomeruloid features from our consult files for a 9-month period and examined the association between glomerulations and the presence of concurrent high-grade carcinoma. Glomerulations were overwhelmingly associated with high-grade cancer on the same core, composed of either Gleason pattern 4 (n = 36, 80% of cases) or Gleason pattern 5 (n = 2, 4% of cases). Only a minority of glomerulations were surrounded exclusively by pattern 3 cancer (n = 7, 16% of cases) on the same core. Most of the cases with surrounding pattern 4 cancer were scored as 3 + 4 = 7 (n = 24, 66%), whereas a smaller fraction were scored as 4 + 3 = 7 (n = 9, 26%), and only a minority were 4 + 4 = 8 (n = 3, 9%). In most cases, glomeruloid change was present on the same core as the highest Gleason score carcinoma of the case. None of the pattern 3 cases and only a minority of the pattern 4 cancers had higher Gleason score carcinoma on additional cores (n = 5, 14%). Glomeruloid structures are a rare but diagnostic feature of prostatic carcinoma on needle biopsy. Our data indicate that glomerulations are overwhelmingly associated with concurrent Gleason pattern 4 or higher-grade carcinoma. In several cases, transition could be seen among small glomerulations, large glomeruloid structures, and cribriform pattern 4 cancer. These data suggest that glomerulations represent an early stage of cribriform pattern 4 cancer and, until follow-up data are available, are best graded as Gleason pattern 4.

Variants and Unusual Patterns of Prostate Cancer

Beyond the typical acinar morphology observed in most prostatic adenocarcinoma, a spectrum of morphologic variants and prostate cancer subtypes exists. These unusual entities may be further classified into (1) cancer morphologies arising by divergent differentiation of prostatic ductal, acinar, or basal cells and associated with unique clinical features or therapeutic approaches, and (2) histologies occurring in the context of usual prostatic adenocarcinoma that may result in diagnostic misinterpretation or difficulties in Gleason grade assignment, especially in limited samples. This article details several variants, with emphasis on diagnostic criteria, differential diagnoses, and clinical significance.

Morphological features of TMPRSS2-ERG gene fusion prostate cancer

The TMPRSS2-ETS fusion prostate cancers comprise 50-70% of the prostate-specific antigen (PSA)-screened hospital-based prostate cancers examined to date, making it perhaps the most common genetic rearrangement in human cancer. The most common variant involves androgen-regulated TMPRSS2 and ERG, both located on chromosome 21. Emerging data from our group and others suggests that TMPRSS2-ERG fusion prostate cancer is associated with higher tumour stage and prostate cancer-specific death. The goal of this study was to determine if this common somatic alteration is associated with a morphological phenotype. We assessed 253 prostate cancer cases for TMPRSS2-ERG fusion status using an ERG break-apart FISH assay. Blinded to gene fusion status, two reviewers assessed each tumour for presence or absence of eight morphological features. Statistical analysis was performed to look for significant associations between morphological features and TMPRSS2-ERG fusion status. Five morphological features were associated with TMPRSS2-ERG fusion prostate cancer: blue-tinged mucin, cribriform growth pattern, macronucleoli, intraductal tumour spread, and signet-ring cell features, all with p-values < 0.05. Only 24% (n=30/125) of tumours without any of these features displayed the TMPRSS2-ERG fusion. By comparison, 55% (n=38/69) of cases with one feature (RR=3.88), 86% (n=38/44) of cases with two features (RR=20.06), and 93% (n=14/15) of cases with three or more features (RR=44.33) were fusion positive (p<0.001). To our knowledge, this is the first study that demonstrates a significant link between a molecular alteration in prostate cancer and distinct phenotypic features. The strength of these findings is similar to microsatellite unstable colon cancer and breast cancer involving BRCA1 and BRCA2 mutations. The biological effect of TMPRSS2-ERG overexpression may drive pathways that favour these common morphological features that pathologists observe daily. These features may also be helpful in diagnosing TMPRSS2-ERG fusion prostate cancer, which may have both prognostic and therapeutic implications.

Atypical small acinar proliferation: biopsy artefact or distinct pathological entity?

OBJECTIVE

To determine if atypical small acinar proliferation (ASAP) represents minimally sampled prostate cancer not fully evaluated on a biopsy or a distinct pathological entity, by examining prostates removed at radical cystectomy, as a finding of ASAP of the prostate on needle-core biopsy is closely associated with the detection of cancer on subsequent biopsy.

PATIENTS AND METHODS

In all, 65 consecutive cystoprostatectomy specimens taken from June 1990 to March 2004 had prostatic material reviewed by one genitourinary pathologist (S.E.M.). The presence of high-grade prostatic intraepithelial neoplasia (HGPIN), ASAP, and adenocarcinoma was recorded. Foci of ASAP found in the absence of cancer were assessed with additional sectioning, high-molecular weight keratin (CK903), and alpha-methylacyl coenzyme A racemase (AMACR) immunohistochemistry.

RESULTS

In all, 24 of 65 specimens (37%) had adenocarcinoma. Of the 41 without cancer, 18 (44%) had neither HGPIN nor ASAP, 14 (34%) had HGPIN alone, three (7%) had ASAP alone (four foci), and six had both HGPIN and ASAP (15%). Two foci of ASAP were not present on any further sectioning. The remaining eight foci all lacked CK903 stain, indicating disruption of the basal cell layer. Of these eight, only five were present for the AMACR stain, all of which were positive. Two of these five developed into a lesion considered cancer on further sectioning.

CONCLUSION

ASAP identified in incidental prostates represented marginally sampled cancer in at least two of 10 foci assessed. The remainder could not be resolved as benign on further evaluation, and remained suspicious for malignancy.

Diagnosis of adenocarcinoma in prostate needle biopsy tissue

Prostate cancer is a major public health problem throughout the developed world. For patients with clinically localised prostate cancer, the diagnosis is typically established by histopathological examination of prostate needle biopsy samples. Major and minor criteria are used to establish the diagnosis, based on the microscopic appearance of slides stained using haematoxylin and eosin. Major criteria include an infiltrative glandular growth pattern, an absence of basal cells and nuclear atypia in the form of nucleomegaly and nucleolomegaly. In difficult cases, basal cell absence may be confirmed by immunohistochemical stains for high-molecular-weight cytokeratins (marked with antibody 34betaE12) or p63, which are basal cell markers. Minor criteria include intraluminal wispy blue mucin, pink amorphous secretions, mitotic figures, intraluminal crystalloids, adjacent high-grade prostatic intraepithelial neoplasia, amphophilic cytoplasm and nuclear hyperchromasia. Another useful diagnostic marker detectable by immunohistochemistry is alpha-methylacyl coenzyme A racemase (AMACR), an enzyme selectively expressed in neoplastic glandular epithelium. Cocktails of antibodies directed against basal cell markers and AMACR are particularly useful in evaluating small foci of atypical glands, and in substantiating a diagnosis of a minimal adenocarcinoma. Reporting of adenocarcinoma in needle biopsy specimens should always include the Gleason grade and measures of tumour extent in the needle core tissue. Measures of tumour extent are (1) number of cores positive for cancer in the number of cores examined, (2) percentage of needle core tissue affected by carcinoma and (3) linear millimetres of carcinoma present.

Morphological markers of secretory activity in prostatic adenocarcinoma

Background/Aim. The vast majority of prostatic tumors developing in adult males are adenocarcinomas (ACP). Histological diagnosis of prostate cancer relies on the infiltrative growth pattern, presence of macronucleoli, and absence of basal cell layer. In the last few years a special attention has been focused on investigation of cancerous glands lumen content. The aim of the study was to determine the presence of intraluminal (crystaloids, blue-tanged mucinous secretions and distension of glands) and extracellular markers of pathological secretions in ACP, as well as the type of intraluminal and extracellular mucinous secretions. Methods. Micromorphological and hystochemical (PAS, HIDAB pH 2.5) analysis was done in 96 patients to detemine differentiation by Gleason and markers of secretory activity. Results. In ACP neoplastic gland`s distension (53.12%), crystalloids (30.2%), basophilic secretions (26.04%) and presence of extracellular mucins (8.3%) were found. All morphological signs were detected in carcinoma of Gleason grade 1-4A. There was significant presence of crystalloids ((G1+G2)/G4 p < 0.05; G3/G4A p < 0.05), basophilic secretions (G3/G2 p < 0.05; G3/G4A p < 0.05) and extracellular mucins (G3/G4A p < 0.001). The association of these morphological features with neutral and acidic mucins secretion was statisticaly significant (p < 0.0001). Conclusion. This study showed that intraluminal and extracellular markers of secretory activity in ACP were significantly more often associated by mixed type of mucin secretion with predominace of sialomucins. .

Current practice of diagnosis and reporting of prostate cancer on needle biopsy among genitourinary pathologists

As there is a lack of hard data in the literature about many of the issues relating to diagnosing and reporting prostate cancer, we sought to survey current practices. A questionnaire was sent to 93 genitourinary pathologists with a response rate of 69%. Almost all respondents (95%) used formalin as fixative for needle biopsies. Unstained intervening sections were retained by 47%. Three levels of needle biopsies were used routinely by 63%. For verification of a diagnosis of cancer, high-molecular-weight cytokeratin was still the most commonly used immunohistochemical marker (91%), followed by p63 (58%) and alpha-methylacyl-CoA-racemase (50%). Features considered pathognomonic for cancer were glomeruloid bodies (58%), collagenous micronodules (64%), circumferential perineural invasion (84%), and growth in fat (36%). With none of these present, 39% required a minimum of 2 to 10 glands (median, 3) to diagnose cancer, whereas the others had no lower limit. A Gleason score was always given to even minute cancer foci by 86% and typically a Gleason score 6 was assigned (77%). Perineural invasion was mentioned by 86%. The extent of cancer on needle biopsies was quantified by all respondents with number of involved cores (80%) being the most commonly used measure. Linear extent was estimated by almost all, either as a percentage (80%) or millimeters of cancer length (41%) or both (22%). Measuring cancer from end to end or subtracting intervening benign tissue were almost equally common. For those general pathologists who would like to be in the mainstream of most urological pathologists, our survey data provide a guideline on how to diagnose and report prostate cancer.

Number and location of nucleoli and presence of apoptotic bodies in diagnostically challenging cases of prostate adenocarcinoma on needle biopsy

There is limited published data regarding the significance of the number or position of nucleoli and the presence of apoptotic bodies in diagnostically challenging cases of adenocarcinoma of the prostate on needle biopsy material. One hundred consecutive prostate cancers on needle biopsy were sent because of diagnostic difficulty to an expert in urological pathology, and the remaining normal benign prostatic glands on the same core were evaluated for the number and location of nucleoli and for the presence of mitotic figures and apoptotic bodies. The Gleason scores of the cases were 6 (86%), 7 (9%), and 8 to 10 (5%). For comparison, the same parameters were evaluated in mimickers of cancer on needle biopsy from other cases, including partial atrophy (n = 135), fully developed atrophy (n = 89), adenosis (n = 50), prostate glands with acute inflammation (n = 50), and high-grade prostatic intraepithelial neoplasia (n = 100). Findings were recorded under high dry magnification (x40) using hematoxylin and eosin-stained sections. Although the number and position of nucleoli did not discriminate between cancer and benign mimickers, mitotic figures and apoptotic bodies were more commonly seen in cancer. Apoptotic bodies in particular were seen fairly frequently (34%) in prostatic adenocarcinoma (also seen in 13% of high-grade prostatic intraepithelial neoplasia), yet rarely in benign mimickers on needle biopsy. Our findings indicate that the presence of apoptotic bodies should be added to the list of histological features that are helpful in the diagnosis of challenging cases of prostate cancer on needle biopsy.

Usefulness of epithelial membrane antigen (EMA) to discriminate between perineural invasion and perineural indentation in prostatic carcinoma

AIMS

Perineural invasion (PNI) is one of the few unequivocal criteria to diagnose adenocarcinoma of the prostate. Distinguishing PNI from perineural indentation (PNIn), however, is sometimes difficult. The aim of this study was to discriminate between PNI and PNIn using EMA immunohistochemistry.

METHODS AND RESULTS

We selected representative sections from 87 prostatectomies with prostatic adenocarcinoma. Normal peripheral nerves were continuously encircled with perineurium, which was immunoreactive for EMA. We identified 1319 PNI by carcinomas, 368 PNIn by carcinomas, and 303 PNIn by benign glands. We categorized the EMA immunoreactivity patterns into three classes: samples that displayed discontinuity or complete loss of the perineurium (Type A), samples where there were carcinomas or benign glands in the perineural space or peripheral nerves (Type B) and samples that showed no changes in the perineurium (Type C). For PNI we observed Type A, Type B, and Type C patterns in 55.3%, 24.8% and 19.9% of carcinomas, respectively. The incidence of each of those patterns in PNIn by carcinomas was 32.1%, 14.9% and 53.0%, respectively. Cases of PNIn by benign glands showed Type A or Type C patterns. They did not, however, exhibit Type B patterns.

CONCLUSION

EMA immunostaining will aid the diagnosis of prostatic adenocarcinoma.

Perineural Involvement by Benign Prostatic Glands on Needle Biopsy

Uncommonly, benign prostatic glands can be seen in the perineural space, known as "benign perineural involvement." This phenomenon has not been specifically studied on needle biopsies; 27 needle biopsy cases with perineural involvement were evaluated; 22 (81.4%) were received in consultation, while 5 (18.5%) were in-house cases. In 15 of 22 (68.2%) consult cases, a question was raised by the submitting pathologist regarding the focus. The following patterns of perineural involvement were observed: indentation 14 (51.8%) cases, by up to 3 glands; tracking 8 (29.6%) cases, by up to 6 glands; wrapping 7 (25.9%) from one half to three fourths around the nerve, by up to 3 glands, 1 case showed 95% wrapping; intraneural 4 (14.8%) cases by up to 3 glands; adjacent 2 (7.4%) cases by up to 2 glands. Partial atrophy in the involved glands was seen in 10 (38.4%) cases and complete atrophy in 6 (23%). Of 8 cases with the lesion still present on slides for immunohistochemistry, high molecular weight cytokeratin (HMWCK) and p63 were positive in 6 (75%) and negative in the 2 (25%) cases with partial atrophy. A total of 6 (27%) cases had more than one pattern of perineural involvement. On hematoxylin and eosin sections, basal cells were not identified in 12 (46%) cases, including 2 negative and 1 positive cases stained for HMWCK. Patterns most closely mimicking cancer included intraneural and incomplete perineural encirclement. Perineural invasion by benign atrophic glands cause diagnostic difficulty, especially with negative HMWCK. Careful attention to hematoxylin and eosin morphology and comparison of perineural involvement to adjacent and distant benign glands are necessary.

Perineural invasion in prostate cancer biopsies is not associated with higher rates of positive surgical margins

PURPOSE

High rates of extracapsular tumor extension have been reported with biopsy perineural invasion (PNI), leading some to advocate routine resection of the ipsilateral neurovascular bundle (NVB) with radical retropubic prostatectomy (RRP) to assure negative surgical margins. The contemporary rates of extracapsular tumor extension (ECE) and margin status associated with biopsy PNI were investigated.

MATERIALS AND METHODS

The prostate needle biopsies, RRP specimens, and operative reports of 452 consecutive patients undergoing RRP by a single surgeon were reviewed to determine the presence of PNI invasion, presence of ECE, margin status, and preservation of NVB. Patients were excluded from the analysis if they underwent preoperative hormonal ablation or if their original biopsy was not reviewed by the pathologists at our institution. Both univariate and multivariate analyses were performed to determine the effect of PNI on extracapsular extension, the likelihood of performing a bilateral nerve-sparing technique, and the result of a positive surgical margin.

RESULTS

In the 402 evaluable cases, based on multivariate models PNI showed only a marginal association with positive surgical margin (+SM) (P = 0.10) and bilateral nerve-sparing (B-NS) (P = 0.07), but was significantly associated with organ confinement (P = 0.03). The odds ratio (OR) of PNI for +SM, although not statistically significant, was 0.36. Although showing a higher level of statistical significance, PNI for OC had an odds ratio of 0.50. Similarly, the odds ratio was 0.54 for B-NS.

CONCLUSIONS

Although biopsy PNI alone was associated with a higher probability of ECE, it is not predictive of bilateral nerve-sparing technique or a positive surgical margin in an individual patient.

Diagnosis and reporting of limited adenocarcinoma of the prostate on needle biopsy

The diagnosis of limited adenocarcinoma of the prostate is one of the more difficult challenges in surgical pathology. This paper highlights the methodological approach to diagnosing limited cancer, based on a constellation of features more commonly present in adenocarcinoma than benign glands. In assessing small foci of atypical glands on needle biopsy, one looks for differences between the benign glands and the atypical glands in terms of nuclear features, cytoplasmic features, and intraluminal contents. Only a few features, such as glomerulations, mucinous fibroplasia (collagenous micronodules), and perineural invasion are diagnostic in and of themselves for prostate cancer. Immunohistochemistry may be a useful adjunct in the diagnosis of limited adenocarcinoma of the prostate, although as with any immunohistochemical studies, there are problems with both sensitivity and specificity. Basal cell markers, such as high molecular weight cytokeratin and more recently, p63, highlight basal cells found in benign glands, yet are absent in adenocarcinoma of the prostate. However, not all benign glands label uniformly with basal cell markers. Certain mimickers of adenocarcinoma of the prostate are even less frequently labeled uniformly with these stains. Consequently, negative staining in a small focus of atypical glands for basal cell markers is not diagnostic of adenocarcinoma of the prostate. More recently, a marker has been identified that relatively selectively labels adenocarcinoma of the prostate. AMACR will label the cytoplasm of approximately 80% of limited adenocarcinoma of the prostate cases on needle biopsy. In positive cases, not all of the glands will be positive and those that are positive are often not intensely positive. Certain variants of adenocarcinoma of the prostate that are a little more difficult to recognize, such as foamy glands adenocarcinoma, pseudohyperplastic adenocarcinoma, and atrophic adenocarcinoma, are labeled with AMACR in only approximately 60-70% of cases. In addition to problems with sensitivity, AMACR is not entirely specific for adenocarcinoma, and will label almost all cases of high-grade prostatic intraepithelial neoplasia, some foci of adenosis, and even some entirely benign glands. Finally, this paper will briefly cover the significance of atypical or suspicious prostate needle biopsies, and how to report the key diagnostic and prognostic information on needle biopsy.

Periacinar retraction clefting in the prostatic needle core biopsies: an important diagnostic criterion or a simple artifact?

The diagnosis of prostatic adenocarcinoma in needle core biopsy is based on major and supportive criteria. One of the supportive criteria is the presence of retraction clefting around neoplastic glands. We analyzed a series of 137 prostatic cancer cases diagnosed by needle core biopsy to determine the frequency, extent and criteria for periacinar retraction clefting. Clefting was analyzed on ten neoplastic and ten normal glands in three different high power fields. One-third or more glands with clefts affecting more than 50% of circumference were significantly more common in tumors (51.8%) than in benign glands (8%) (P<0.0001). A stricter criterion that designated as positive the cases with at least 50% of neoplastic glands (15 of 30) with clefts that affected more than 50% of circumference revealed clefts in only 15.3% of the malignant cases but none in benign cases (0%) (P<0.0001). Regardless of their extension, 15 or more glands with clefts were also more prominent in malignant cases (86.9%) than in benign cases (20.4%) (P<0.0001). We conclude that periacinar retraction clefting represents a reliable criterion for diagnosis of the prostatic adenocarcinoma, especially in cases with clefts affecting more than 50% of circumference in at least 50% of suspicious glands.

Pathological and molecular aspects of prostate cancer

This review focuses on new findings and controversial issues in the the pathology and molecular biology of adenocarcinoma of the prostate. Since management of high-grade prostatic intraepithelial neoplasia on needle biopsy--the most common precursor lesion to prostate cancer--is the crucial issue with this lesion, we discuss the risk of cancer subsequent to this histological diagnosis and the issue of whether such neoplasia should be regarded as carcinoma-in-situ. We also look at prostate cancer itself, starting with its diagnosis, reporting on needle biopsy, and reviewing how the most frequently used grading system, the Gleason grading system, affects treatment. The molecular basis of prostate cancer includes inheritable and somatic genetic changes (tumour suppressor genes, loss of heterozygosity, gene targets and regions of chromosomal gain, CpG island promoter methylation, invasion and metastasis suppressor genes, telomere shortening, and genetic instability). Changed gene expression (eg, proliferation-related genes, changes in the androgen receptor, apoptosis and stress-response genes) have potential as biomarkers and therapeutic targets in prostate cancer.

Pathogenesis and significance of collagenous micronodules of the prostate

Collagenous micronodules, also known as mucinous fibroplasia, are microscopic structures characterized by the presence of small eosinophilic nodules in areas immediately adjacent to prostatic glandular epithelium. The pathogenesis of collagenous micronodules is unknown, although their relation with mucin has been suggested. The objective of our study was to analyze the structural characteristics of collagenous micronodules by using histochemistry, immunohistochemistry, and electron microscopy to elucidate the pathogenesis of this lesion. We analyzed 15 cases of prostate adenocarcinoma (12 prostatectomy specimens and 3 biopsy specimens) with collagenous micronodules. The collagenous micronodules were closely associated with well-formed malignant glands, where tumor cells exhibited basophilic to amphophilic cytoplasm. Occasionally, intraluminal collagen fragments were observed within malignant but not benign glands. Collagenous micronodules were not associated with mucin, confirmed by negative stainings of mucicarmin or alcian blue in all the collagenous micronodules analyzed in this study. Therefore, the term "mucinous fibroplasia" may not be accurate. Collagenous micronodules stained weakly positive for periodic acid-Schiff. Trichrome stain highlighted the presence of collagenous micronodules as distinct blue structures. Collagen IV and laminin immunostaining performed in 12 cases outlined the micronodules with minimal staining in the center. These findings indicated that collagenous micronodules consisted of predominantly collagen fragments admixed with basement membrane material. Ultrastructurally, they were composed of fragmented banded collagen fibrils surrounded by the basement membrane material. Collagenous micronodules are formed by subepithelial accumulations of fragmented collagen fibers, possibly related to the digestion by collagenase produced by prostatic adenocarcinoma cells.

Morphologic criteria for the diagnosis of prostatic adenocarcinoma in needle biopsy specimens. A study of 250 consecutive cases in a routine surgical pathology practice

CONTEXT

The diagnosis of prostate adenocarcinoma in needle core biopsy specimens is based on multiple diagnostic criteria and supportive features, most of which have been defined mainly from observations in transurethral resection and prostatectomy specimens. There is little information on the frequency with which diagnostic and supportive features of prostate cancer occur within benign glands. The few reports dealing with diagnostic criteria of cancer in needle biopsies have been largely confined to analysis of selected cases that posed particular diagnostic difficulty.

OBJECTIVE

To analyze the frequency with which numerous diagnostic or supportive features of prostate cancer occur in an unselected, consecutively performed series of 18-gauge prostate needle biopsy specimens.

DESIGN

Two hundred fifty consecutive 18-gauge prostate needle biopsy specimens (150 malignant and 100 benign) were evaluated, using hematoxylin-eosin-stained histologic sections.

RESULTS

The frequency of the histologic features in malignant and benign glands was as follows: prominent nucleoli (94% and 25% of malignant and benign specimens, respectively), marginated nucleoli (88% and 7%), multiple nucleoli (64% and 0%), blue-tinged mucinous secretions (52% and 0%), intraluminal crystalloids (40.6% and 1%), intraluminal amorphous eosinophilic material (86.7% and 2%), collagenous micronodules (2% and 0%), glomerulations (15.3% and 0%), perineural invasion (22% and 0%), retraction clefting (38.6% and 7%), and invasion of fat (0.7% and 0%).

CONCLUSIONS

Since not all diagnostic or supportive features of cancer are evident in any single case of cancer, particularly in needle biopsy specimens in which sampling is limited, awareness of these data would be helpful in the assessment of small foci of atypical glands being considered for cancer.

Atypical ductal hyperplasia and ductal carcinoma in situ of the breast associated with perineural invasion

Perineural invasion is a histologic feature usually diagnostic of invasion in malignancies. In the breast, however, it has been associated with benign lesions such as sclerosing adenosis (SA), complex sclerosing lesion/radial scar (CSL/RS), and ductal carcinoma in situ (DCIS). This article describes perineural invasion associated with atypical ductal hyperplasia (ADH), florid hyperplasia without atypia (FH), and DCIS. All cases with a diagnosis of perineural invasion were selected from a series of 10,000 breast consult cases. Invasive mammary carcinomas were excluded. Fourteen cases of perineural invasion were found and associated with the following diagnoses: ADH (5), DCIS (3), FH (5), and ductal adenoma (1). Nine cases developed in CSL/RS, 4 cases in SA, and 1 case in a previous biopsy site of ductal adenoma; lesions were all less than 3 mm. The glands involving nerves showed cytologic and architectural features of the adjacent ADH, DCIS, and FH. Immunostaining for protein gene product (PGP) 9.5 marked nerves, and smooth muscle actin antibody highlighted the myoepithelial cells around glands. Perineural invasion seen in association with DCIS and ADH, in a background of CSL/RS and SA, may pose difficulty in diagnosis, especially in small biopsy specimens. It should be assessed with care to avoid misinterpretation as invasive mammary carcinoma.

Minimal adenocarcinoma in prostate needle biopsy tissue

One of the major diagnostic challenges in prostate needle biopsy interpretation is definitive establishment of a malignant diagnosis based on a minimal or limited amount of carcinoma in needle biopsy tissue. Major and minor diagnostic criteria should be used for interpretation of small foci of carcinoma. The constellation of findings and a combination of the major and minor diagnostic criteria permit a definitive diagnosis of focal adenocarcinoma. The differential diagnosis of minimal prostatic adenocarcinoma in needle biopsy tissue is broad and includes many benign lesions. The benign entities most likelty to be misdiagnosed as minimal prostatic adenocarcinoma are atypical adenomatous hyperplasia (adenosis) and atrophy. High-grade prostatic intraepithelial neoplasia and a descriptive diagnosis of focal glandular atypia or atypical small acinar proliferation also should be considered before diagnosing minimal adenocarcinoma. The most valuable adjunctive study for the diagnosis of minimal adenocarcinoma is immunohistochemistry using antibody 34 beta E12, reactive against basal cell-specific high-molecular-weight cytokeratins. Most cases can be diagnosed based on H&E-stained sections without this immunostain. Most minimal carcinomas in prostate needle biopsy tissue are of intermediate histologic grade, and most are indicative of pathologically significant carcinoma in the whole prostate gland.