Amendments in surgical pathology reports: An 8-year institutional experience.

Surgical pathology reports may undergo revisions broadly categorized as addenda (supplementary information) or amendments (changes to finalized reports). Amendments indicate potential flaws in the diagnostic process and serve as important indicators of vulnerabilities in the histopathology workflow. This study analyzed the frequency and distribution of amendments in surgical pathology reports over 8 years to identify patterns highlighting opportunities for improvement. Surgical biopsies, excisions, and resections were included; cytology and molecular tests were excluded. Amended reports were categorized using previously used taxonomy documented in literature. Defects were classified as misinterpretations, misidentifications, defective specimens, or defective reports. Of 101,355 reports, 155 (0.15 %) were signed out with amendments. The amendment rate was approximately 1-2 cases per 1000 reports annually. Misinterpretations accounted for the majority (52 %) of amended reports, with undercalls (62 %) and overcalls (27 %) being predominant subtypes. Tumor staging was amended in 57 (37 %) cases, with 30 being upstaged and 11 downstaged clinically. The highest number of misinterpretation defects occurred in head and neck (36 %) and breast (21 %) specimens. Misinterpretation defects were present in 53 % of malignant cases versus 42 % of benign cases. In 18 cases, there were significant changes in pathological diagnosis (14 major and 4 minor). A standard taxonomy categorizing report defects is crucial for measuring and improving quality control. Accurate pathology reporting impacts patient care and guides workflow improvements. This taxonomy enables us to track variations and deficiencies in our pathology reporting processes in a reproducible way across the department.

Towards a More Standardized Approach to Pathologic Reporting of Pancreatoduodenectomy Specimens for Pancreatic Ductal Adenocarcinoma: Cross-continental and Cross-specialty Survey From the Pancreatobiliary Pathology Society Grossing Working Group.

In recent literature and international meetings held, it has become clear that there are significant differences regarding the definition of what constitutes as margins and how best to document the pathologic findings in pancreatic ductal adenocarcinoma. To capture the current practice, Pancreatobiliary Pathology Society (PBPS) Grossing Working Group conducted an international multispecialty survey encompassing 25 statements, regarding pathologic examination and reporting of pancreatic ductal adenocarcinoma, particularly in pancreatoduodenectomy specimens. The survey results highlighted several discordances; however, consensus/high concordance was reached for the following: (1) the pancreatic neck margin should be entirely submitted en face, and if tumor on the slide, then it is considered equivalent to R1; (2) uncinate margin should be submitted entirely and perpendicularly sectioned, and tumor distance from the uncinate margin should be reported; (3) all other surfaces (including vascular groove, posterior surface, and anterior surface) should be examined and documented; (4) carcinoma involving separately submitted celiac axis specimen should be staged as pT4. Although no consensus was achieved regarding what constitutes R1 versus R0, most participants agreed that ink on tumor or at and within 1 mm to the tumor is equivalent to R1 only in areas designated as a margin, not surface. In conclusion, this survey raises the awareness of the discordances and serves as a starting point towards further standardization of the pancreatoduodenectomy grossing and reporting protocols.

Life Cycle Greenhouse Gas Emissions of Gastrointestinal Biopsies in a Surgical Pathology Laboratory.

OBJECTIVES: Given adverse health effects of climate change and contributions of the US health care sector to greenhouse gas (GHG) emissions, environmentally sustainable delivery of care is needed. We applied life cycle assessment to quantify GHGs associated with processing a gastrointestinal biopsy in order to identify emissions hotspots and guide mitigation strategies. METHODS: The biopsy process at a large academic pathology laboratory was grouped into steps. Each supply and reagent was catalogued and postuse treatment noted. Energy consumption was estimated for capital equipment. Two common scenarios were considered: 1 case with 1 specimen jar (scenario 1) and 1 case with 3 specimen jars (scenario 2). RESULTS: Scenario 1 generated 0.29 kg of carbon dioxide equivalents (kg CO2e), whereas scenario 2 resulted in 0.79 kg CO2e-equivalent to 0.7 and 2.0 miles driven, respectively. The largest proportion of GHGs (36%) in either scenario came from the tissue processor step. The second largest contributor (19%) was case accessioning, mostly attributable to production of single-use disposable jars. CONCLUSIONS: Applied to more than 20 million biopsies performed in the US annually, emissions from biopsy processing is equivalent to yearly GHG emissions from 1,200 passenger cars. Mitigation strategies may include modification of surveillance guidelines to include the number of specimen jars.

Interobserver Variation in Evaluating Perineural Invasion for Oral Squamous Cell Carcinoma: Phase 2 Survey Study.

In a previous study, we found interobserver agreement among 88 board-certified pathologists evaluating perineural invasion (PNI) in oral squamous cell carcinoma (OSCC) was fair, and participants most often used the following criteria: (1) tumor invading the perineurium, (2) tumor surrounding a nerve. In this study, we aimed to determine whether application of these most commonly used criteria may improve interobserver agreement. 512 pathologists were invited to participate in a web-based survey. Participants were asked to assess the presence/absence of PNI in a set of OSCC photomicrographs by applying each of the two criteria above. The survey was completed by 84 board-certified pathologists [mean age: 52 years (range 31-81), mean years in practice: 19 (range 1-56)]. Interobserver agreement was moderate (k = 0.46, 95% CI 0.45-0.46) when using definition #1 (tumor invading the perineurium) and fair (k = 0.24, 95% CI 0.23-0.25) when using definition #2 (tumor surrounding a nerve). By comparison, interobserver agreement was fair (k = 0.36, 95% CI 0.35-0.37) among phase 1 participants asked to evaluate these photomicrographs as they would in their pathology practice. Differences in kappa between definition #1 and phase 1, definition #2 and phase 2, and definition #1 and #2 were statistically significant (p < 0.001). Compared to our prior study based on pathologists' personal views, the current study shows improved interobserver agreement with application of the criterion, "tumor invading the perineurium." However, further work is needed to delineate concise, objective, and more reproducible criteria for histopathologic assessment of PNI.

Validation of Whole Slide Imaging for primary surgical pathology diagnosis of prostate biopsies.

CONTEXT: Whole slide imaging (WSI) is an important component of digital pathology which includes digitization of glass slides and their storage as digital images. Implementation of WSI for primary surgical pathology diagnosis is evolving, following various studies which have evaluated the feasibility of WSI technology for primary diagnosis. AIMS, SETTINGS AND DESIGN: The present study was a single-center, observational study which included evaluation by three pathologists and aimed at assessing concordance on specialty-specific diagnosis and comparison of time taken for diagnosis on WSI and conventional light microscopy (CLM). MATERIALS AND METHODS: Seventy prostate core biopsy slides (reported between January 2016 and December 2016) were scanned using Pannoramic MIDI II scanner, 3DHISTECH, Budapest, Hungary, at 20× and 40×. Sixty slides were used for validation study following training with 10 slides. STATISTICAL ANALYSIS USED: Intraobserver concordance for diagnosis between the two platforms of evaluation was analyzed using Cohen's κ statistics and intraclass correlation coefficient (ICC); observation time for diagnosis was compared by Wilcoxon signed-rank test. RESULTS: Interpretation on WSI using 20× and 40× was comparable with no major discordance. A high level of intraobserver agreement was observed between CLM and WSI for all three observers, both for primary diagnosis (κ = 0.9) and Grade group (κ = 0.7-0.8) in cases of prostatic adenocarcinoma. The major discordance rate between CLM and WSI was 3.3%-8.3%, which reflected the expertise of the observers. The time spent for diagnosis using WSI was variable for the three pathologists. CONCLUSION: WSI is comparable to CLM and can be safely incorporated for primary histological diagnosis of prostate core biopsies.

Audit in surgical histopathology at a tertiary healthcare center: Study of preanalytical and analytical phase.

CONTEXT: An audit aims to verify conformance to required processes, assess their implementation, and define the targets of quality control. AIMS: To evaluate preanalytic and analytic phases of surgical histopathology in a tertiary healthcare center. SETTING AND DESIGN: An observational retrospective and prospective study over 3 months each of year 2013 and 2014. MATERIALS AND METHODS: Biopsy, small resections, large organ resections, bone marrow aspirate/biopsy (BMA/BMB), and frozen section samples received in surgical histopathology were categorized as I to V, respectively. A manual audit was done for preanalytical phase (adequacy of clinical information and grossing adequacy) and analytical phase [turnaround time (TAT) and tissue section quality]. STATISTICAL ANALYSIS: Qualitative data was assessed by Chi-Square test. Quantitative data was assessed using One-Way Analysis of Variance. RESULTS: Among 3179 total cases, category I to V had 1558 (49%), 1099 (34.6%), 342 (10.8%), 124 (3.8%), and 56 (1.8%) cases, respectively. Category I had shortest TAT but maximum number of inadequately sent specimens and recuts. Category III had maximum cases with inadequate clinical history, grossing errors, additional sections, and longest TAT. Category IV had maximum cases with poor quality sections. Category V had maximum cases with inadequate demographic details and clinical investigations. BMB (114, 91.9%) was more useful than BMA for diagnosis. Mean TAT for fixed tissues and frozen tissues was 3.6 ± 1.8 days and 26.6 ± 11.2 min, respectively. CONCLUSIONS: Total 25% of annual workload was studied by an observational, manual audit. Quality indicators were achieved as per international norms despite limited resources. Remedial actions were suggested for technicians, clinicians, and pathologists to minimize errors.

Improvement of Pediatric Liver Core Biopsy Adequacy by Reducing Laboratory-Related Tissue Fragmentation and Increasing Portal Tract Yield.

OBJECTIVES: We aimed to identify potential laboratory causes of suboptimal liver biopsy quality and sought to implement corresponding measures to improve biopsy adequacy. METHODS: We prospectively measured the number and size of tissue fragments and the amount of portal tracts in 200 consecutive pediatric medical liver biopsies before and after quality improvement processes were initiated. RESULTS: We identified laboratory-related tissue fragmentation as a significant cause of low biopsy adequacy. The principal approaches to reduce fragmentation included establishment of multistep monitoring of tissue integrity, adjustment of specimen-processing conditions, and laboratory staff education and awareness. These adjustments collectively led to lower overall tissue fragmentation (decreasing from 59% to 24%, P < .01) and higher biopsy adequacy rates (increasing from 32% to 56%, P < .01). The number of evaluable portal tracts increased from 4.4 to 5.7 portal tracts per centimeter of core biopsy tissue (P < .01). CONCLUSIONS: We demonstrated a sustainable improvement in the overall quality of pediatric needle core liver biopsies by reducing tissue fragmentation. Effective laboratory adjustments included monitoring of tissue integrity, modifications of processing conditions, and laboratory staff education.

Assessment of a computerized quantitative quality control tool for whole slide images of kidney biopsies.

Inconsistencies in the preparation of histology slides and whole-slide images (WSIs) may lead to challenges with subsequent image analysis and machine learning approaches for interrogating the WSI. These variabilities are especially pronounced in multicenter cohorts, where batch effects (i.e. systematic technical artifacts unrelated to biological variability) may introduce biases to machine learning algorithms. To date, manual quality control (QC) has been the de facto standard for dataset curation, but remains highly subjective and is too laborious in light of the increasing scale of tissue slide digitization efforts. This study aimed to evaluate a computer-aided QC pipeline for facilitating a reproducible QC process of WSI datasets. An open source tool, HistoQC, was employed to identify image artifacts and compute quantitative metrics describing visual attributes of WSIs to the Nephrotic Syndrome Study Network (NEPTUNE) digital pathology repository. A comparison in inter-reader concordance between HistoQC aided and unaided curation was performed to quantify improvements in curation reproducibility. HistoQC metrics were additionally employed to quantify the presence of batch effects within NEPTUNE WSIs. Of the 1814 WSIs (458 H&E, 470 PAS, 438 silver, 448 trichrome) from n = 512 cases considered in this study, approximately 9% (163) were identified as unsuitable for subsequent computational analysis. The concordance in the identification of these WSIs among computational pathologists rose from moderate (Gwet's AC1 range 0.43 to 0.59 across stains) to excellent (Gwet's AC1 range 0.79 to 0.93 across stains) agreement when aided by HistoQC. Furthermore, statistically significant batch effects (p < 0.001) in the NEPTUNE WSI dataset were discovered. Taken together, our findings strongly suggest that quantitative QC is a necessary step in the curation of digital pathology cohorts. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Quality assurance in dermatopathology: A review of report amendments.

BACKGROUND: Systematic review of amended reports in surgical pathology has been recommended as a valuable exercise in promoting quality assurance and improvement. Examination of report amendments can identify defects in the surgical pathology process and inspire new approaches to decreasing error rates and improving overall patient care. METHODS: We performed a retrospective review of all amended dermatopathology reports over a 1.5-year period at a large academic institution. RESULTS: During the study period, 86 amended reports out of a total 7950 skin-specific reports were issued (1.08%). Of these amended reports, about 59% (51/86) were because of non-interpretative errors (eg, wrong site, chin vs shin, etc.) while 41% (35/86) were diagnostic misinterpretations. Of these 35, 24 were considered major diagnostic changes while six were minor. Five amendments provided additional diagnostic information. Of those amended reports with diagnostic misinterpretations, 14/35 involved melanocytic lesions, 8/35 involved non-melanoma skin cancers or keratinocyte atypia, 10/35 were inflammatory lesions and 3/35 involved other tumors. CONCLUSION: Our review points to several quality improvement areas that can be targeted to potentially avoid diagnostic errors in dermatopathology, including standardizing certain anatomic sites to prevent misidentification and seeking out clinicopathologic correlation in challenging melanocytic cases.

Grading variation in 2,934 patients with ductal carcinoma in situ of the breast: the effect of laboratory- and pathologist-specific feedback reports.

BACKGROUND: Histologic grade of ductal carcinoma in situ of the breast (DCIS) may become the single biomarker that decides whether patients will be treated. Yet, evidence shows that grading variation in daily practice is substantial. To facilitate quality improvement, feedback reports, in which laboratory-specific case-mix adjusted proportions per grade were benchmarked against other laboratories, were sent to the individual laboratories by March 1, 2018. One year later, the effect of these feedback reports on inter-laboratory variation was studied. METHODS: Synoptic pathology reports of all pure DCIS resection specimens between March 1, 2017 and March 1, 2019 were retrieved from PALGA (the nationwide Dutch pathology registry). Laboratory-specific proportions per grade were compared to the overall proportion in the year before and after feedback. The absolute deviation for all three grades at once, represented by the overall deviation score (ODS), was calculated as the sum of deviations from the grade-specific overall proportions. Case-mix adjusted, laboratory-specific odds ratios (ORs) for high- (grade III) versus low-grade (grade I-II) DCIS were obtained by multivariable logistic regression. RESULTS: Overall, 2954 DCIS reports from 31 laboratories were included. After feedback, the range between laboratories decreased by 22 and 6.5% for grades II and III, while an increase of 6.2% was observed for grade I. Both the mean ODS (27.2 to 24.1%) and maximum ODS (87.7 to 59.6%) decreased considerably. However, the range of case-mix adjusted ORs remained fairly stable and substantial (0.39 (95% CI: 0.18-0.86) to 3.69 (95% CI: 1.30-10.51)). CONCLUSION: A promising decrease in grading variation was observed after laboratory-specific feedback for DCIS grades II-III, while this was not observed for DCIS grade I. Overall, grading variation remained substantial which needs to be addressed considering its clinical implications. Nationwide consensus on a classification, and training of (expert breast) pathologists, for example by e-learning, may help to further improve grading standardization.

Variation in breast cancer grading: the effect of creating awareness through laboratory-specific and pathologist-specific feedback reports in 16 734 patients with breast cancer.

AIMS: Histological grade is widely used to guide the management of invasive breast cancer (IBC). Yet, substantial interlaboratory and intralaboratory grading variations exist in daily pathology practice. To create awareness and to facilitate quality improvement, feedback reports, containing case-mix-adjusted laboratory-specific grades benchmarked against other laboratories, were sent to the individual laboratories by 1 March 2018. We studied the effect of these feedback reports on interlaboratory grading variation up till 1 year later. METHODS: Overall, 17 102 synoptic pathology reports of IBC resection specimens from 33 laboratories, obtained between 1 March 2017 and 1 March 2019 were retrieved from the Dutch Pathology Registry (PALGA). An overall deviation score (ODS), representing the sum of deviations from the grade-specific overall proportions, was calculated to compare the absolute deviation for all grades at once. Case-mix correction was performed by two multivariable logistic regression analyses, providing laboratory-specific ORs for high-grade versus low-grade IBC. RESULTS: After feedback, the overall range between laboratories decreased by 3.8%, 6.4% and 6.6% for grades I, II and III, respectively. Though the mean ODS remained similar (13.8% vs 13.7%), the maximum ODS decreased from 34.1% to 29.4%. The range of laboratory-specific ORs decreased by 21.9% for grade III versus grades I-II. CONCLUSIONS: An encouraging decrease in grading variation of IBC was observed after laboratory-specific feedback. Nevertheless, the overall grading variation remains substantial. In view of the important role of grading in patient management, it is adamant that not only feedback should be provided on a regular basis but also other interventions, such as additional training, are required.

Lack of Standardization in the Processing and Reporting of Post-Neoadjuvant Breast Cancer Specimens.

CONTEXT.­: The use of neoadjuvant therapy in the management of early-stage invasive breast cancer is increasing. Residual Cancer Burden and other similar tools use pathologic characteristics of post-neoadjuvant therapy breast tumors to determine long-term outcome. However, there are no standardized guidelines for the pathologic evaluation of these specimens in the routine clinical setting. OBJECTIVE.­: To assess current practices among Canadian pathologists and pathology assistants with regard to the processing and reporting of post-neoadjuvant therapy breast specimens. DESIGN.­: An electronic survey was distributed to pathologists and pathology assistants across Canada. RESULTS.­: Sixty-three responses were obtained. A total of 48% (15 of 31) of surveyed pathologists reported familiarity with the Residual Cancer Burden tool. A total of 40% (25 of 63) of respondents reported a lack of routine use of specimen photography, and 35% (22 of 63) reported a lack of routine use of grossing diagrams. There was significant variation with respect to tumor bed sampling; the most common method was to submit 1 block per centimeter of tumor (20 of 63; 32%). There was also significant variation in the method of measuring residual tumor; the most common method was to measure the largest cross-section of residual tumor (16 of 32; 50%). CONCLUSIONS.­: There is a need for standardization of the evaluation of post-neoadjuvant therapy breast specimens in the routine clinical setting in Canada. We recommend the routine use of specimen mapping, submitting the largest cross section of tumor bed in toto, reporting tumor size as per American Joint Committee on Cancer and Residual Cancer Burden guidelines, and routinely including measurements of residual tumor cellularity and in situ disease in the final pathology report as per Residual Cancer Burden guidelines.

Practice Paradigms Before and After Introduction of the Diagnosis-Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP): an Institutional Experience.

The recently adopted terminology of "Noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP) reflects the indolent behavior of these tumors. In contrast to conventional papillary thyroid carcinomas, NIFTP can be managed conservatively. The purpose of this study was to investigate changes in surgical and pathologic practice patterns at our institution since the introduction of the NIFTP diagnosis in 2016. A retrospective analysis of all thyroid specimens received in our laboratory between January 2015 and April 2017 was performed. The final cohort consisted of 1508 thyroidectomy specimens from 1508 patients (1153 (76.5%) women and 355 (23.5%) men), of which 1011 (67%) were total thyroidectomies and 497 (33%) were partial thyroidectomies. There were 558 (69.2%) total thyroidectomies and 248 (30.8%) partial thyroidectomies performed prior to introduction of the NIFTP diagnosis and 453 (64.5%) and 249 (35.5%) total and partial thyroidectomies, respectively, after the change in nomenclature. Within a year following the initial use of this diagnosis, 67 NIFTP cases were identified (9.5% of all thyroidectomies), whereas compared with the year preceding it, malignant diagnoses decreased from 54.5 (439) to 44.6% (313), and the benign category remained unchanged from 44.5 (367) to 45.9% (322). For the entirely submitted 67 NIFTP cases, the mean number of blocks submitted was 14.7 (0.98 blocks/g); for malignant lesions 17.7 (0.92 blocks/g); and for benign lesions 16.6 (0.75 blocks/g). The results of our study suggest that NIFTP are encountered in almost 10% of thyroidectomies at our institution with expected shifts in cytology and surgical pathology diagnoses as a result of the change in nomenclature. During this time period, significant shifts towards less aggressive surgical management were not observed. All 67 NIFTP nodules were submitted entirely with no significant difference in the number of cassettes submitted for NIFTP nodules as compared with follicular variant papillary thyroid carcinoma (PTC), classic variant PTC, or follicular adenoma.

Challenges with colorectal cancer staging: results of an international study.

Challenges exist with standardized colorectal cancer reporting despite adoption of the American Joint Committee on Cancer-Staging Manual 8th edition. We performed this study to gauge current practice patterns among a diverse group of surgical pathologists. A web-based questionnaire depicting problematic issues and images related to colorectal carcinoma staging was circulated among 118 surgical pathologists and their responses were correlated with their geographic location (North America vs. Europe vs. others), nature of practice (academic vs. community), the sign-out model (gastrointestinal subspecialty vs. general surgical pathology), and years of professional experience. We found that a substantial number of practicing pathologists ignore recommended-staging criteria in specific settings, particularly with respect to assessment of advanced T stage. Tumors that communicated with the serosa through inflammatory foci were staged as pT3 (49%) or pT4a (51%) by nearly equal numbers of pathologists regardless of level of experience, the sign-out model, or geographic location. Only 65% assigned T stage and margin status based on extent of viable tumor in the neoadjuvant setting. One-third of pathologists, particularly those in Europe (p = 0.015), classified acellular mucin deposits as N1 disease when detected in treatment-naive cases. Nearly 50% of pathologists classified isolated tumor cells (i.e., deposits <0.2 mm) in lymph nodes as metastatic disease (i.e., pN1, p = 0.02). Our results suggest that pathologists ignore recommendations that are based on insufficient data and apply individualized criteria when faced with situations that are not addressed in the American Joint Committee on Cancer Staging Manual 8th edition. These variations in practice limit the ability to compare outcome data across different institutions and draw attention to areas that require further study.

Pathologic reporting practices for breast cancer specimens after neoadjuvant chemotherapy-a survey of pathologists in academic institutions across the United States.

Neoadjuvant chemotherapy is increasingly being used to treat primary invasive breast carcinoma. Response to neoadjuvant chemotherapy is an important determinant of prognosis. A multidisciplinary group published recommendations for standardization of pathologic reporting of postneoadjuvant chemotherapy specimens. Based on these recommendations, we sent a survey to 26 pathologists currently practicing breast pathology in academic centers across the United States. The survey consisted of six questions with yes/no answers. The pathologists were encouraged to add comments. We received responses from 23 breast pathologists from 19 centers. The questions and responses were as follows: 1. Do you grade tumors after neoadjuvant chemotherapy?-17 (74%) responded yes and 6 (26%) responded no. 2. Do you routinely repeat hormone receptors, HER2/Neu results after neoadjuvant chemotherapy?-15 (65%) responded yes and 8 (35%) responded no. 3. If there are features of tumor regression/tumor bed at the margin but no actual tumor at the margin do you report this?-11 (48%) responded yes and 8 (35%) responded no and 4 (17%) reported a variable practice. 4. Do you report number of nodes with fibrosis/changes of regression?-17 (74%) responded yes and 6 (26%) responded no. 5. Do you report residual cancer burden score on your report or at least provide information on your report so clinicians can calculate residual cancer burden?-17 (74%) responded yes and 6 (26%) responded no. 6. Do you have a specific synoptic for cases after neoadjuvant chemotherapy?-5 (22%) responded yes and 18 (78%) responded no. The major reasons provided for nonadherence to recommended guidelines included pathologists were unaware of prognostic importance of providing the information, reporting practices were clinician driven and some pathologists were unaware of the recommendation. We document that academic breast pathology practices show significant variability in reporting of postneoadjuvant chemotherapy cases. We document barriers to standard practice and provide recommendations we hope will contribute to a more uniform reporting practice for these complex specimens.

Digital pathology for intraoperative frozen section diagnosis of thoracic specimens: an evaluation of a system using remote sampling and whole slide imaging diagnosis.

BACKGROUND: Digital pathology is now used for primary diagnostic work as well as teaching, research and consultation. In our multisite institution service reorganisation led to histopathology being located in a separate hospital from some surgical specialities. We implemented remotely supervised specimen sampling and frozen section diagnosis using digital pathology. In this study we assessed the concordance of glass and digital slide diagnosis using this system. METHODS: We reviewed cases from the first 2 years of digital frozen section reporting at our institution. Cases with potential digital to glass slide discordance were reviewed by three experienced thoracic histopathologists. The reasons for discordance were determined and common themes identified. We also reviewed critical incidents relating to digital pathology during the study period. RESULTS: The study population comprised 211 cases. Frozen section to final diagnosis concordance between digital and glass slide diagnosis was found in 196 (92.6%) cases. The 15 potentially discordant cases were reviewed. Intraobserver concordance between glass and digital slide review ranged from 9/15 to 12/15 cases across the three pathologists. Glass slide review diagnosis showed better concordance with ground truth in two cases; digital slide review was more accurate in two cases. One relevant critical incident was identified during the study period. DISCUSSION: This is the largest study to examine digital pathology for thoracic frozen section diagnosis and shows that this is a safe and feasible alternative to glass slide diagnosis. Discordance between digital and glass slide diagnoses were unrelated to the processes of whole slide imaging and digital microscopy.

Lost in translation: confusion on resection and dissection planes hampers the interpretation of pathology reports for perihilar cholangiocarcinoma.

In perihilar cholangiocarcinoma (PHC), interpretation of the resection specimen is challenging for pathologists and clinicians alike. Thorough and correct reporting is necessary for reliable interpretation of residual disease status. The aim of this study is to assess completeness of PHC pathology reports in a single center and assess what hampers interpretation of pathology reports by clinicians. Pathology reports of patients resected for PHC at a single expert tertiary center drafted between 2000 and 2018 were assessed. Reports were assessed regarding completeness, according to the guideline of the International Collaboration on Cancer Reporting (ICCR). A total of 146 reports were assessed. Prognostic tumor characteristics such as vasoinvasive growth and perineural growth were missing in 30/146 (34%) and 22/146 (15%), respectively. One or more planes were missing in 94/146 (64%) of the reports, with the periductal dissection plane missing in 51/145 (35%). Residual disease could be re-classified from R0 to R1 in 22 patients (15%). Reasons for R1 in these patients were the presence of a positive periductal dissection plane (n = 2), < 1-mm margin at the periductal dissection plane (n = 11), or liver parenchyma (n = 9). Completeness of reports improved significantly when drafted by an expert HPB pathologist. This study demonstrates that pathology reporting of PHC is challenging. Reports are frequently incomplete and often do not incorporate assessment of all resection planes and the dissection plane. The periductal dissection plane is frequently overlooked, but is a major cause of residual disease.