Histologic grading of breast carcinoma: a multi-institution study of interobserver variation using virtual microscopy

Breast carcinoma grading is an important prognostic feature recently incorporated into the AJCC Cancer Staging Manual. There is increased interest in applying virtual microscopy (VM) using digital whole slide imaging (WSI) more broadly. Little is known regarding concordance in grading using VM and how such variability might affect AJCC prognostic staging (PS). We evaluated interobserver variability amongst a multi-institutional group of breast pathologists using digital WSI and how discrepancies in grading would affect PS. A digitally scanned slide from 143 invasive carcinomas was independently reviewed by 6 pathologists and assigned grades based on established criteria for tubule formation (TF), nuclear pleomorphism (NP), and mitotic count (MC). Statistical analysis was performed. Interobserver agreement for grade was moderate (κ = 0.497). Agreement was fair (κ = 0.375), moderate (κ = 0.491), and good (κ = 0.705) for grades 2, 3, and 1, respectively. Observer pair concordance ranged from fair to good (κ = 0.354-0.684) Perfect agreement was observed in 43 cases (30%). Interobserver agreement for the individual components was best for TF (κ = 0.503) and worst for MC (κ = 0.281). Seventeen of 86 (19.8%) discrepant cases would have resulted in changes in PS and discrepancies most frequently resulted in a PS change from IA to IB (n = 9). For two of these nine cases, Oncotype DX results would have led to a PS of 1A regardless of grade. Using VM, a multi-institutional cohort of pathologists showed moderate concordance for breast cancer grading, similar to studies using light microscopy. Agreement was the best at the extremes of grade and for evaluation of TF. Whether the higher variability noted for MC is a consequence of VM grading warrants further investigation. Discordance in grading infrequently leads to clinically meaningful changes in the prognostic stage.

Breast cancer histologic grading using digital microscopy: concordance and outcome association

Aims

Virtual microscopy utilising digital whole slide imaging (WSI) is increasingly used in breast pathology. Histologic grade is one of the strongest prognostic factors in breast cancer (BC). This study aims at investigating the agreement between BC grading using traditional light microscopy (LM) and digital WSI with consideration of reproducibility and impact on outcome prediction.

Methods

A large (n=1675) well-characterised cohort of BC originally graded by LM was re-graded using WSI. Two separate virtual-based grading sessions (V1 and V2) were performed with a 3-month washout period. Outcome was assessed using BC-specific and distant metastasis-free survival.

Results

The concordance between LM grading and WSI was strong (LM/WSI Cramer’s V: V1=0.576, and V2=0.579). The agreement regarding grade components was as follows: tubule formation=0.538, pleomorphism=0.422 and mitosis=0.514. Greatest discordance was observed between adjacent grades, whereas high/low grade discordance was uncommon (1.5%). The intraobserver agreement for the two WSI sessions was substantial for grade (V1/V2 Cramer’s V=0.676; kappa=0.648) and grade components (Cramer’s V T=0.628, p=0.573 and M=0.580). Grading using both platforms showed strong association with outcome (all p values <0.001). Although mitotic scores assessed using both platforms were strongly associated with outcome, WSI tends to underestimate mitotic counts.

Conclusions

Virtual microscopy is a reliable and reproducible method for assessing BC histologic grade. Regardless of the observer or assessment platform, histologic grade is a significant predictor of outcome. Continuing advances in imaging technology could potentially provide improved performance of WSI BC grading and in particular mitotic count assessment.

A Randomized Study Comparing Digital Imaging to Traditional Glass Slide Microscopy for Breast Biopsy and Cancer Diagnosis

Background:

Digital whole slide imaging may be useful for obtaining second opinions and is used in many countries. However, the U.S. Food and Drug Administration requires verification studies.

Methods:

Pathologists were randomized to interpret one of four sets of breast biopsy cases during two phases, separated by ≥9 months, using glass slides or digital format (sixty cases per set, one slide per case, n = 240 cases). Accuracy was assessed by comparing interpretations to a consensus reference standard. Intraobserver reproducibility was assessed by comparing the agreement of interpretations on the same cases between two phases. Estimated probabilities of confirmation by a reference panel (i.e., predictive values) were obtained by incorporating data on the population prevalence of diagnoses.

Results:

Sixty-five percent of responding pathologists were eligible, and 252 consented to randomization; 208 completed Phase I (115 glass, 93 digital); and 172 completed Phase II (86 glass, 86 digital). Accuracy was slightly higher using glass compared to digital format and varied by category: invasive carcinoma, 96% versus 93% (P = 0.04); ductal carcinoma in situ (DCIS), 84% versus 79% (P < 0.01); atypia, 48% versus 43% (P = 0.08); and benign without atypia, 87% versus 82% (P < 0.01). There was a small decrease in intraobserver agreement when the format changed compared to when glass slides were used in both phases (P = 0.08). Predictive values for confirmation by a reference panel using glass versus digital were: invasive carcinoma, 98% and 97% (not significant [NS]); DCIS, 70% and 57% (P = 0.007); atypia, 38% and 28% (P = 0.002); and benign without atypia, 97% and 96% (NS).

Conclusions:

In this large randomized study, digital format interpretations were similar to glass slide interpretations of benign and invasive cancer cases. However, cases in the middle of the spectrum, where more inherent variability exists, may be more problematic in digital format. Future studies evaluating the effect these findings exert on clinical practice and patient outcomes are required.

Educational Value of Digital Whole Slides Accompanying Published Online Pathology Journal Articles: A Multi-Institutional Study

CONTEXT

-Despite great interest in using whole slide imaging (WSI) in pathology practice and education, few pathology journals have published WSI pertinent to articles within their pages or as supplemental materials.

OBJECTIVE

-To evaluate whether there is measurable added educational value of including WSI in publications.

DESIGN

-Thirty-seven participants, 16 (43.3%), 15 (40.5%), and 6 (16.2%) junior pathology residents (postgraduate year 1-2), senior pathology residents (postgraduate year 3-4), and board-certified pathologists, respectively, read a sequence of 10 journal articles on a wide range of pathology topics. A randomized subgroup also reviewed the WSI published with the articles. Both groups completed a survey tool assessing recall of text-based content and of image-based material pertinent to the diseases but not present in the fixed published images.

RESULTS

-The group examining WSI had higher performance scores in 72% of image-based questions (36 of 50 questions) as compared with the non-WSI group. As an internal study control, the WSI group had higher performance scores in only 40% of text-based questions (6 of 15 questions). The WSI group had significantly better performance than the non-WSI group for image-based questions compared with text-based questions (P < .05, Fisher exact test).

CONCLUSION

-Our study provides supporting evidence that WSI offers enhanced value to the learner beyond the text and fixed images selected by the author. We strongly encourage more journals to incorporate WSI into their publications.

Validation of an electronic program for pathologist training in the interpretation of a complex companion diagnostic immunohistochemical assay

Companion diagnostics assay interpretation can select patients with the greatest targeted therapy benefits. We present the results from a prospective study demonstrating that pathologists can effectively learn immunohistochemical assay-interpretation skills from digital image-based electronic training (e-training). In this study, e-training was used to train board-certified pathologists to evaluate non-small cell lung carcinoma for eligibility for treatment with onartuzumab, a MET-inhibiting agent. The training program mimicked the live training that was previously validated in clinical trials for onartuzumab. A digital interface was developed for pathologists to review high-resolution, static images of stained slides. Sixty-four pathologists practicing in the United States enrolled while blinded to the type of training. After training, both groups completed a mandatory final test using glass slides. The results indicated both training modalities to be effective. Overall, 80.6% of e-trainees and 72.7% of live trainees achieved passing scores (at least 85%) on the final test. All study participants reported that their training experience was "good" and that they had received sufficient information to determine the adequacy of case slide staining to score each case. This study established that an e-training program conducted under highly controlled conditions can provide pathologists with the skills necessary to interpret a complex assay and that these skills can be equivalent to those achieved with face-to-face training using conventional microscopy. Programs of this type are scalable for global distribution and offer pathologists the potential for readily accessible and robust training in new companion diagnostic assays linked to novel, targeted, adjuvant therapies for cancer patients.

Clinical Neuropathology Views - 2/2016: Digital networking in European neuropathology: An initiative to facilitate truly interactive consultations

Digital technology is progressively changing our vision of the practice of neuropathology. There are a number of facts that support the introduction of digital neuropathology. With the development of whole-slide imaging (WSI) systems the difficulties involved in implementing a neuropathology network have been solved. A relevant difficulty has been image standardization, but an open digital image communication protocol defined by the Digital Imaging and Communications in Medicine (DICOM) standard is already a reality. The neuropathology network should be established in Europe because it is the expected geographic context for relationships among European neuropathologists. There are several limitations in the implementation of a digital neuropathology consultancy network such as financial support, operational costs, legal issues, and technical assistance of clients. All of these items have been considered and should be solved before implementing the proposal. Finally, the authors conclude that a European digital neuropathology network should be created for patients’ benefit.

Digitized whole slides for breast pathology interpretation: current practices and perceptions

Digital whole slide imaging (WSI) is an emerging technology for pathology interpretation; however, little is known about pathologists' practice patterns or perceptions regarding WSI. A national sample (N = 252) of pathologists from New Hampshire, Vermont, Washington, Oregon, Arizona, Alaska, Maine, and Minnesota were surveyed in this cross-sectional study (2011-2013). The survey included questions on pathologists' experience, WSI practice patterns, and perceptions using a six-point Likert scale. Agreement was summarized with descriptive statistics to characterize pathologists' use and perceptions of WSI. The majority of participating pathologists were males (63%) between 40 and 59 years of age (70%) and not affiliated with an academic medical center (72%). Experience with WSI was reported by 49%. Types of use reported included CME/board exams/teaching (28%), tumor board/clinical conference (22%), archival purposes (6%), consultative diagnosis (4%), research (4%), and other uses (12%). Most respondents (79%) agreed that accurate diagnoses can be made with this technology, and that WSI is useful for obtaining a second opinion (88%). However, 78% of pathologists agreed that digital slides are too slow for routine clinical interpretation. Fifty-nine percent agreed that the benefits of WSI outweigh concerns. The respondents were equally split as to whether they would like to adopt WSI (51%) or not (49%). About half of pathologists reported experience with the WSI technology, largely for CME, licensure/board exams, and teaching. Positive perceptions regarding WSI slightly outweigh negative perceptions. Understanding practice patterns with WSI as dissemination advances may facilitate concordance of perceptions with adoption of the technology.

Overview of contemporary guidelines in digital pathology: what is available in 2015 and what still needs to be addressed?

As technological advancements continue to transform the practice of pathology, new adopters of these technologies will look to guidelines on how best to incorporate them with an eye to preserving and enhancing patient safety and diagnostic quality. Telepathology, using a variety of digital pathology modalities, has tremendous potential to achieve that goal. Pathology departments are increasingly looking to implement different digital pathology platforms, whole slide imaging (WSI) systems in particular, for a broad range of applications in patient care. WSI allows for the acquisition, management and review of completely digitised slides as would be done with a light microscope. WSI also facilitates image analysis that cannot be carried out by a pathologist using traditional microscopy. Over the last few years, the Digital Pathology Association, The Royal College of Pathologists, College of American Pathologists, Canadian Association of Pathologists, the American Telemedicine Association and the Society of Toxicologic Pathology have published guidelines for validating and implementing digital pathology systems. This review summarises, compares and contrasts these published guidelines and discusses pertinent issues that need to be addressed as the guidelines are revised in the future.

The College of American Pathologists guidelines for whole slide imaging validation are feasible for pediatric pathology: a pediatric pathology practice experience

Whole slide imaging (WSI) is rapidly transforming educational and diagnostic pathology services. Recently, the College of American Pathologists Pathology and Laboratory Quality Center (CAP-PLQC) published recommended guidelines for validating diagnostic WSI. We prospectively evaluated the guidelines to determine their utility in validating pediatric surgical pathology and cytopathology specimens. Our validation included varied pediatric specimen types, including complex or less common diagnoses, in accordance with the guidelines. We completed WSI review of 60 surgical pathology cases and attempted WSI review of 21 cytopathology cases. For surgical pathology cases, WSI diagnoses were highly concordant with glass slide diagnoses; a discordant diagnosis was observed in 1 of 60 cases (98.3% concordance). We found that nucleated red blood cells and eosinophilic granular bodies represented specific challenges to WSI review of pediatric specimens. Cytology specimens were more frequently discordant or failed for technical reasons, with overall concordance of 66.7%. Review of pediatric cytopathology specimens will likely require image capture in multiple focal planes. This study is the first to specifically evaluate WSI review for pediatric specimens and demonstrates that specimens representing the spectrum of pediatric surgical pathology practice can be reviewed using WSI. Our application of the proposed CAP-PLQC guidelines to pediatric surgical pathology specimens is, to our knowledge, the first prospective implementation of the CAP-PLQC guidelines.

The future of laboratory medicine - a 2014 perspective

Predicting the future is a difficult task. Not surprisingly, there are many examples and assumptions that have proved to be wrong. This review surveys the many predictions, beginning in 1887, about the future of laboratory medicine and its sub-specialties such as clinical chemistry and molecular pathology. It provides a commentary on the accuracy of the predictions and offers opinions on emerging technologies, economic factors and social developments that may play a role in shaping the future of laboratory medicine.

Carnegie Mellon University bioimaging day 2014: Challenges and opportunities in digital pathology

Recent advances in digital imaging is impacting the practice of pathology. One of the key enabling technologies that is leading the way towards this transformation is the use of whole slide imaging (WSI) which allows glass slides to be converted into large image files that can be shared, stored, and analyzed rapidly. Many applications around this novel technology have evolved in the last decade including education, research and clinical applications. This publication highlights a collection of abstracts, each corresponding to a talk given at Carnegie Mellon University's (CMU) Bioimaging Day 2014 co-sponsored by the Biomedical Engineering and Lane Center for Computational Biology Departments at CMU. Topics related specifically to digital pathology are presented in this collection of abstracts. These include topics related to digital workflow implementation, imaging and artifacts, storage demands, and automated image analysis algorithms.

Digital pathology services in acute surgical situations

The future for out-of-hours pathology services

Improved access to histopathology using a digital system could increase the organ donor pool and improve allocation

Improvements in digital slide scanners have reached a stage that digital whole slide images (WSIs) can be used for diagnostic purposes. A digital system for histopathology, analogous to the systems used in radiology, would allow the establishment of networks of subspecialist histopathologists to provide a regional, national or even international rota to support out of hours histopathology for emergency frozen sections, urgent paraffin sections and to generally improve efficiencies with the provision of histopathology services. Such a system would promote appropriate organ utilization by allowing rapid characterization of unexpected lesions in the donor to determine whether donation should occur and further characterization of the organ, such as the degree of fibrosis in the kidney or steatosis in the liver, to determine whether the organ should be used. If introduced across Europe, this would promote safe and effective exchange of organs and support a cost efficient use of pathologist expertise. This review article outlines current issues with the provision of an urgent out of hours histopathology service and focuses on how such a service has the potential to increase organ donors, improve allocation, sharing and the use of available donor organs.