CONTEXT.—: Clostridioides difficile infection (CDI) is the world-leading cause of infectious nosocomial diarrhea and pseudomembranous colitis. Antibiotics are the first line of treatment against CDI despite the high likelihood of antibiotic failure and/or recurrence. More data are needed to correlate clinical variables with 16S rRNA microbiome profiles in CDI-infected patients. OBJECTIVE.—: To determine the relationship(s) between a patient's clinical factors and the stool bacteriome of CDI-positive patients and CDI-negative patients with diarrheal symptoms. DESIGN.—: This study used stool samples and clinical data from 358 patients with nosocomial diarrhea, who were divided by their CDI diagnosis (CDI-negative: n = 180; CDI-positive; n = 178). The stool bacteriome was profiled by amplicon deep sequencing of the 16S rRNA gene, followed by correlating clinical data. RESULTS.—: The stool bacteriome was significantly different by severity assessment regardless of CDI status. Phyla and species varied significantly by CDI diagnosis. Severity, defined as a serum white blood cell count greater than 15 cells/μL and/or a creatinine level greater than 1.5 mg/dL, correlated significantly with dysbiosis of the stool bacteriome profile of CDI-positive patients compared to CDI-negative patients. Serum white blood cell count was significantly higher in patients with bacterial dysbiosis, and high levels of creatinine were associated with low bacteriome diversity. CONCLUSIONS.—: Clinical severity of CDI influences the stool microbiome of infected patients. To date, this study has the largest data set comparing 16S rRNA microbiome profiles and clinical variables between CDI-infected and noninfected individuals.

CONTEXT.—: Kikuchi-Fujimoto lymphadenitis, also known as Kikuchi-Fujimoto disease (KFD), is a self-limited lymphoproliferative disease, with no definitive causative agent confirmed by traditional methods. OBJECTIVES.—: To further explore the clinicopathologic features of KFD and clarify related pathogenic factors. DESIGN.—: A retrospective analysis was performed in a collection of KFD cases to review the clinical and histopathologic features, and metagenomics next-generation sequencing (mNGS) was used in 64 formalin-fixed, paraffin-embedded (FFPE) tissues from patients with KFD. RESULTS.—: One hundred five of the 170 patients with KFD (61.8%) were female; 10 patients had autoimmune diseases. Four pathologic subtypes were classified: necrotic (45.9%, 78 of 170), phagocytic (32.4%, 55 of 170), proliferative (17.1%, 29 of 170), and xanthomatous (4.7%, 8 of 170). Patients younger than 40 years with unilateral cervical lymphadenopathy and small vessel fibrinous degeneration accounted for significant differences among the 4 pathologic subtypes (P < .05). Among 64 patients with KFD, 9 had detectable bacterial or viral DNA-of 6 bacterial cases, 1 involved Chlamydia psittaci; while of 3 viral cases, 1 involved human beta herpesvirus 6B and 2 involved Epstein-Barr virus. No significant relationships were found between the pathologic subtypes and specific pathogens. CONCLUSIONS.—: Only a small proportion of patients with KFD had autoimmune diseases or infections from specific pathogens, suggesting that KFD is likely a reactive lesion of lymph nodes to various circumstances. To our knowledge, this is the first and the largest study to detect pathogens with the use of mNGS on FFPE samples in KFD. Our study also further confirms that mNGS can be used on FFPE samples to detect potentially infectious agents in clinical settings.

CONTEXT.—: The N-terminal prohormone of the brain natriuretic peptide (NT-proBNP) is a major diagnostic biomarker for heart failure. OBJECTIVE.—: To compare the analytical and clinical performance of 3 NT-proBNP immunoassays: the Atellica IM NT-proBNP assay (Siemens Healthcare Diagnostics), the Alere NT-proBNP assay (Abbott Laboratories), and the Elecsys proBNP II assay (Roche Diagnostics). DESIGN.—: For the Atellica IM NT-proBNP assay, analytical performance, including precision, linearity, and carryover, was fully evaluated. Method comparisons among the 3 assays were performed using the Passing-Bablok regression and κ agreement test. To evaluate the clinical performance of the assays, 160 patient samples were used from patients with (n = 81) or without (n = 79) heart failure. RESULTS.—: The analytical performance of the Atellica IM NT-proBNP assay was acceptable according to the manufacturer's claims. The Atellica IM NT-proBNP assay showed a positive bias compared with the Elecsys proBNP II assay. The Cohen κ values among the 3 assays were satisfactory (>0.80) and comparable. There were no significant differences in areas under the curve. However, for the diagnosis of heart failure, the Elecsys proBNP II showed a higher specificity and positive likelihood ratio than the other assays. CONCLUSIONS.—: All 3 NT-proBNP assays showed acceptable concordance, and their clinical performance was comparable. However, the Elecsys proBNP II might be a more discriminating NT-proBNP assay to diagnose heart failure.

CONTEXT.—: Epithelioid angiomyolipomas (eAMLs) are rare tumors of the kidney that occur in patients with tuberous sclerosis complex or in a sporadic setting; a subset of these tumors exhibit metastatic behavior. OBJECTIVE.—: To analyze molecular profiling data to identify pathogenic alterations in rare cases of metastatic eAML, and to identify immunohistochemistry (IHC)-based surrogate markers. DESIGN.—: Molecular profiling data from the American Association for Cancer Research GENIE registry was accessed for 23 patients with angiomyolipomas, and 9 of 16 patients with eAMLs in our institutional registry were evaluated with next-generation sequencing. IHC was performed to screen for alterations of P53, RB, and ATRX for all 16 institutional cases. RESULTS.—: Combined alterations of 5 tumor-suppressor genes (TP53, ATRX, RB1, APC, and NF1) were identified using next-generation sequencing in 7 of 8 (88%) patients with metastatic disease compared to a single patient with nonmetastatic disease (RB1 variant of uncertain significance; 1 of 24, 4%). No cases with abnormal IHC results were identified in 11 patients with nonmetastatic disease compared to 3 of 5 patients with metastatic disease. CONCLUSIONS.—: Our results show that the majority of metastatic eAMLs have mutations of 5 tumor-suppressor genes (TP53, ATRX, RB1, APC, and NF1), while these are rare in patients with nonmetastatic disease. Furthermore, IHC for P53, RB, and ATRX may serve as a screen for a subset of these alterations in resource-limited settings. These findings, if validated in larger data sets, have the potential to predict metastatic behavior in eAML.

CONTEXT.—: Despite widely prevalent burnout and attendant disengagement in medicine, the specific patterns and drivers within pathology and laboratory medicine are uncommonly studied. OBJECTIVE.—: To assess the prevalence and drivers of burnout among pathology and laboratory medicine professionals, retrospectively, prior to the COVID-19 pandemic. DESIGN.—: This was a cross-sectional, mixed-methods study engaging pathology and laboratory medicine professionals as subjects. RESULTS.—: Of 2363 respondents, 438 identified as pathologists, 111 as pathology assistants, and 911 as pathology and laboratory professionals. The burnout rate was 58.4% (1380 of 2363) across all respondents in pathology and laboratory medicine. Burnout varied by job role (P < .01) and was highest among pathology and laboratory professionals. Disparities in burnout rate were observed by race. Fifty-six percent (1323 of 2363) of respondents felt that they had at least 1 symptom of burnout and were advancing toward a breaking point. Underlying factors ranked highly among all groups included control over workload and loss of meaning in work. CONCLUSIONS.—: Data provided from this cohort may help departments create successful strategies to reduce disengagement and burnout in the laboratory, especially during periods of increased stress as experienced during the COVID-19 pandemic. Further, these data may serve as a baseline comparison for future studies.

CONTEXT.—: Although several neuroendocrine cell types constitute gastroenteropancreatic neuroendocrine tumors (NETs), the clinical and prognostic implications of the expression of multiple peptide hormones have not been comprehensively evaluated in rectal NETs. OBJECTIVE.—: To identify the clinicopathologic characteristics and prognostic impact of peptide hormone expression. DESIGN.—: We evaluated the expression of peptide YY (PYY), glucagon, somatostatin, serotonin, insulin, and gastrin using immunolabeling in 446 endoscopically or surgically resected rectal NETs. RESULTS.—: PYY, glucagon, serotonin, somatostatin, insulin, and gastrin were expressed in 261 of 389 (67.1%), 205 of 446 (46.0%), 36 of 446 (8.1%), 33 of 446 (7.4%), 2 of 446 (0.4%), and 1 of 446 cases (0.2%), respectively. Immunoreactivity to any peptide hormone was present in 345 of 446 cases (77.4%). Tumors expressing serotonin or somatostatin were associated with lymphovascular invasion, chromogranin A expression, and shorter disease-free survival (DFS). Rectal NETs were classified as L-cell, enterochromaffin-cell, D-cell, null-expression, or mixed-expression type based on peptide hormonal expression status. Patients with D-cell NET had the shortest DFS (10-year DFS, 54.5%), followed by those with enterochromaffin-cell NET (89.5%), null expression (97.0%), L-cell NET (99.6%), and mixed-expression NET (100%; P < .001). Multivariable analyses revealed that somatostatin expression was an independent indicator of poor prognosis with respect to DFS in rectal NETs (P = .001). CONCLUSIONS.—: Somatostatin expression is a poor prognostic indicator in patients with rectal NETs. Therefore, additional peptide hormonal immunolabeling, including somatostatin, serotonin, and PYY, in rectal NETs can provide more information regarding DFS.

CONTEXT.—: The follow-up of patients under lifelong immunosuppressant therapy is pivotal to prevent allograft rejection after transplant. Part of the difficulties associated with routine monitoring of immunosuppressant concentrations can be alleviated by home sampling using dried blood spots (DBSs). OBJECTIVE.—: To evaluate the applicability of a DBS method for the determination of immunosuppressants in venous blood samples, making use of an automated extraction platform. DESIGN.—: Paired venous DBSs and whole blood samples were analyzed for tacrolimus (n = 162), sirolimus (n = 47), everolimus (n = 45), and cyclosporin A (n = 61) with liquid chromatography coupled to tandem mass spectrometry, using fully automated extraction for DBSs. Agreement between the automated DBS and whole blood method was assessed by using Bland-Altman comparison. Both an analytical and a clinical acceptance limit were predefined at more than 67% of all paired samples within 20% of the mean of both samples and more than 80% of all paired samples within 20% of the whole blood concentration, respectively. RESULTS.—: An impact of the hematocrit (hct) on DBS quantitation was observed for all analytes, which could be alleviated for all analytes by using a hct conversion formula based on a tacrolimus data subset: [DBScorrected] = [DBSmeasured]/(1.6305 - 1.559*hct). After correction, both analytical and clinical acceptance criteria were met for all analytes. CONCLUSIONS.—: Automated DBS analysis shows great potential for routine therapeutic drug monitoring of immunosuppressants, avoiding any manual sample handling.

CONTEXT.—: Pseudocarcinomatous urothelial hyperplasia (PCUH) architecturally and cytologically mimics cancer. The urine cytology features of PCUH have not been described. OBJECTIVE.—: To describe PCUH features in urine cytology. DESIGN.—: We reviewed urine cytology cases with concurrent PCUH tissue specimens from 5 academic institutions and classified them by using The Paris System criteria. RESULTS.—: Thirty-nine patients included 31 men and 8 women with a mean age of 67 years (range, 39-87 years). All patients had prior pelvic irradiation, and most presented with hematuria (n = 27). The specimens included voided urine (n = 16); bladder washing (n = 11); and urine, not otherwise specified (n = 12). The specimen preparation included cytospin (n = 29) and ThinPrep (n = 10). Original interpretations were negative for high-grade urothelial carcinoma (n = 28), atypical urothelial cells (AUCs; n = 10), and high-grade urothelial carcinoma (HGUC; n = 1). Twenty-five urine specimens (64%) had findings of PCUH. These specimens were moderately cellular and composed of sheets, cohesive groups, or isolated urothelial cells. Nucleoli were present in 23 cases. The nuclear membrane was smooth to irregular (n = 9), smooth (n = 8), and irregular (n = 8). The chromatin was glassy (n = 8), vesicular (n = 7), hyperchromatic (n = 7), and vesicular to finely granular (n = 3). The cytoplasm varied from dense squamoid, to finely vacuolated, to vacuolated. Nucleomegaly was observed in all 25 specimens, and nuclear-cytoplasmic ratio greater than 0.5 was seen in 11 of 25 cases (44%). The background contained acute inflammation (n = 14), was clean (n = 9), and contained red blood cells (n = 2). All cases originally interpreted as AUCs and HGUC had PCUH features. CONCLUSIONS.—: PCUH urine features can overlap with AUCs, HGUC, and other nonurothelial malignancies. In our cohort, 44% (11 of 25) of urine specimens with PCUH changes were initially misclassified. Recognition of cytologic features of PCUH is important to avoid overcalling reactive changes.

CONTEXT.—: With the adoption of Epic/Beaker at our institution, surgical pathology specimens are assigned a Current Procedural Terminology (CPT) charge code at the time of accessioning, and pathologists have been made responsible for verifying the accuracy of the code before signing out the case. OBJECTIVE.—: To determine with what frequency attending pathologists reassigned the correct charge code to a specimen when the code assigned at accessioning was incorrect, as well as to estimate the potential financial impact of missed changes. DESIGN.—: We reviewed all specimens received for frozen section during a 7-month period, identified specimens where the default charge code that our departmental protocol assigns at frozen section (88305) was incorrect, and assessed the rate of successful code change by pathologists and the potential financial cost of each missed change. RESULTS.—: Three hundred fifty-two of 2191 frozen section specimens (16%) required a change in the 88305 charge code. The codes for 195 specimens (55%) were correctly changed by the attending pathologist, while 157 (45%) were not changed (149) or changed to an incorrect charge code (8). Individual pathologist change rates ranged from 0% to 100%, with a mean and median change rate of 43% and 24%, respectively. Using average code reimbursements at our institution, the loss in revenue from the 157 missed and incorrect frozen section changes was estimated at $13 788 ($1970 per month). CONCLUSIONS.—: Pathologists showed highly variable rates of correcting CPT charge codes when the incorrect code had been previously assigned to a case, with associated loss of revenue from missed and incorrect code changes.

CONTEXT.—: Pathologists often provide extensive consultative services to other physicians beyond establishing a diagnosis or providing laboratory test results, but they are typically not financially compensated for these services. Another relatively new role for pathologists in the United States is as a consultant who works directly with patients. OBJECTIVE.—: To review how pathologists provide detailed consultation to other physicians, how pathologists can be financially compensated for this critical service, and how pathologists are increasingly serving as a consultant directly with patients and their families. DATA SOURCES.—: Sources were peer-reviewed medical literature and the author's personal experience. CONCLUSIONS.—: In recognition of the extensive consultative services provided by both clinical and anatomic pathologists to other physicians, procedural codes recently approved and valued by the Centers for Medicare & Medicaid Services now provide a compensation mechanism for these services for government-insured and potentially privately insured patients. Pathologists are also increasingly providing consultative services directly to patients, resulting in significant patient satisfaction and providing important support for patients and their physicians.

CONTEXT.—: Unnecessary laboratory tests are ordered because of factors such as preselected orders on order sets, clinician habits, and trainee concerns. Excessive use of lab testing increases patient discomfort via unnecessary phlebotomy, contributes to iatrogenic anemia, increases risk of bloodstream infections, and increases the cost of care. OBJECTIVE.—: To address these concerns, we implemented a multilevel laboratory stewardship intervention to decrease unnecessary laboratory testing, measured by laboratory tests per day attributed to service, across 2 surgical divisions with high lab use. DESIGN.—: The multilevel intervention included 5 components: stakeholder engagement, provider education, computerized provider order entry modification, performance feedback, and culture change supported by leadership. The primary outcome of the study was laboratory tests ordered per patient-day. Secondary outcomes included the number of blood draws per patient-day, total lab-associated costs, length of stay, discharge to a nursing facility, 30-day readmissions, and deaths. A difference-in-differences analytic approach assessed the outcome measures in the intervention period, with other surgical services as controls. RESULTS.—: The primary outcome of laboratory tests per patient-day showed a significant decrease across both thoracic and cardiac surgery services, with between 1.5 and 2 fewer tests ordered per patient-day for both services and an estimated 20 000 fewer tests performed during the intervention period. Blood draws per patient-day were also significantly decreased on the thoracic surgery service but not for cardiac surgery. CONCLUSIONS.—: A multilevel laboratory stewardship intervention targeted to 2 surgical services resulted in a significant decrease in laboratory test use without negatively impacting length of stay, readmissions, or mortality.

CONTEXT.—: Machine learning (ML) allows for the analysis of massive quantities of high-dimensional clinical laboratory data, thereby revealing complex patterns and trends. Thus, ML can potentially improve the efficiency of clinical data interpretation and the practice of laboratory medicine. However, the risks of generating biased or unrepresentative models, which can lead to misleading clinical conclusions or overestimation of the model performance, should be recognized. OBJECTIVES.—: To discuss the major components for creating ML models, including data collection, data preprocessing, model development, and model evaluation. We also highlight many of the challenges and pitfalls in developing ML models, which could result in misleading clinical impressions or inaccurate model performance, and provide suggestions and guidance on how to circumvent these challenges. DATA SOURCES.—: The references for this review were identified through searches of the PubMed database, the US Food and Drug Administration white papers and guidelines, conference abstracts, and online preprints. CONCLUSIONS.—: With the growing interest in developing and implementing ML models in clinical practice, laboratorians and clinicians need to be educated in order to collect sufficiently large and high-quality data, properly report the data set characteristics, and combine data from multiple institutions with proper normalization. They will also need to assess the reasons for missing values, determine the inclusion or exclusion of outliers, and evaluate the completeness of a data set. In addition, they require the necessary knowledge to select a suitable ML model for a specific clinical question and accurately evaluate the performance of the ML model, based on objective criteria. Domain-specific knowledge is critical in the entire workflow of developing ML models.

CONTEXT.—: Pathologists' Assistants (PathAs) have been involved in the traditional roles of macroscopic examination ("grossing"), frozen sections, and autopsy since the profession was developed in the 1970s as a response to the perceived workforce shortage in pathology. Additionally, PathAs are well suited for nontraditional roles in the laboratory, but are often underused in these roles because a PathA's value is easier to see in traditional roles. OBJECTIVE.—: To describe the nontraditional roles PathAs are involved in and how PathAs in these roles bring value to pathologists, patients, and health care organizations. DATA SOURCES.—: Literature about PathAs was reviewed and interviews with pathologists and PathAs in nontraditional roles were conducted. CONCLUSIONS.—: PathAs are capable of handling a wide range of nontraditional roles in the pathology laboratory. Using PathAs to the full extent of their knowledge, skills, and interests will bring value to pathology practices, PathAs, organizations, and patients through increased quality of care, saved pathologist time, higher revenues, and improved department reputation. Using PathAs in these roles also has the potential to evolve pathology practices and the PathA profession.

CONTEXT.—: Consequences related to nicotine (NIC) use remain a major health concern, leading to demand for testing to detect NIC, metabolites such as cotinine (COT), and related tobacco alkaloids, including anabasine (ANAB). NIC-related testing is not standardized among laboratories, nor are there clinical or regulatory guidelines to inform decisions such as appropriate screening cutoffs or limits of quantitation. OBJECTIVE.—: To evaluate analytical performance and reporting practices of laboratories that perform NIC-related testing by reviewing participant responses to the Nicotine and Tobacco Alkaloid (NTA) Proficiency Testing Survey. DESIGN.—: NTA results were retrieved from 2017 (the first year of the survey) through 2020. Survey participants, methodologies, and results were evaluated for all analytes, and simulated grading was performed for COT. Additional data, including limits of quantitation, qualitative cutoffs, and reasons for testing, were reviewed. RESULTS.—: Participant growth was steady for qualitative COT testing. Participation was stable for NIC, ANAB, and quantitative COT testing. Overall, participants performed well on survey challenges. However, reporting thresholds were widely divergent, ranging from 10 to 3000 ng/mL and 0.5 to 300 ng/mL, respectively, for qualitative and quantitative COT testing. Screening cutoffs were as high as 100 ng/mL for ANAB and 1000 ng/mL for NIC. CONCLUSIONS.—: Although participating laboratories performed well on the NTA Survey, the wide diversity of qualitative and quantitative reporting thresholds creates substantial risk for misinterpretation of results, and could lead to analytical concerns such as excessively high false-negative or false-positive rates. NIC-related testing would benefit from evidence-based guidelines to drive standardization of reporting.

CONTEXT.—: Immune thrombotic thrombocytopenic purpura (iTTP) is a rare but potentially fatal blood disorder resulting from acquired deficiency of plasma ADAMTS13, a metalloprotease that cleaves endothelium-derived ultralarge von Willebrand factor. Standard of care for iTTP including therapeutic plasma exchange, caplacizumab, and immunosuppressives, known as triple therapy, has led to a significant reduction in the disease-related mortality rate. The first International Society of Thrombosis and Haemostasis TTP guidelines stress the importance of having plasma ADAMTS13 activity testing in the algorithm for diagnosis and management of iTTP. However, the predictive role of assessing plasma ADAMTS13 activity and inhibitors or other ADAMTS13-related parameters in patients with acute iTTP and during remission has not been systematically evaluated. OBJECTIVE.—: To review and assess the predictive values of testing plasma ADAMTS13 activity, antigen, and inhibitors or anti-ADAMTS13 immunoglobulin G at various stages of disease in outcomes of iTTP. DATA SOURCES.—: Peer-reviewed publications and personal experience. CONCLUSIONS.—: We conclude that assessing ADAMTS13 biomarkers is not only essential for establishing the initial diagnosis, but also crucial for risk stratification and the early detection of disease recurrence. This may guide therapeutic interventions during acute episodes and for long-term follow-up of iTTP patients.

Comment in Arch Pathol Lab Med. 2022 Oct 1;146(10):1180-1181.

Comment in Arch Pathol Lab Med. 2022 Oct 1;146(10):1182a-1182.

CONTEXT.—: The US Food and Drug Administration (FDA) approved immune checkpoint inhibitor therapy for patients with advanced solid tumors that have DNA mismatch repair defects or high levels of microsatellite instability; however, the FDA provided no guidance on which specific clinical assays should be used to determine mismatch repair status. OBJECTIVE.—: To develop an evidence-based guideline to identify the optimal clinical laboratory test to identify defects in DNA mismatch repair in patients with solid tumor malignancies who are being considered for immune checkpoint inhibitor therapy. DESIGN.—: The College of American Pathologists convened an expert panel to perform a systematic review of the literature and develop recommendations. Using the National Academy of Medicine-endorsed Grading of Recommendations Assessment, Development and Evaluation approach, the recommendations were derived from available evidence, strength of that evidence, open comment feedback, and expert panel consensus. Mismatch repair immunohistochemistry, microsatellite instability derived from both polymerase chain reaction and next-generation sequencing, and tumor mutation burden derived from large panel next-generation sequencing were within scope. RESULTS.—: Six recommendations and 3 good practice statements were developed. More evidence and evidence of higher quality were identified for colorectal cancer and other cancers of the gastrointestinal (GI) tract than for cancers arising outside the GI tract. CONCLUSIONS.—: An optimal assay depends on cancer type. For most cancer types outside of the GI tract and the endometrium, there was insufficient published evidence to recommend a specific clinical assay. Absent published evidence, immunohistochemistry is an acceptable approach readily available in most clinical laboratories.