Interobserver and intraobserver reproducibility in digital and routine microscopic assessment of prostate needle biopsies

Advances in whole slide digital imaging in the past decade necessitate validation of these tools in each organ system in advance of clinical adoption. We assessed reproducibility in reporting prostate needle biopsy parameters among urologic pathologists using routine and digital microscopy in a consultation/second opinion-like setting. Four urologic pathologists evaluated a single core level from 50 diagnostically challenging needle biopsy specimens by routine microscopy and whole slide digital imaging. Interobserver and intraobserver agreement were calculated for primary and secondary Gleason grades, Gleason score, tumor quantitation (percentage and size in millimeters), and perineural invasion. Interobserver agreement for routine microscopy was excellent for primary Gleason grade (κ = 0.72) and good for all other parameters (κ ranging from 0.36 to 0.55). Whole slide digital imaging assessment yielded similar agreement for all parameters. Intraobserver agreement for primary Gleason grade and Gleason score was very good to excellent for all pathologists (all κ ≥ 0.65 and ≥ 0.73, respectively). Size of tumor in millimeters consistently displayed higher levels of agreement than percentage of tumor across media and pathologists. Digital assessment of routinely reported cancer parameters on prostatic needle biopsy for a given scanned core level is comparable to that of routine microscopy. These findings imply that histologic interpretation using dynamic whole slide images may accurately simulate routine microscopic evaluation in the consultation setting. Implementation of whole slide digital imaging in these scenarios may significantly reduce the workload of large referral centers in the near future and impact the manner in which pathologists seek second opinion consultation on challenging cases.     

Prostate needle biopsy examination by means of virtual microscopy

This study aimed at determining whether virtual microscopy improves the accuracy in the pathological examination of prostate needle biopsies regarding maximum tumor length, percentage of positive cores, and Gleason grading.We assessed a series of 816 prostate needle biopsy cores in 68 consecutive patients with prostate adenocarcinoma. Biopsy specimens were reviewed using conventional examination. Then, slides were converted to whole slide imaging (Olympus BX51). Tumor was measured, and Gleason score was assigned using the OlyVia software. Optically evaluated pathological features were compared with digital findings to determine whether one of these two methods for the assignment of a preoperative Gleason score is appropriate for predicting the definitive Gleason score of radical prostatectomy.When comparing optical and digital measurements, maximum tumor length in biopsy cores and percent prostate needle biopsy with cancer showed no significant difference. The mean variation in the measurement of tumor length was 2.65 mm per biopsy. Among 240 biopsy cores involved with cancer, the concordance rate for Gleason score assignment was 75.8% (κ = 0.49, good agreement). When considering the higher Gleason score assignment as the score for the entire case (ISUP 2005), the concordance rate was 69.1% (κ = 0.46, good agreement). When comparing the biopsy scores with the definitive score of radical prostatectomy, the concordance rate was significantly increased from 54.4% for conventional examination (κ = 0.23, marginal agreement) to 66.2% for virtual slide examination (κ = 0.42, good agreement).Virtual microscopy does not compromise, but might improve, the accuracy of grading in prostate needle biopsies. This requires further assessment.     

Basal cell hyperplasia: an unusual diagnostic dilemma on prostate needle biopsies

Basal cell hyperplasia (BCH) is a well-recognized entity on transurethral resection specimens, but it is an uncommon finding on prostatic needle biopsies, and the diagnostic difficulties with it have not been fully defined on this material. A 13-year (1991-2003) retrospective review of the consult files of one of the authors was performed. In all cases, the focus of BCH was referred for consultation to rule out adenocarcinoma. Thirty-three cases of prominent BCH were identified. The dominant pattern of BCH consisted of either glands (26/33) or solid nests (7/33). Other minor patterns included cribriform (5), pseudocribriform (4), cords (1), and adenoid basal (1). Twelve of 33 cases showed an infiltrative pattern. Other features of BCH included prominent nucleoli (14/33), abnormal secretions (17/33 with dense pink and/or blue mucin), mitoses (6/33), altered stroma with increased cellularity (6/33), calcifications (6/33), intraluminal crystalloids (3/33) and perineural invasion (1/33). By immunohistochemistry, 7 (100%) out of 7 were positive for p63 and 14 (88%) of 16 were positive for high molecular weight cytokeratin. No cases (0/6) were positive for alpha-methylacyl-coenzyme A racemase. Basal cell hyperplasia, as a mimicker of cancer, is an uncommon entity encountered on prostatic needle biopsies. Helpful features for its diagnosis include solid nests, pseudocribriform glands, multilayering of cells, calcifications, and cellular stroma. Immunohistochemistry can be useful for documenting the basal cell layer and demonstrating negative racemase staining.     

Current practice of Gleason grading of prostate carcinoma

The Gleason grading system remains one of the most powerful prognostic factors in prostate cancer and is the dominant method around the world in daily practice. It is based solely on the glandular architecture performed at low magnification. The Gleason grading system should be performed in needle core biopsies and radical prostatectomy specimens where it shows a reasonable degree of correlation between both specimens, and most importantly, it remains vital in the treatment decision-making process. This review summarizes the current status of Gleason grading in prostate cancer, incorporating recent proposals for the best contemporary practice of prostate cancer grading.     

Routine dual-color immunostaining with a 3-antibody cocktail improves the detection of small cancers in prostate needle biopsies

We performed dual-color immunostaining with a 3-antibody cocktail (α-methylacyl coenzyme-A racemase, CK34betaE12, and p63) on prostate biopsies from 200 patients. Current practice (hematoxylin and eosin staining followed by dual-color immunostaining on selected cases) was compared with a protocol in which routine dual-color immunostaining was provided in all cases. In the original pathology reports, adenocarcinoma was diagnosed in 87/200 (43%) patients. Small foci interpreted as putative cancers were detected with dual-color immunostaining in 14/113 patients who were originally diagnosed with a nonmalignant lesion. All of the suggested cancerous foci were independently reevaluated by 5 pathologists. A diagnosis of adenocarcinoma was assessed by consensus in 8 cases, and atypical small acinar proliferation was diagnosed in 1 case. Consensus was not reached in 5 cases. Six of the foci reclassified as cancer were of Gleason score 3 + 3 = 6, while 2 were graded as Gleason score 4 + 4 = 8. The feasibility of routine dual-color immunostaining was also tested by analyzing the time spent on microscopic assessment. Because small, atypical lesions expressing α-methylacyl coenzyme-A racemase (blue chromogen) were easy to detect using dual-color immunostaining, the microscopic analysis of dual-color immunostaining and hematoxylin-eosin staining was faster than that of hematoxylin-eosin staining alone that was later followed by dual-color immunostaining in selected cases (median 251 seconds versus 299 seconds, P < .0001). We concluded that routine dual-color immunostaining of all prostate biopsies would produce better diagnostic sensitivity with a smaller microscopy workload for the pathologist. However, minute foci interpreted as cancer with dual-color immunostaining need to be confirmed with hematoxylin-eosin staining, and minimal criteria for a definitive diagnosis of cancer are still lacking.     

Saturation biopsy improves preoperative Gleason scoring of prostate cancer

We evaluated the differences between conventional needle biopsy (CB) and saturation biopsy (SB) techniques with regard to the prediction of Gleason score, tumor stage, and insignificant prostate cancer.     

Stromogenic prostatic carcinoma pattern (carcinomas with reactive stromal grade 3) in needle biopsies predicts biochemical recurrence-free survival in patients after radical prostatectomy

We previously reported that reactive stromal grading in radical prostatectomies is a predictor of recurrence and that reactive stromal grading 0 and 3 are associated with lower biochemical recurrence-free survival rates than reactive stromal grading 1 and 2. We explored the prognostic significance of reactive stromal grading in preoperative needle biopsies. At Baylor College of Medicine, 224 cases of prostatic carcinoma were diagnosed by needle biopsy. Reactive stromal grading was evaluated on hematoxylin-eosin (H&E)-stained sections on the basis of previously described criteria: grade 0, with 0% to 5% reactive stroma; grade 1, 6% to 15%; grade 2, 16% to 50%; grade 3, 51% to 100%, or at least a 1:1 ratio between glands and stroma. Kaplan-Meier and Cox proportional hazard analyses were used. Reactive stromal grading distribution was as follows: reactive stromal grading 0, 1 case (0.5%); reactive stromal grading 1, 149 cases (66.5%); reactive stromal grading 2, 59 cases (26.3%); reactive stromal grading 3, 15 cases (6.7%). Reactive stromal grading in biopsies was correlated with adverse clinicopathologic parameters in the prostatectomy. Patients with reactive stromal grading 1 and 2 had better survival than those with 0 and 3 (P = .0034). Reactive stromal grading was an independent predictor of recurrence (hazard ratio = 1.953; P = .0174). Reactive stromal grading is independent of Gleason 4 + 3 and 3 + 4 in patients with a Gleason score of 7. Quantitation of reactive stroma and recognition of the stromogenic carcinoma in H&E-stained biopsies is useful to predict biochemical recurrence in prostate carcinoma patients independent of Gleason grade and prostate-specific antigen.     

Discrepancies between Gleason scores of needle biopsy and radical prostatectomy specimens

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

Reprint of: Stromogenic prostatic carcinoma pattern (carcinomas with reactive stromal grade 3) in needle biopsies predicts biochemical recurrence-free survival in patients after radical prostatectomy

We previously reported that reactive stromal grading in radical prostatectomies is a predictor of recurrence and that reactive stromal grading 0 and 3 are associated with lower biochemical recurrence-free survival rates than reactive stromal grading 1 and 2. We explored the prognostic significance of reactive stromal grading in preoperative needle biopsies. At Baylor College of Medicine, 224 cases of prostatic carcinoma were diagnosed by needle biopsy. Reactive stromal grading was evaluated on hematoxylin-eosin (H&E)-stained sections on the basis of previously described criteria: grade 0, with 0% to 5% reactive stroma; grade 1, 6% to 15%; grade 2, 16% to 50%; grade 3, 51% to 100%, or at least a 1:1 ratio between glands and stroma. Kaplan-Meier and Cox proportional hazard analyses were used. Reactive stromal grading distribution was as follows: reactive stromal grading 0, 1 case (0.5%); reactive stromal grading 1, 149 cases (66.5%); reactive stromal grading 2, 59 cases (26.3%); reactive stromal grading 3, 15 cases (6.7%). Reactive stromal grading in biopsies was correlated with adverse clinicopathologic parameters in the prostatectomy. Patients with reactive stromal grading 1 and 2 had better survival than those with 0 and 3 (P = .0034). Reactive stromal grading was an independent predictor of recurrence (hazard ratio = 1.953; P = .0174). Reactive stromal grading is independent of Gleason 4 + 3 and 3 + 4 in patients with a Gleason score of 7. Quantitation of reactive stroma and recognition of the stromogenic carcinoma in H&E-stained biopsies is useful to predict biochemical recurrence in prostate carcinoma patients independent of Gleason grade and prostate-specific antigen.     

The value of second-opinion pathology diagnoses on prostate biopsies from patients referred for management of prostate cancer

Gleason score (GS) (sum of primary plus secondary grades) is used to predict patients' clinical outcome and to customize treatment strategies for prostate cancer (PC). However, due in part to pathologist misreading, there is significant discrepancy of GS between needle-core biopsies (NCB) and radical prostatectomy specimens. We assessed the requirement for re-evaluating NCB diagnosed by outside pathologists in patients referred to our institution for management of PC. In 100 patients, we reviewed both their original "outside" and second-opinion ("in-house") diagnoses of the same NCB specimens, and compared them with the diagnoses of the whole-mount radical prostatectomy (WMRP) specimens (gold standard for analysis). We found that both outside and in-house biopsy GS vary significantly from the WMRP diagnoses, with GS undergrading substantially predominating above overgrading. Statistical analysis demonstrated that the main diagnostic discrepancy was in the differentiation between primary and secondary Gleason grades (mainly 3 and 4) and that outside NCB GS was significantly less accurate with respect to the WMRP specimens than the in-house NCB GS. In addition, in a different cohort of 65 NCB cases, we found that in 5 out of 11 patients, outside pathologists failed to report the presence of extraprostatic extension, an important feature for diagnosis of a higher pathology stage (pT3a). Since histopathological evaluation is a critical factor for appropriate treatment selection, we recommend that a re-evaluation by in-house urologic pathologists should be performed in all outside NCB specimens before patients are admitted for treatment in any given institution.     

Expression characteristics of prostate-derived Ets factor support a role in breast and prostate cancer progression

The purpose of this study was to understand the characteristics of prostate-derived Ets factor (PDEF) protein expression in breast and prostate cancer progression. A polyclonal antibody specific to PDEF was raised and reacted with tissue microarrays consisting of benign breast, in situ ductal, invasive ductal, and invasive lobular breast carcinomas. The antibody was also reacted with tissue microarrays, including benign prostate, prostate intraepithelial neoplasias (PINs), and prostate carcinomas. Increased expression of PDEF was identified in 18%, 50%, 46%, and 51% of benign breast tissues, intraductal, invasive ductal, and invasive lobular carcinomas, respectively. Importantly, in matched samples of benign breast vs tumor, 90% showed higher expression of PDEF in the tumor tissue. Moreover, in invasive breast carcinomas, increased PDEF expression tended to correlate with Her2/neu overexpression. Increased expression of PDEF was also found in 27%, 33%, and 40% of benign prostate tissues, PIN samples, and prostate adenocarcinomas, respectively. Again, in matching samples of cancer vs benign and cancer vs PIN, 68% and 70%, respectively, showed increased expression in the malignant tissue. Moreover, PDEF was found to be more highly expressed in tumors with intermediate or high Gleason score compared with low-grade tumors (P < .01). In addition, R1881 treatment induced PDEF expression in the LNCaP prostate tumor cell line, suggesting regulation of PDEF by androgens in vivo. Together, these results for the first time show frequent increased expression of PDEF protein in breast and prostate tumors and support a role for PDEF in breast and prostate cancer progression.     

Evaluation of whole slide image immunohistochemistry interpretation in challenging prostate needle biopsies

Whole slide images (WSIs), also known as virtual slides, can support electronic distribution of immunohistochemistry (IHC) stains to pathologists that rely on remote sites for these services. This may lead to improvement in turnaround times, reduction of courier costs, fewer errors in slide distribution, and automated image analyses. Although this approach is practiced de facto today in some large laboratories, there are no clinical validation studies on this approach. Our retrospective study evaluated the interpretation of IHC stains performed in difficult prostate biopsies using WSIs. The study included 30 foci with IHC stains identified by the original pathologist as both difficult and pivotal to the final diagnosis. WSIs were created from the glass slides using a scanning robot (T2, Aperio Technologies, Vista, CA). An evaluation form was designed to capture data in 2 phases: (1) interpretation of WSIs and (2) interpretation of glass slides. Data included stain interpretations, diagnoses, and other parameters such as time required to diagnose and image/slide quality. Data were also collected from an expert prostate pathologist, consensus meetings, and a poststudy focus group. WSI diagnostic validity (intraobserver pairwise kappa statistics) was "almost perfect" for 1 pathologist, "substantial" for 3 pathologists, and "moderate" for 1 pathologist. Diagnostic agreement between the final/consensus diagnoses of the group and those of the domain expert was "almost perfect" (kappa = 0.817). Except for one instance, WSI technology was not felt to be the cause of disagreements. These results are encouraging and compare favorably with other efforts to quantify diagnostic variability in surgical pathology. With thorough training, careful validation of specific applications, and regular postsignout review of glass IHC slides (eg, quality assurance review), WSI technology can be used for IHC stain interpretation.     

Trends in prostate needle biopsy diagnosis. A ten year experience of a medical center in Taiwan

Prostate cancer has seen a rapid rise in Taiwanese men. The current study was undertaken to evaluate trends of the disease diagnosed on prostate needle biopsy during a ten-year period at the Department of Pathology, Taipei Veterans General Hospital. The study included 8236 men who underwent a total of 9995 prostate needle biopsies at this institute from 1994 to 2003. Pathologic features pertinent to diagnosis of cancer were reviewed and compared for cases diagnosed before and after 1999. There were statistically significant increases of the overall cancer detection rate (from 17.6% to 19.9%), proportion of cases with a Gleason score ≤ 6 (from 16.6% to 40.9%) and focal adenocarcinoma (from 3.0% to 12.8%) in the latter 5 years. The incidence of high-grade prostatic intraepithelial neoplasia (HGPIN) increased from 0.1% to 1.5%. Patients with HGPIN had a significantly higher risk for subsequent cancer discovered on repeat biopsy than did those with a primary benign diagnosis (29.9% versus 13.7%). Despite a relatively lower incidence of cancer and HGPIN in Taiwanese men compared with that reported in Western studies, in recent years we have found an increase of relevant diagnoses, especially cancer of limited extent and lower grade, which may represent the progress in prostate cancer diagnosis.     

Optimization of prostate cancer diagnosis by increasing the number of core biopsies based on gland volume

In this prospective, non-randomized phase-I clinical trial, we comparatively studied the performance of six laterally-directed biopsies or the modified fan-shaped biopsies (MFSB), midline sextant biopsies (MB), and transition zone biopsies (TZB) and examine their prostate cancer (PCa) detection rates. A total of 114 patients received combinations of MFSB, MB, and TZB based on prostate gland volume: those ≤15cc received 8 biopsies; those >15cc but ≤ 50cc received 14 biopsies; and those >50cc received 20 biopsies. The mean prostate-specific antigen (PSA) level, Gleason score, and prostate volume were 8.0 ng/ml, 6.4, and 47 cc, respectively. PCa detection rate of the MB was 25% while the MFSB was 22%. The overall PCa detection rate was 33.3% with all biopsies. PCa and high-grade prostatic intraepithelial neoplasia (HG-PIN) detection rates decrease as the size of the prostate increases. PCa detection rates were 50.0% for volumes ≤19.9cc and volumes of >50cc had a detection rate of 25.8%. PSA levels of <3.0 had PCa detection rates of 15% which increased to 58% with PSA levels >9.0. In a multivariate analysis, only TZB was significant for PCa diagnosed by PSA (β=7.4, p<0.01). Our study showed that it is important to perform both the lateral MFSB and the MB to improve overall PCa detections rates. Thus, we recommend performing MB, MFSB, and TZB based on prostate volume, as follows: 8 biopsies for ≤15 cc; 14 for those >15 cc but ≤50 cc, and 14-20 for those >50 cc.     

Gleason grading of prostate cancer: a pragmatic approach

The Gleason grading system that was initiated by a surgeon, created by a pathologist and developed by a statistician predated serum PSA testing, systematic 18-gauge needle biopsy protocols and immunohistochemistry. It has undergone a series of modifications, initially by Veterans Administration Cooperative Urological Research Group and later by the International Society of Urological Pathologists following consensus meetings in 2005 and 2014. This review focusses on selected areas of practical difficulty such as borderline grades, cores with different Gleason scores, reporting of percentage pattern 4 and minor high-grade patterns, intraductal carcinoma and the new grading system for prostate cancer. We offer a pragmatic guide to grading prostate carcinoma and explain how precision of grading becomes less important if the pathologist uses judgment to determine the Gleason score most suitable for that patient, communicates this data effectively in the report and helps clinicians interpret the information correctly.